Trail Smelter Arbitration (United States v. Canada)

Sulphur dioxide fumes from a Canadian smelter at Trail, British Columbia, damaged crops and trees across the border in Washington State. The United States and Canada sent the dispute to a three-member Tribunal under a Convention signed at Ottawa on 15 April 1935. The Tribunal gave two decisions, on 16 April 1938 and 11 March 1941, and its 1941 reasoning on a State's duty not to let its territory be used to injure another is the best-known part of the award.

Quick Revision

Read the full judgment: legal.un.org (unofficial copy)

Parties

The award has no numbered paragraphs. Each point cites the decision (1938 or 1941) and its Part or heading. 1938 means the decision reported on 16 April 1938. 1941 means the decision reported on 11 March 1941.

• United States of America — claimant State. It complained that fumes from the Trail Smelter damaged the State of Washington (Convention, preamble; 1938, introduction).
• Dominion of Canada — respondent State. The smelter stands in its territory. By the Convention it assumed international responsibility for the damage (1938, introduction; Convention, Article XII).
• Consolidated Mining and Smelting Company of Canada, Limited — the private company that runs the Trail Smelter. The Tribunal read the words Trail Smelter to mean this company, its successors and assigns (1938, Part Two; 1938, Part Four, clause 11).
• Charles Warren — member chosen by the United States. He is described as of Massachusetts (1938, introduction).
• Robert A. E. Greenshields — member chosen by Canada. He is described as of the Province of Quebec (1938, introduction).
• Jan Frans Hostie — Chairman, chosen jointly by the two Governments. He is described as of Belgium (1938, introduction).
• Reginald S. Dean — scientist designated by the United States. He is described as of Missouri. He later served as a Technical Consultant (1938, introduction; 1938, Part Four).
• Robert E. Swain — scientist designated by Canada. He is described as of California. He later served as a Technical Consultant (1938, introduction; 1938, Part Four).
• Victor H. Gottschalk — designated by the United States in November 1940 as alternate to Reginald S. Dean (1941, introduction).
• Mr. Sherley — Agent for the United States. Mr. Tilley — counsel for Canada. Mr. Raftis — counsel for the United States in December 1940 (1938, Part Two, clause 7; 1941, Part Four, Section 4).
• Individual landowners and farmers of Washington — not parties. The Tribunal said it did not sit to decide claims of individuals. Their damage only served as a scale for working out reparation due to the State (1938, introduction; 1941, introduction).

Procedural History

1. In June 1927 the Consul General of the United States at Ottawa first raised the fumes problem officially with the Canadian Government (1938, Part One).
2. In December 1927 the United States proposed that the problems of the Trail Smelter go to the International Joint Commission (1938, Part One).
3. On 7 August 1928 the two Governments referred the matter to that Commission under Article IX of the Convention of 11 January 1909. Article IX says such reports are not decisions on the facts or the law and are not arbitral awards (1938, Part One; 1941, Part One, II).
4. The Commission asked five questions. The first two were the extent of damage to property in Washington, and the indemnity for past damage (1938, Part One).
5. The Commission sat at Northport in October 1928, in Washington D.C. in April 1929, at Nelson, B.C. in November 1929, and in Washington D.C. on 22 January and 12 February 1930 (1938, Part One).
6. On 28 February 1931 the Commission gave a unanimous report. It fixed $350,000 as the sum for all damage up to and including 1 January 1932. That sum did not cover damage after 1 January 1932 (1938, Part One; 1941, Part One, II).
7. The report recommended that claims for damage after 1 January 1932, not adjusted by the company within a reasonable time, be fixed by the two Governments and paid by the company. No such claims were made (1938, Part One).
8. The report also recommended that the company build sulphuric acid units. It further recommended whatever action was needed to reduce the fumes drifting into the United States until they did no damage there (1938, Part One; 1941, Part One, II).
9. The report failed to win the acceptance of both Governments. Canada has paid the United States $350,000 (1941, Part One, II).
10. On 17 February 1933 the United States told Canada that conditions were unsatisfactory and damage was still occurring. Diplomatic talks followed (1938, Part One; 1941, Part One, II).
11. On 15 April 1935 the two Governments signed the Convention for Settlement of Difficulties Arising from Operation of Smelter at Trail, B.C., at Ottawa. Ratifications were exchanged on 3 August 1935 (Convention; 1938, introduction).
12. Article I of the Convention bound Canada to pay $350,000 within three months of the exchange of ratifications. This was in payment of all damage in the United States before 1 January 1932 (Convention, Article I).
13. Article II set up the Tribunal: a Chairman and two national members. The Chairman must be a jurist of repute who is neither a British subject nor a United States citizen. The Governments choose him, or, failing agreement within nine months, the President of the Permanent Administrative Council of the Permanent Court of Arbitration at The Hague chooses him. That Council is the one described in Article 49 of the Hague Convention for the Pacific Settlement of International Disputes of 18 October 1907. Each Government names one member, a jurist of repute not associated with the controversy. Each may name a scientist to assist (Convention, Article II).
14. Article III told the Tribunal to finally decide four Questions. They are set out under Issues Raised (Convention, Article III; 1938, introduction).
15. Article IV said the Tribunal shall apply the law and practice followed in dealing with cognate (related) questions in the United States of America as well as international law and practice. It must also give consideration to the desire of the high contracting parties to reach a solution just to all parties concerned (Convention, Article IV).
16. Article V set the written procedure. Within nine months each Agent presents a statement of facts and evidence. Within six months after that, each presents an answer with further evidence and argument (Convention, Article V).
17. Article VI required each Government to send the full record to every Tribunal member. Article VII let the Tribunal then meet and decide on further procedure, considering the Agents' requests (Convention, Articles VI and VII).
18. Article VIII let the Tribunal hear representations, take oral or documentary evidence from the Governments or interested parties, administer oaths and make investigations (Convention, Article VIII).
19. Article IX made the Chairman preside and rule on evidence and procedure. Each member has one vote. The majority prevails and a dissent is recorded. If no two members agree, the Chairman decides (Convention, Article IX).
20. Article X required the Tribunal, on Question 1 and on indemnity for 1932 and 1933, to give due regard to later investigations. It let investigators enter and view properties where damage is claimed (Convention, Article X).
21. Article XI required the Tribunal to report its final decisions and reasons within three months after the proceedings conclude. The time can be extended by agreement. After the report the Governments may arrange the disposal of claims for later damage (Convention, Article XI).
22. Article XII bound the Governments to take the action needed for due performance and compliance with the Tribunal's decision. Article XIII made each Government pay its own costs and its member's and scientist's costs. Shared costs, including the neutral member's honorarium, are borne in equal shares. Article XIV made the Convention effective on the exchange of ratifications (Convention, Articles XII to XIV).
23. The Tribunal met in Washington D.C. on 21 and 22 June 1937 to organise, adopt rules of procedure and hear preliminary statements. Article 16 of those rules, adopted on 22 June 1937 with both Agents agreeing, said that where the rules are silent the Tribunal shall proceed as international law, justice and equity may require (1938, introduction; 1941, Part Two, I).
24. From 1 to 6 July 1937 the Tribunal travelled over the affected area in the north of Stevens County, Washington. It also inspected the Trail Smelter plant (1938, introduction).
25. It heard evidence at Spokane from 7 to 29 July 1937, in Washington D.C. on 16 to 19 August 1937, and in Ottawa from 23 August to 18 September 1937. It heard counsel in Ottawa from 12 to 19 October 1937 (1938, introduction).
26. On 2 January 1938 the Agents jointly told the Tribunal they had nothing more to present. Article XI then required a report within three months, that is by 2 April 1938 (1938, introduction).
27. The Tribunal told the Agents that a permanent decision by 2 April 1938 would rest on data it thought inadequate and unsatisfactory. On its recommendation the Governments extended the time to three months from 1 October 1940. They agreed by letters of 14 March 1938 and 22 March 1938 (1938, introduction; 1941, Part Two, I).
28. On 16 April 1938 the Tribunal reported its first decision. It gave its final decision on Question 1 and a temporary decision on Questions 2 and 3. It set up a temporary régime (a set of operating controls) and left the final decision on Questions 2, 3 and 4 for later (1938, introduction; 1941, introduction).
29. The 1938 decision appointed two Technical Consultants, Reginald S. Dean and Robert E. Swain. They stopped acting as Advisers to the Tribunal during the trial period (1938, Part Four, clause 1).
30. Dr. J. Patterson was appointed consulting meteorologist on 4 May 1938. He resigned on 1 May 1939 to join the Canadian Air Force. Dr. E. W. Hewson replaced him (1941, Part Four, Section 1).
31. On 4 May 1938 the Tribunal authorised Dr. John P. Nielsen, an American citizen, as assistant to the Technical Consultants. He served until 1 October 1938 (1941, Part Four, Section 1).
32. The Technical Consultants ran the trial period from May 1938 to 1 October 1940. They filed a Final Report, Meteorological Investigations near Trail, B.C., 1938-1940, of 374 pages (1941, Part Four, Section 1).
33. The Tribunal met the Technical Consultants at Washington D.C. from 24 April to 1 May 1939, as clause 7 of Part Four of the 1938 decision required. They reviewed reports and settled the course for the rest of the trial period (1941, introduction).
34. The trial period was not ended before 1 October 1940. The Tribunal wanted supplementary statements and a fresh hearing. A hearing was set for 1 October 1940. The United States' supplementary statement reached Canada only on 25 September 1940 because of disrupted postal links, so the public meeting was postponed (1941, introduction).
35. The Tribunal met at Boston on 26 and 27 September 1940 to adopt additional rules of procedure (1941, introduction).
36. In November 1940 the United States named Victor H. Gottschalk as alternate to Reginald S. Dean (1941, introduction).
37. The Tribunal met its scientific advisers at Montreal from 5 to 8 December 1940 to consider their Final Report. It then held a public meeting and heard counsel at Montreal from 9 to 12 December 1940 (1941, introduction).
38. The two Governments extended the time for the final decisions to 12 March 1941 (1941, introduction).
39. On 11 March 1941 the Tribunal reported its final decisions, signed by Jan Hostie, Charles Warren and R. A. E. Greenshields (1941, introduction and end).
40. On 6 May 1941 the three members sent both Governments a letter transmitting a letter from the Technical Consultants dated 28 April 1941. The members declared that its statement correctly interprets clause IV, Section 3 of Part Four of the 1941 decision (1941, Annex I).
41. The Consultants' letter says a strict reading of that clause could force a complete shutdown. It asks that the words untreated sulphur dioxide from the roasting plants be read into the clause. Tail gases and small escapes from blast furnaces and other operations were never meant to be covered (1941, Annex II).

Facts

Facts are in date order. The locality and the earlier smelter come first because the award describes them first.

1. The Columbia River rises in Canada. At Trail, British Columbia, it flows past a smelter in a gorge where zinc and lead are smelted in large quantities (1938, Part One; 1941, Part One, I).
2. From Trail the river runs east and then curves to the international boundary, about seven miles away in a straight line and about eleven miles by the river. South of the boundary it keeps a south-westerly course (1938, Part One).
3. Mountains rise 3,000 to 4,500 feet above sea level on both sides. The valley is one to two miles wide, with bench lands at various heights (1938, Part One).
4. Columbia Gardens lies about halfway between Trail and the boundary. Boundary is on the American side at the boundary. The Stroh farm is four or five miles south of the boundary (1938, Part One).
5. Columbia Gardens, Boundary and the Stroh farm each held automatic sulphur dioxide recorders installed by one Government or the other. Northport, a town on the east bank about nineteen miles from Trail by river and thirteen in a straight line, also had recorders (1938, Part One).
6. South of Northport lie Marble, Bossburg, Evans, Marcus and Kettle Falls. Kettle Falls is about forty-one miles from the boundary and is the southern limit of the area for which evidence was given. All these towns are small (1938, Part One).
7. The 1941 decision adds two details. Waneta (Canadian side) and Boundary (American side) lie at the boundary near the Pend-d'Oreille. Fowler Farm lies on the west bank four or five miles south of the boundary (1941, Part One, I).
8. The climate is dry but not arid. Average annual rainfall at Northport from 1923 to 1936 was slightly under seventeen inches. It ranged from 9.60 inches in 1929 to 26.04 inches in 1927. The 1941 decision gives the 1923 to 1940 average as somewhat above seventeen inches (1938, Part One; 1941, Part One, I).
9. The surface wind usually blows from the north-east down the river valley, but it varies by time of day and season (1938, Part One).
10. Few settlers lived in the area before 1892. The Spokane and Northern Railway reached Northport in 1892, and the town was founded that year. Northport's population was 787 in 1900, 476 in 1910, 906 in 1920 and 391 in 1930 (1938, Part One).
11. Farm land in the precincts nearest the boundary (Boundary and Northport) was 5,292 acres in 1925, 8,040 in 1930 and 5,666 in 1935. Crop land there was 798 acres in 1925, 1,227 in 1930 and 963 in 1935. The 1941 decision adds 7,175 acres of farm land and about 900 acres of crop land in 1940 (1938, Part One; 1941, Part One, I).
12. About 1896 the Breen Copper Smelter was set up at Northport. Later the Northport Smelting and Refining Company, chartered in 1901, ran it. It used heap roasting and released about seventy tons of sulphur a day (1938, Part One).
13. That smelter worked intermittently to 1908, lay idle from 1908 to 1915, resumed in March 1916 for lead ore and ceased on 5 March 1921. About 30 tons of sulphur a day were then emitted. The Tribunal said damage was undoubtedly caused over a restricted area (1938, Part One).
14. Before 1908 the Northport company bought smoke easements from sixteen landowners over 2,330 acres. From 1916 to 1921 it bought more from thirty-four owners over 5,556.7 acres. Courts in Stevens County heard several claims (1938, Part One).
15. Lumber was once the main industry, but the timber has largely gone. In 1929 fifteen of eighteen sawmills within a radius covering about 35,000 acres around Northport had been abandoned. The causes were in dispute (1938, Part One).
16. Farming is on the valley, benches, slopes and tributary valleys. The soils are light and sandy. About one-third of the land in the Upper Columbia Basin is unfit for farming, according to a 1913 United States Department of Agriculture report the Tribunal cited (1938, Part One).
17. Dr. F. C. Wyatt, head of the Soils Department of the University of Alberta, reported in 1929 that the crop range of these soils is wide and embraces the crops suited to the climate. Under good cultural operations yields are good. Soil in the tributary valleys is more loamy and fertile. On some slopes natural sub-irrigation gives enough moisture, but elsewhere irrigation is desirable (1938, Part One; 1941, Part One, I).
18. A large portion of the area is not primarily suited to agriculture. The 1913 Department of Agriculture report said about one-third of the Upper Columbia Basin is unsuited for farming, being too stony, too rough, too steep or a combination of these. To utilize that land and meet the wood needs of a growing population, the Basin must consider reforestation and conservation (1938, Part One; 1941, Part One, I).
19. Most farms are 80 to 160 acres. The crops are alfalfa, timothy, clover, green-cut grain, barley, oats, wheat and a little potato, mostly grown for feed. Dairying depends on enough cultivated land for winter forage (1938, Part One).
20. Orchards did not thrive, and fumigation is claimed to be one reason. The Upper Columbia Company bought about ten thousand acres in 1909-1910 and planted a 900-acre orchard at Marble. By 1917 the project had failed (1938, Part One).
21. In 1896 a smelter was started under American auspices near Trail. In 1906 the Consolidated Mining and Smelting Company of Canada, Limited, was incorporated in Canada and acquired it. The company has run it without a break and enlarged it into one of the best-equipped smelting plants on the continent (1938, Part One; 1941, Part One, II).
22. In 1925 and 1927 two stacks were raised to 409 feet and daily smelting of zinc and lead ores greatly increased. That put more sulphur dioxide into the air at higher concentrations. One side claimed, and the other denied, that the taller stacks widened the damaged area in the United States (1938, Part One).
23. Sulphur emitted was about 5,000 tons a month in 1916, 4,700 in 1924 and 9,000 in 1926. It rose near 10,000 tons a month in 1930, about 300 to 350 tons a day. One ton of sulphur is roughly two tons of sulphur dioxide (1941, Part One, II; 1938, Part One).
24. Damage occurred in Washington from the sulphur dioxide of the Trail Smelter from at least 1925. The 1941 decision says this continued to 1937, as the 1938 decision stated (1938, Part One; 1941, Part One, II).
25. From 1925, and perhaps earlier, suggestions were made to the smelter that property in northern Stevens County was being damaged. J. H. Stroh made the first formal complaint in 1926. Others followed (1938, Part One).
26. The company investigated and became convinced damage had been and was being done. It settled with a number of farmers over about two years (1938, Part One).
27. In June 1928 the Stevens County Commissioners passed a resolution on the fumigations. On 25 August 1928 the Citizens' Protective Association was formed. Its articles barred any member from settling without written consent of a majority of its Board. After that no individual settlements were made (1938, Part One).
28. A contention was made that Washington's Constitution or a statute stopped a Canadian corporation from acquiring land or smoke easements in Washington. The Tribunal expressed no opinion on that point, as to fact or law (1938, Part One).
29. From 1931 the company installed three 112-ton sulphuric acid plants and an ammonia and ammonium sulphate plant. It added two units to reduce and absorb sulphur in the zinc smelter (1936 and 1937) and an absorption plant for lead roaster gases (June 1937). It began a crop-season fume control system, in operation particularly since May 1934 (1938, Part One).
30. Sulphur emitted fell from about 10,000 tons a month in 1930 to about 7,200 in 1931 and 3,400 in 1932. It then rose to 4,000 in 1933, nearly 6,300 in 1934 and 6,800 in 1935. It was 5,600 in 1936 and 4,750 for January to July 1937 (1938, Part One).
31. The 1941 decision gives later figures: 4,850 tons a month in 1937, 4,230 in 1938, 3,250 in 1939 and 3,875 in 1940 (1941, Part One, II).
32. By 1941 five sulphuric acid plants gave 600 tons of acid a day, fixing about 200 tons of sulphur a day if run at capacity. Three units made elemental sulphur from 1936 at 140 tons a day. Absorption capacity was 600 tons of sulphur dioxide a day (300 from zinc and 300 from lead plant gases) (1941, Part One, II).
33. In 1939, 360 tons of sulphur a day were oxidised to sulphur dioxide, and 253 tons were used. In 1940, 416 tons were oxidised and 289 used. 107 tons a day in 1939 and 127 in 1940 went into the air (1941, Part One, II).
34. Recorders were kept by both sides. The United States had them at Northport (1932 to 1937), Boundary, Evans and Marble, and a portable one at Fowler Farm in 1939 and 1940. Canada kept them at Stroh Farm, opposite Northport, Waneta and Columbia Gardens (1941, Part One, II).
35. The 1941 decision tabulates fumigation hours at Northport and Waneta for the growing seasons of 1938 to 1940, by concentration band (0.11 to 0.25, 0.26 to 0.50 and above 0.50 parts per million). The highest Waneta reading in the 1938 table was 1.63 p.p.m. in August 1938 (1941, Part One, II).

Issues Raised

The Convention set four Questions. The Tribunal was to finally decide them (Convention, Article III; 1938, introduction; 1941, introduction).

1. Has damage caused by the Trail Smelter in the State of Washington occurred since 1 January 1932, and if so, what indemnity should be paid for it (Question 1)? (Convention, Article III)
2. If so, should the Trail Smelter be required to refrain from causing damage in Washington in the future, and if so, to what extent (Question 2)? (Convention, Article III)
3. In the light of that answer, what measures or régime, if any, should the Trail Smelter adopt or maintain (Question 3)? (Convention, Article III)
4. What indemnity or compensation, if any, should be paid on account of the decisions on Questions 2 and 3 (Question 4)? (Convention, Article III)

The Tribunal also had to decide these points that arose within Question 1 and Question 2:

5. For 1932 onward, did injury exist, what caused it, and what damage was due to it? (1938, Part Two)
6. Was damage proved for each class claimed: cleared land, uncleared land and timber, livestock, Northport town property, business enterprises, and slag and water? (1938, Part Two)
7. Is the United States entitled to damages for violation of sovereignty and to its investigation costs, either separately or as incident to other damages? (1938, Part Two, clause 7)
8. Must interest on $350,000 be paid? (1938, Part Two, clause 8)
9. Is the 1938 decision on Question 1 for the period to 1 October 1937 res judicata (a final, binding decision)? (1941, Part Two, I)
10. Does the Convention deny the Tribunal power to revise that decision, and should a revision petition for an alleged error of law be entertained and granted? (1941, Part Two, I)
11. Did damage occur from 1 October 1937 to 1 October 1940, and what indemnity is due? (1941, Part Two, II (a))
12. Can the United States recover its investigation costs from July 1936 to September 1940? (1941, Part Two, II (b))
13. Under which law should Question 2 be answered, and what duty does a State have for fumes from its territory? (1941, Part Three)
14. What permanent régime should apply, and may it be amended or suspended later? (1941, Part Four)
15. What indemnity or compensation follows from the answers to Questions 2 and 3, and what rights of investigation should be preserved? (1941, Parts Five and Six)

Arguments Contended

The award records the parties' arguments in pieces. Arguments are listed with the decision and Part that records them. Neither side's pleadings are set out in full.

For the United States

• Sulphur dioxide fumes from the Trail Smelter, travelling down the Columbia valley and otherwise, entered the United States and caused damage (1938, Part Two).
• Damages of $1,849,156.16 plus interest of $250,855.01, total $2,100,011.17, were claimed in seven categories. The categories were:
  • (a) cleared land and improvements;
  • (b) uncleared land and improvements;
  • (c) livestock;
  • (d) property in Northport town;
  • (e) wrong done to the United States in violation of sovereignty, measured by investigation cost from 1 January 1932 to 30 June 1936;
  • (f) interest on $350,000;
  • (g) business enterprises.
• The area claimed exceeded 140,000 acres (1938, Part Two; 1941, introduction).
• In its itemised schedule the United States divided the properties of individual farmers into classes: farmers living on their farms, farmers not living on them, farmers driven from their farms, and large owners (1938, Part Two, clause 1). The Tribunal did not adopt this division.
• Damage to improvements should be assessed separately from the land (1938, Part Two, clause 1).
• Damage to uncleared land should be measured by applying to its value the ratio of loss from reduced crop yield on cleared land. For timberland the value stated by the farmers, less the timber, should be so reduced (1938, Part Two, clauses 2 and 2(B)).
• Fumigation prevents germination of seed and prevents trees from producing seed (1938, Part Two, clause 2(B)(c)).
• Livestock, milk and wool productivity were injured through impaired crop or grazing quality (1938, Part Two, clause 3).
• Town property in Northport suffered damage, to be calculated by the United States' method (1938, Part Two, clause 4).
• Business men suffered lost business and good will because of the reduced economic status of residents. Counsel relied on authorities at pages 412 to 423 of the Answer and Argument (1938, Part Two, clause 5).
• The smelter disposes of slag so that it reaches the Columbia River and enters the United States. The river waters in Stevens County are injuriously affected (1938, Part Two, clause 6).
• Investigation costs are damages for violation of sovereignty. The Agent, Mr. Sherley, also argued that costs and interest are incident to the damage and go with the award (1938, Part Two, clause 7).
• The United States cited international cases awarding expenses and United States court cases where expenses were ordered paid (1938, Part Two, clause 7).
• Interest on $350,000 was due because payment came on 2 November 1935 and not on 1 January 1932 (1938, Part Two, clause 8).
• In 1941 the United States asked the Tribunal to reconsider the 1938 decision on expenditures from 1 January 1932 to 30 June 1936. It claimed $89,655 with five per cent interest on each year's sum to the date of final decision (1941, Part Two, I).
• It did not argue that the 1938 decision was void for excess of power. It asked for reconsideration for a material error of law (1941, Part Two, I).
• The alleged errors were three. First, excluding investigation costs from damage caused by the Trail Smelter (Article III(1)). Second, the statements about the I'm Alone award and expenses of individual claimants, which the United States conceded might be dicta. Third, failing to reach a solution just to all parties concerned under Article IV (1941, Part Two, I).
• Reliance was placed on the Sabotage cases dictum of Umpire Justice Roberts, that a decision with a material error of law may be reopened. The United States had also proposed at the first Hague Conference a right to a second hearing for new witnesses or questions of law (1941, Part Two, I).
• For the period after 1 October 1937, the United States claimed $34,807. It alleged acute damage in about 6,000 acres and secondary damage in about 27,000 acres in 1938 to 1940, and damage in Northport town (1941, Part Two, II (a)).
• The rate claimed was $0.8525 an acre in the acute area and $1.0511 an acre in the secondary area, on all land whether cleared or not. Damage for 1932 to 1937 was put at $17,050 (acute), $189,200 (secondary) and $8,750 (Northport). Damage for 1938 to 1940 was taken as 0.3 of the first and 0.15 of the others (1941, Part Two, II (a)).
• The United States claimed $38,657.79 for expenses from 1 July 1936 to 1 September 1940, with five per cent interest. It argued that where injury is caused and its continuance is feared, investigation costs are a damageable consequence just as damage to crops and trees (1941, Part Two, II (b)).
• It argued the terms of reference to this Tribunal, unlike those to the International Joint Commission, are not limited to property (1941, Part Two, II (b)).
• It said no precedent is known for an award of a Government's own investigation costs. Its counsel admitted this when asked (1941, Part Two, II (b)).
• On Question 2, it refused to accept the Joint Commission's definition of damage. It said that as long as fumigations occur in Washington with frequency, duration and intensity enough to cause injury, there are grounds of complaint regardless of the remedial works. It cited its letter of 30 January 1934 (1941, Part Three).
• It suggested a régime in which a fixed sum would be due whenever recorded concentrations exceeded a set intensity for a set time, or a greater intensity for any twenty-minute period (1941, Part Four, Section 2).

For Canada

• Even if fumes entered the United States, they caused no damage after 1 January 1932 (1938, Part Two).
• Its witnesses said forest injury was mainly due to insects, disease, winter and summer droughts, unwise logging, and forest and ground fires (1938, Part Two).
• The principle that a State owes a duty to protect other States against injurious acts from its territory has not been questioned by Canada (1941, Part Three).
• Canada said the slag and water item was outside damage caused by the Trail Smelter in Article III. It rested this on the preamble, which refers only to fumes discharged from the Smelter (1938, Part Two, clause 6).
• Canada had said, in a letter of 22 February 1934, that it would be entirely satisfied to refer the Tribunal to the principles of law as recognized and applied by the courts of the United States of America in such matters (1941, Part Two, I).
• In correspondence Canada wished the Joint Commission's report adopted, including its exclusion of occasional damage caused by air pockets or unusual atmospheric conditions (1941, Part Three).
• Canada used Mr. G. J. Bayle's timber cruises as evidence (1938, Part Two, clause 2(B)).
• Canada's Agent and counsel praised the trial period. In a memorandum of 28 December 1940 Canada said it did not question its value, though it commented on the expense. Counsel Mr. Tilley agreed the Tribunal's course in 1938 was in the interests of the parties concerned (1941, Part Four, Section 4).
• The Tribunal does not record any argument of Canada against the 1941 revision petition beyond the res judicata point the Tribunal itself raised. It does not set out Canada's reply to the $34,807 claim in detail (1941, Part Two).

Tribunal's Reasoning

The Tribunal gave two decisions, each signed by all three members. No member wrote a separate, concurring or dissenting opinion, so each decision has its own subsection below. The award has no numbered paragraphs, so each step cites the decision and its Part.

1938 decision — the Tribunal (Jan Hostie, Chairman; Charles Warren; R. A. E. Greenshields): powers, law and approach

1. Noted: the Tribunal is set up under the Convention, and its powers come from it and are limited by it. The Convention was signed at Ottawa on 15 April 1935 and ratified on 3 August 1935 (1938, introduction).
2. Noted: wherever the Tribunal referred to United States court decisions or followed American law, it acted under Article IV of the Convention (1938, introduction).
3. Noted: the Tribunal was guided by the aim in Article IV of "a solution just to all parties concerned". It was also guided by the need for a permanent settlement in the opening paragraph of the Convention (1938, introduction).
4. Held: the controversy is between two Governments over damage in the territory of one (the United States) alleged to come from an agency in the other (Canada). Canada assumed international responsibility for that damage by the Convention (1938, introduction).
5. Held: the Tribunal does not sit to decide claims of individuals, or claims brought for individuals by their Government. Individuals may still be parties concerned in Article IV and interested parties in Article VIII. Their damage may serve as a convenient scale for working out the reparation due to the State (1938, introduction).
6. Noted: for this last point the Tribunal cited the Permanent Court of International Justice, Judgment No. 13, Series A, No. 17, pages 27 and 28 (1938, introduction).
7. Noted: the Tribunal was ready to decide Question 1 finally. It gave a temporary decision on Questions 2 and 3, set up a temporary régime, and kept the final decision on those Questions and on Question 4 for three months from 1 October 1940 (1938, introduction).

1938 decision — Part One: background the Tribunal described

1. Noted: the Tribunal gave a general account of the locality, its climate and its economic history as an introduction to its decision. The account is in the Facts section (1938, Part One).
2. Noted: the Tribunal described the earlier Northport smelter and held there was no doubt that it caused damage over a restricted area. It also noted the smoke easements bought by that company and the suits in Stevens County courts (1938, Part One).
3. Held: from at least 1925 to the end of 1931, damage occurred in Washington from sulphur dioxide emitted by the Trail Smelter (1938, Part One).
4. Noted: the record does not show details of claims for the 1896 to 1908 fumigations. It does show that the company convinced itself damage had been done and settled with some farmers until the Citizens' Protective Association stopped settlements (1938, Part One).
5. Noted: on whether Washington's Constitution or a statute stopped the Canadian company from owning land or smoke easements, the Tribunal expressed no opinion and made no ruling (1938, Part One).
6. Noted: the International Joint Commission's report was unanimous and the Tribunal did not consider it in detail. The Tribunal observed that its recommended method for claims after 1 January 1932 did not suit the interested parties, and no claims were made under it (1938, Part One).
7. Noted: whatever the company's General Manager represented to the Commission about building sulphuric acid units, the testimony conflicted, and the Tribunal found it unnecessary to resolve it. The company went on after 1930 to make the changes listed in the Facts (1938, Part One).

1938 decision — Part Two: Question 1, existence, cause and extent of damage

1. Held: the Tribunal had to consider three points. They were the existence of injury, the cause of injury and the damage due to the injury (1938, Part Two).
2. Held: the word occurred covers damage caused before 1 January 1932 so far as its effect made itself felt after that date. Trail Smelter means the Consolidated Mining and Smelting Company of Canada, Limited, its successors and assigns (1938, Part Two).
3. Noted: on the indemnity, the Tribunal kept in mind the United States rule in Story Parchment Company v. Paterson Parchment Paper Company. Where a tort prevents exact proof of damages, the injured person must not be denied all relief. Damages need not be shown by mere speculation. It is enough if the evidence shows the extent as a just and reasonable inference, even if only approximate (1938, Part Two).
4. Noted: the Tribunal also referred to Allison v. Chandler, quoted with approval by the United States Supreme Court. Refusing damages for want of certainty would give "the certainty of injustice" (1938, Part Two).
5. Held: damage due to fumigations was proved to have occurred since 1 January 1932 on cleared and uncleared land, to the extent set out below (1938, Part Two).
6. Noted: the Tribunal made five general remarks on the evidence on cause. First, the recorder data from 1931 to 1937 was of great value (1938, Part Two, remark 1).
7. Noted: second, the Wenatchee (United States) and Summerland (Canada) experiments on crops helped. The Canadian ones were more extensive and better conducted. The number of experiments was still too limited for the positive conclusions some witnesses drew. Experimental plots can rarely reproduce field conditions, and injury sometimes occurred in the field at levels that never harmed the plots (1938, Part Two, remark 2).
8. Noted: third, field observations were not continuous, did not cover all the area of probable damage, and were not made simultaneously or compared by the experts of the two sides (1938, Part Two, remark 3).
9. Noted: fourth, the poor condition of the trees was not disputed, but experts disagreed on cause. United States witnesses blamed sulphur dioxide. Canadian witnesses blamed insects, disease, droughts, logging and fires. Each side may have stressed its own cause too much (1938, Part Two, remark 4).
10. Noted: fifth, the soil and water tests were too limited to give absolutely positive conclusions (1938, Part Two, remark 5).
11. Noted: the Tribunal found the witnesses honest and sincere and the experts skilled. It cited Judge Johnson in Anderson v. American Smelting and Refining Co.: opinion witnesses may be unconsciously influenced by their point of view. Their real value lies in describing appearances and surroundings, not in their ultimate opinions (1938, Part Two).
12. Held: the Tribunal could not accept the theory, common to witnesses of both Governments, that surface winds carried the gas. It adopted a more probable theory (1938, Part Two).
13. Why: recorder data showed fumigations occurring almost simultaneously at points many miles apart in the growing season. The rate of gas attenuation down the river was uneven: faster in the first few miles below the boundary, slower further down. Surface winds could not explain these facts or the timing and duration of fumigations (1938, Part Two).
14. Held: the gases from the stacks enter the upper air currents. They are carried down the valley in a fairly continuous stream while the prevailing wind at that level blows that way (1938, Part Two).
15. Noted: the 1929 United States Weather Bureau data at Northport showed the prevailing direction at 5 a.m. to be north-east up to 600 metres, at 2 to 5 miles an hour. Above that it is south-west, shifting to west-south-west and west, and speeds rise to about 30 miles an hour at about 700 metres (1938, Part Two).
16. Held: fumigations along the valley are caused by this upper air stream mixing with the surface air. The height of the stream was yet to be fixed. Mixing follows recognised meteorological laws and depends mainly on two factors. They are the temperature differences between surface and upper air (the temperature gradient) and the difference in velocity between upper air and surface air currents (1938, Part Two).
17. Held: the most frequent fumigations in late spring, summer and early autumn are diurnal (daily). They occur in the early morning, are short, and are driven by the rising sun heating the surface air. That heating causes the mixing, and a fumigation is recorded at every station the gas reaches in measurable concentration (1938, Part Two).
18. Noted: the sun's effect may differ on the east and west sides of the valley. The Tribunal said that must await further study (1938, Part Two).
19. Held: winter fumigations are not strictly diurnal and are usually longer. They are due to a gas-carrying air current with enough velocity, for a long enough time, to mix with the surface air. Whether it causes a fumigation depends on how fast surface winds dilute the surface air. They are more common at night, when surface winds drop (1938, Part Two).
20. Held: sulphur dioxide concentration falls very rapidly from Trail to a point about 16 miles downstream (6 miles from the boundary by the river). Beyond that it is lower and falls more gradually (1938, Part Two).
21. Noted: fumigations sometimes occur in rainy or humid weather. The Tribunal said that might be more than a coincidence but it was not prepared to offer an opinion (1938, Part Two).
22. Noted: these conclusions bear on the cause and degree of damage and the area of probable damage (1938, Part Two).
23. Held: cleared land used for crops. Crop yield was reduced by fumigation in varying degrees in each of 1932 to 1936. No damage was proved for 1937 (1938, Part Two, clause 1).
24. Held: with a possible exception for a few very exposed farms, damage in the worst year did not go beyond these limits. They are the Boundary and Northport precincts (possibly excluding some eastern Boundary and western Northport properties), parts of Cummins and Doyle precincts on or near the river benches, part of Marble precinct north of the southern limit of Sections 22, 23 and 24 of T. 39, R. 39, and part of Flat Creek precinct on or near the benches (1938, Part Two, clause 1).
25. Held: the Tribunal did not adopt the United States' division of farmers into classes (1938, Part Two, clause 1).
26. Held: the measure of indemnity for cleared crop land is the one American courts apply in nuisance (harm to the use or enjoyment of land) or trespass: the fall in the value of the use or rental value of the land. For farm land this is generally the fall in crop yield less marketing cost, which was negligible here. Failure to increase seeded land may be considered (1938, Part Two, clause 1).
27. Noted: the Tribunal cited Ralston v. United Verde Copper Co. for that measure (1938, Part Two, clause 1).
28. Noted: the difference between probable yield without fumigation and actual yield is uncertain and cannot be proved absolutely. The Tribunal based its estimate on fumigation records, meteorological data, crop statistics inside and outside the area and Census records (1938, Part Two, clause 1).
29. Held: abandoned properties and the failure of farmers to increase seeded land were handled by estimating from statistics the acreage that would probably have been seeded and harvested but for fumigation. Almost all properties listed as abandoned in the questionnaire sent by the former United States Agent, Mr. Metzger, were abandoned before 1932 (1938, Part Two, clause 1).
30. Held: no damage to orchards from fumigation within the damaged area was proved (1938, Part Two, clause 1).
31. Held: injury to soil from increased acidity was not proved, with one exception. A small farming area west of the river next to the boundary suffered serious acidity from fumigations. Since the effect may be continuing, American law measures damage there by the fall in the value of the land itself (Sedgwick on Damages, 9th ed. 1920, Section 932 and Section 947). The Tribunal held such soil injury can be cured by artificial means and fixed the indemnity on that footing (1938, Part Two, clause 1).
32. Held: about forty farms near the boundary received an additional indemnity for reduction in the value of use or rental value because of their location in relation to the fumigations. The Tribunal cited Baltimore and Potomac R.R. v. Fifth Baptist Church (1883) (1938, Part Two, clause 1).
33. Held: American law does not allow damage to improvements to be assessed separately from the land. Any non-physical injury to improvements is covered by the general award for reduction in the value of use (1938, Part Two, clause 1).
34. Held: some owners suffered rust and destruction of metal work. There was slight evidence and none on extent or amount, so the indemnity for it is nominal for each owner (1938, Part Two, clause 1).
35. Held: for cleared land not used for crops and uncleared land (other than timber), the measure is again the fall in value of use or rental value. The United States' method of applying the cleared-land crop loss ratio to uncleared land has no support in American decisions (1938, Part Two, clause 2).
36. Held: for pasture, there was no evidence of marked susceptibility of wild grasses and little evidence of amounts and values. The Tribunal awarded a small indemnity for about 200 acres in the immediate neighbourhood of the boundary (1938, Part Two, clause 2(A)).
37. Held: it was impossible to say whether limited soil erosion and loss of water storage capacity near the boundary came from fires or from tree and shrub mortality caused by fumigation (1938, Part Two, clause 2(A)).
38. Held: damage to trees occurred from 1932 to 1937. Its extent varied by year and species, and no exact area could be fixed. Broadly, the area covered by the Bayle cruises is an average area. Damage near the boundary was somewhat wider, and below Marble injury was confined to the river's immediate vicinity, except to larch in 1936 (1938, Part Two, clause 2(B)).
39. Noted: for many years before 1 January 1932 much of the forest in Northport and Boundary precincts was in poor condition from serious fires and the earlier Northport smelter operations, 1898 to 1901, 1901 to 1908 and 1916 to 1921. Washington courts had decided suits on those claims. Heavy fumigations from Trail in 1930 and 1931 destroyed and injured trees, and earlier ones were serious too (1938, Part Two, clause 2(B)).
40. Noted: the Tribunal listed four Washington cases not cited by counsel: Sterrett v. Northport Smelting and Refining Co. (1902), Rowe v. the same company (1904), Park v. the same (1907) and Johnson v. the same (1908) (1938, Part Two, clause 2(B)).
41. Noted: the Deans' Report of September 1929 said no timber cruise had been made by a forest engineer of either Government. It said serious damage to timber had taken place and reproduction was impaired. It recommended a check cruise by an American forest engineer by summer 1930, and it called the 1927-1928 Canadian company cruise satisfactory subject to a check. The United States made no 1930 cruise (1938, Part Two, clause 2(B)).
42. Noted: the Washington Forest Survey Release No. 5 (June 1937) classed most of the land as non-restocked old burns and cut-overs, or immature forest on recent burns and cut-overs, with woodland that is not commercial timber. G. J. Bayle's reports described much timber as far from transport, of little commercial value, scattered and on steep slopes. The Release records 52,402 acres recently deforested and 77,650 acres with slight natural regeneration, much of that thought to be the effect of alleged smelter fume damage (1938, Part Two, clause 2(B)).
43. Held: for merchantable timber, American courts measure damage by the fall in value of the land itself. The value of the merchantable timber destroyed is in general the equivalent (Sedgwick on Damages, 9th ed. 1920, Section 937a). The Tribunal rejected the United States' method of applying the cleared-land crop loss ratio to the farmers' stated land value less timber (1938, Part Two, clause 2(B)(a)).
44. Held: in line with American law, the Tribunal is not tied to the claimant's method of fixing damages so long as its findings stay within the amount claimed (1938, Part Two, clause 2(B)(a)).
45. Noted: the Tribunal had an unnecessarily hard task because neither Government made a timber cruise as of 1 January 1932. The affidavits of landowners filed in 1929 gave only earlier figures. The Tribunal used Bayle's 1927-1928 cruise, the most detailed, and his 1936 and 1937 cruises, allowing for destruction by fire, fumigation and insects and for trees that became merchantable (1938, Part Two, clause 2(B)(a)).
46. Held: for growing timber not yet of merchantable size, damage is the fall in the value of the land itself. No evidence gave the locations, amounts or types of that timber. Some damage undoubtedly occurred but could not be estimated, so the Tribunal took it into account in awarding for land with growing timber (1938, Part Two, clause 2(B)(b)).
47. Held: the United States' contention that fumigation prevents seed germination was not sustained. Hedgcock's studies showed seedlings were injured after germination by drought or fumes, but germination took place (1938, Part Two, clause 2(B)(c)).
48. Held: it was not proved that fumigation prevents trees from producing enough seed, except where the parent trees are themselves destroyed or deteriorated. The Hedgcock cone production studies on yellow pine support this (1938, Part Two, clause 2(B)(c)).
49. Held: loss of reproduction due to death or impairment of parent trees before 1 January 1932 was caused and occurred before that date. Douglas fir and yellow pine rarely germinate more than a year after seeding and give a good seed crop only once in several years. Loss from trees killed in 1931 is too speculative to support an award (1938, Part Two, clause 2(B)(c)).
50. Held: there is a general lack of reproduction of yellow pine and Douglas fir over a fairly large area, and fumigation contributes. It is impossible to tell how much is due to fumigation rather than repeated fires or logging, or how much traces to tree death after 1 January 1932 (1938, Part Two, clause 2(B)(c)).
51. Noted: lodgepole pine, cedar and larch are reproducing in places. Standard forestry works say yellow pine reproduces patchily, is often replaced by another species after destruction, and does not thrive where rainfall is little above eighteen inches. Northport averaged slightly under seventeen inches. No quantitative data existed, but the Tribunal took lack of reproduction into account to some extent (1938, Part Two, clause 2(B)(c), with its footnote).
52. Held: the indemnity was $62,000 for cleared land and uncleared land other than timber, and $16,000 for uncleared land used for timber, a total of $78,000 for 1 January 1932 to 1 October 1937 (1938, Part Two, clause 2).
53. Held: livestock. The United States failed to prove that fumes injured livestock or their milk or wool productivity through impaired crop or grazing quality. Injury from reduced crop or grazing yield is covered by the award for reduced yield (1938, Part Two, clause 3).
54. Held: Northport town property. The same measure applies to urban land. There was no proof of damage and no proof of facts to estimate it. The Tribunal could not adopt the United States' method of calculating urban damage (1938, Part Two, clause 4).
55. Held: business enterprises. Damage due to reduced economic status of residents is too indirect, remote and uncertain to be appraised, and no indemnity can be awarded. No case cited by counsel supports an indemnity for loss of business because customers cannot buy. Also, the burden of proof (the duty to prove a point) that any such damage was due to Trail fumes was not met, and an award would be speculative (1938, Part Two, clause 5).
56. Held: slag and water. No evidence was given on which the Tribunal could make findings. On Canada's contention that this item is outside damage caused by the Trail Smelter, the Tribunal said it was not incumbent on it to rule at that time (1938, Part Two, clause 6).
57. Held: violation of sovereignty (Item e). The Tribunal found it unnecessary to decide whether the facts violated United States sovereignty under international law apart from the Convention. The only question was how to read the Convention (1938, Part Two, clause 7).
58. Held: the United States itemised this claim only as money spent on its Government's investigation. The words damage caused by the Trail Smelter in Article III were not meant to include those sums. The proceedings and diplomatic correspondence before the Convention confirm this (1938, Part Two, clause 7).
59. Noted: the Tribunal did not decide whether other damage for violation of sovereignty could have been awarded if specifically alleged. The case did not involve the type of facts for which damages for violation of sovereignty were awarded to Canada in the I'm Alone award of 5 January 1935. In other international cases cited, expenses were awarded as compensation for individual claimants' expenses, not for national sovereignty (1938, Part Two, clause 7).
60. Held: the Tribunal rejected Mr. Sherley's argument that costs and interest are incident to damage. Costs may be suitable as an incident in cases of damage to individual claimants. They should not be allowed in an arbitration and final settlement between two independent Governments, each of which has incurred expenses and both of which benefit from a just, permanent settlement (1938, Part Two, clause 7).
61. Held: the United States court cases where expenses were ordered paid are inapplicable. Neither as a separate item nor as an incident should anything be awarded for violation of sovereignty (1938, Part Two, clause 7).
62. Held: interest on $350,000. The Convention did not contemplate interest. By paying within the time Article I provided, Canada fully met its obligation, so interest cannot be allowed (1938, Part Two, clause 8).
63. Held: Question 1 is answered as follows. Damage caused by the Trail Smelter in Washington occurred from 1 January 1932 to 1 October 1937. The indemnity is $78,000, complete and final for all damage in those dates. Interest at six per cent a year runs on it from the filing of the report until payment. The decision cannot be altered by the Tribunal later (1938, Part Two, conclusion).
64. Noted: damage after 1 October 1937 and its indemnity were left for the final decision (1938, Part Two, conclusion).

1938 decision — Parts Three and Four: Questions 2 and 3 (temporary decision)

1. Held: until the final decision, the Trail Smelter must refrain from causing damage in Washington in the future. For the period to 1 October 1940 the extent is as set out in Part Four, and afterwards as the Tribunal requires in its final decision (1938, Part Three).
2. Held: the Tribunal could not yet fix a permanent régime on the information before it (1938, Part Four).
3. Why: from its conclusions on the nature, cause and course of fumigations and the data collected, it could predict with some assurance a result. A permanent régime based on more intensive study of meteorological conditions, and on better plant methods and control tied to those conditions, would effectively prevent future significant fumigations in the United States. It would do so without unreasonably restricting output (1938, Part Four).
4. Held: to reach that régime the Tribunal set up a temporary régime to run to a date not later than 1 October 1940. The directions are stated in the Award section (1938, Part Four, clauses 1 to 11).
5. Noted: the 1938 temporary régime itself rests on these stated aims. Observations by meteorologists and equipment at the stacks were to give data on air conditions. The régime was to be as flexible as possible and open to change as circumstances required (1938, Part Four, clause 3(f)).
6. Noted: the limits on sulphur emission from 1 May to 1 October 1938 were interim measures only. The Tribunal said it was not at present ready to make such limitations permanent but thought they would for the present probably lessen the chance of injury in the area (1938, Part Four, clause 9).
7. Held: nothing in Part Four relieved Canada of any existing Convention obligation about indemnity for damage between 1 October 1937 and 1 October 1940 or the earlier date of the final decision (1938, Part Four, end).

1941 decision — the Tribunal (Jan Hostie, Chairman; Charles Warren; R. A. E. Greenshields): introduction and approach

1. Noted: the Tribunal reported its final decisions. It again recorded that it did not sit to pass on claims of individuals or claims brought for them by their Government. It said that what it had said in the 1938 decision (Part Two, clause 1) on abandonment of properties bears on this (1941, introduction).
2. Held: as between the two countries each has an equal interest. If a nuisance is proved, indemnity must be just and adequate. Unproven or unwarranted claims must not be allowed. A Canadian corporation may injure United States interests now, but American corporations may injure Canadian interests later (1941, introduction).
3. Noted: the Tribunal quoted a saying that it would not serve the two countries to prevent industrial effort by exaggerating the interests of farmers, or to oppress farmers to advance industry (1941, introduction).
4. Held: the phrase a solution just to all parties concerned in Article IV, and the wording of the Questions, show an intent that the Tribunal adjust conflicting interests. The smelter may continue operating under restrictions that prevent foreseeable damage in the United States, and indemnity should be obtainable if damage occurs despite them (1941, introduction).
5. Noted: the Tribunal also bore in mind the preamble's desirability and necessity of effecting a permanent settlement (1941, introduction).
6. Noted: the Tribunal recounted the 1937 sittings and the 1938 extension and decision. In the United States statement, damages of $1,849,156.16 and interest of $250,855.01 (total $2,100,011.17) were claimed. The Tribunal disallowed items (c), (d), (e), (f) and (g) and allowed items (a) and (b) in part (1941, introduction).
7. Noted: the 1941 decision restates the locality, economy, smelter history, IJC history and the plant changes and recorder data, with updated figures to 1940 (1941, Part One, I and II).
8. Noted: the Tribunal restated that damage occurred in Washington from at least 1925 to 1937 as stated in the previous decision (1941, Part One, II).

1941 decision — Part Two, I: the request to reconsider the 1938 decision (res judicata and revision)

1. Noted: the United States asked the Tribunal to reconsider its disallowance of $89,655. This was investigation expenditure, with interest, for 1 January 1932 to 30 June 1936 (1941, Part Two, I).
2. Held: the $78,000 awarded was paid by Canada and received by the United States without reservation. The decision was thus complied with under Article XII. The decision had finality in itself, even without this action by the parties (1941, Part Two, I).
3. Why: Article XI speaks of final decisions reported as soon as it has reached its conclusions in respect to the questions. Article XII binds the Governments to comply. The 1938 decision said it was "not subject to alteration or modification by the Tribunal hereafter" (1941, Part Two, I).
4. Noted: it might be argued that final decisions in Article XI become final only when all Questions are answered. The Tribunal did not act only on its own reading. It told the Governments its intention to award damages to 1 October 1937 while ordering further investigation. Both agreed to the extension on that understanding in letters of 14 March 1938 and 22 March 1938 (1941, Part Two, I).
5. Why: this reading does not conflict with the Convention. Further investigation after the hearing was not foreseen. The duty to reach a solution just to all parties could not be met by a permanent régime on inadequate data. Equity would also not be served by withholding damages for over two and a half years (1941, Part Two, I).
6. Noted: the Tribunal then considered whether its decision to 1 October 1937 is res judicata (a final decision that cannot be reopened) (1941, Part Two, I).
7. Noted: in the absence of an agreement excluding international law and laying down the law to apply, international law is the law of an international tribunal. The Tribunal cited Dr. James Brown Scott, Hague Court Reports (1941, Part Two, I).
8. Held: an international tribunal may apply national law, but will not depart from the rules of international law in favour of divergent national rules unless refusing would clearly go against the treaty-makers' expressed intention. This applies particularly to procedure (1941, Part Two, I).
9. Noted: Article 16 of the Tribunal's rules, adopted with both Agents' concurrence on 22 June 1937, shows how the Tribunal and the Agents understood Article IV (1941, Part Two, I).
10. Held: Article IV does not bind the Tribunal to apply national law and practice to the exclusion of international law and practice (1941, Part Two, I).
11. Held: the words the law and practice followed in the United States are limited by in dealing with cognate questions. These are questions of damage caused by smelter fumes, indemnity and régime, which may be questions of law or practice. General questions such as the authority of res judicata and its exceptions are not cognate questions (1941, Part Two, I).
12. Noted: the correspondence confirms this. On 22 February 1934 Canada was entirely satisfied to refer the Tribunal to principles of law applied by United States courts. The surrounding text shows cognate matters meant mainly questions that between private parties are answered by the law of nuisances (1941, Part Two, I).
13. Held: it is an essential and settled rule of international law that the sanctity of res judicata attaches to a final decision of an international tribunal. If international relations based on law and justice need adjudication, the adjudication must in principle remain unchallenged (1941, Part Two, I).
14. Noted: Pious Funds of California (14 October 1902). The tribunal held the claim was governed by res judicata through Sir Edward Thornton's earlier award (1941, Part Two, I).
15. Noted: Fabiani case (French-Venezuelan Claims Commission, Umpire Plumley). A declaration of incompetency, as in the Swiss President's earlier award, did not leave the matter open. The earlier award was a complete, final and conclusive disposition of the controversy (1941, Part Two, I).
16. Noted: Orinoco Steamship Company (25 October 1910). It said it is in the interest of peace and arbitration that a decision in principle be accepted, respected and carried out without reservation (1941, Part Two, I).
17. Noted: the Permanent Court of International Justice based the legal effect of arbitral decisions on res judicata in Advisory Opinions No. 8 (Jaworzina), No. 9 (Monastery of Saint Naoum) and No. 11 (Polish Postal Service in Danzig), all Series B (1941, Part Two, I).
18. Noted: the Permanent Court in the Société Commerciale de Belgique case (Series A/B, No. 78) said awards final and without appeal can be neither confirmed nor annulled by it. The United States Supreme Court in Frelinghuysen v. Key said the awards of the United States-Mexican Claims Commission were final and conclusive until set aside by agreement or otherwise (1941, Part Two, I).
19. Held: there is no doubt res judicata applies here. The three traditional elements of identity, parties, object and cause, are the same (1941, Part Two, I).
20. Noted: under Article 59 of the Statute of the Permanent Court, its decisions bind only the parties and the particular case. In the Chorzow case, Judgment No. 11, the Court found res judicata force even in an incidental decision on a preliminary point. The minority judge Anzilotti said incidental decisions do not bind in another case. Judge Ehrlich adopted this view in Judgment No. 13. Anzilotti did not expressly answer whether the rule covers an indemnity action after a declaratory judgment (1941, Part Two, I).
21. Noted: when Chorzow came up on indemnity in Judgment No. 13, the Court appeared to avoid asserting res judicata, as Ehrlich pointed out. Yet it said the Oberschlesische's right to the factory could not be looked at differently for the earlier judgment and for the claim for reparation, so in effect it was bound by its earlier decision (1941, Part Two, I).
22. Held: the 1938 decision was not preliminary or incidental, and not a decision on jurisdiction. Tiedemann v. Poland supports the view that a decision only on jurisdiction may be reversed by the same court. Even if that is right, it does not affect this case, as in Fabiani the decision did not deny jurisdiction (1941, Part Two, I).
23. Noted: the United States does not contend the 1938 decision is void for excess of power. It asks for reconsideration and revision on account of a material error of law (1941, Part Two, I).
24. Noted: without agreement, the first question is whether international law ever allows revision of a decision that is res judicata unless special powers were expressly given. Article 83 of the 1907 Hague Convention covers revision only where reserved in the compromis (the agreement that sets the terms of an arbitration). Article 61 of the Statute of the Permanent Court does not require such special powers (1941, Part Two, I).
25. Noted: in the Jaworzina case the Permanent Court said the Conference of Ambassadors, having performed its task, kept no power to modify its decision. In the Saint Naoum case it seemed less positive about revision absent express reservation (1941, Part Two, I).
26. Noted: arbitral practice is not uniform. Umpire Lieber re-examined a case on a rehearing motion. Umpire Thornton refused rehearings in Weil, La Abra and other cases because the Convention barred it, but reconsidered Schreck. The Green case was reconsidered by the Umpire and the George Moore case by the two Commissioners. In Lazare (Haiti v. United States) Justice Strong refused a rehearing because his power was at an end once the award was filed. In the Sabotage cases Justice Roberts granted a rehearing though no provision empowered it (1941, Part Two, I).
27. Held: the 1938 decision did not give final answers to all Questions. The Tribunal did not become functus officio (having exhausted its authority). Part of its task was still pending when revision was requested, so the difficulties of asking a finished and adjourned tribunal to reconsider do not arise (1941, Part Two, I).
28. Held: the Convention does not, at this stage at least, deny the Tribunal power to grant a revision (1941, Part Two, I).
29. Held: whether revision should be granted has two parts. The first is whether the petition should be entertained. The second is whether the previous decision should be revised. The rule in Article 83 of the Hague Convention and Article 61 of the Permanent Court Statute is that these are dealt with separately (1941, Part Two, I).
30. Noted: Orinoco did not separate the two questions, but its compromis did. The Mixed Claims Commission (United States and Germany) had followed a contrary practice. Umpire Justice Roberts later said it would have been fairer to decide first the Commission's power. Germany insisted the preliminary question be decided separately, and he held it was her right (1941, Part Two, I).
31. Held: the Tribunal agreed that procedure should be followed (1941, Part Two, I).
32. Noted: the petition rests on an alleged error of law. The United States said the Tribunal wrongly read the Convention when it held investigation costs were not within damage caused by the Trail Smelter (Article III(1)). It challenged the statements about I'm Alone and about expenses of individual claimants, though it said they might be dicta. It also argued the solution was not just to all parties concerned under Article IV (1941, Part Two, I).
33. Noted: under Article 83 of the Hague Convention a revision request can be made only for discovery of a new fact. The fact must be able to influence the award decisively. It must have been unknown to the Tribunal and the party when the discussion closed (1941, Part Two, I).
34. Noted: at the first Hague Conference the United States Delegation proposed a second hearing before the same judges if a party could call new witnesses or raise new questions of law. This was seen as weakening res judicata. The text adopted was a compromise between this view and the view of de Martens and others who opposed any revision (1941, Part Two, I).
35. Noted: Article 61 of the Permanent Court Statute substantially matches Article 83. The Advisory Committee of Jurists said the right of revision affects res judicata, a point for the sake of international peace to be treated as finally settled. Justice has legitimate requirements, so revision is for cases where through no fault of the claimant essential facts stayed undisclosed or fraud was later found (1941, Part Two, I).
36. Held: neither the Hague Convention nor the Statute of the Permanent Court considers error of law a basis for revision (1941, Part Two, I).
37. Noted: in Saint Naoum the Permanent Court left open whether an award could be revised in the event of the existence of an essential error being proved or of new facts being relied on. The Tribunal read that passage as concerning error of fact, since the paragraph began by criticising a decision based on erroneous information or adopted without regard to essential facts (1941, Part Two, I).
38. Noted: rehearings or revisions are rare except where agreed. In Green, evidence before the Commissioners was not sent to the Umpire. In George Moore, a new document was produced, and the Commissioners said it was their practice to grant revision where new evidence should undoubtedly change their minds, unless there was gross laches (unreasonable delay) or probable injustice to the defendant Government (1941, Part Two, I).
39. Noted: in Schreck, Umpire Thornton granted revision at the claimant Agent's request because he had clearly erred in law. He had assumed a person born in Mexico was a Mexican national, and the Agent produced the Mexican law showing it was wrong (1941, Part Two, I).
40. Noted: in Orinoco, Venezuela said the decision was valid. The second tribunal did not disturb the Umpire's findings on the main claim, which turned on the interpretation of a contract. It said that if an arbitral decision could be challenged for erroneous appreciation, appeal and revision, which the Hague Conventions aimed to avert, would be the general rule (1941, Part Two, I).
41. Noted: the Orinoco tribunal held void for excess of power some smaller claims that had been disallowed solely on a Calvo clause ground and on non-compliance with Venezuelan law. Those grounds were irreconcilable with terms of reference requiring decision on absolute equity without regard to technical objections or local legislation (1941, Part Two, I).
42. Noted: the Sabotage cases were reopened on the allegation, later proved, that the decisions were induced by fraud. That falls within the Hague Convention and Statute limits. The passage from Justice Roberts on which the United States relies, saying a material error of law can be reopened, is therefore a dictum (1941, Part Two, I).
43. Held: Justice Roberts's statement may be justified by circumstances special to the Mixed Claims Commission. Except for correcting slips or accidental omissions, it does not state the generally accepted position in international law (1941, Part Two, I).
44. Noted: the Tribunal quoted de Neuflize v. Disconto Gesellschaft: for revision it is not enough that there was an error on a point of law or in appreciating a fact. Only lack of knowledge by the judge and one party of a material and decisive fact may give rise to revision (1941, Part Two, I, with its footnote noting that the rules of the Franco-German Mixed Arbitral Tribunals express the generally prevailing opinion).
45. Held: a mere error in law is not a sufficient ground for a revision petition (1941, Part Two, I).
46. Noted: the formula essential error came from a text voted by the Institute of International Law in 1876, and its authors were divided on its meaning. The Orinoco tribunal avoided it. In Saint Naoum the Serb-Croat-Slovene Government alleged essential error in law and fact, but the Court had in mind only possible error of fact (1941, Part Two, I).
47. Held: the proper criterion is not essential versus other errors in law, but manifest errors versus other errors in law. A manifest error is like the one in Schreck, or one a tribunal would make by overlooking a relevant treaty or relying on an agreement admittedly terminated. This is as far as precedents and practice allow (1941, Part Two, I).
48. Held: the alleged error in interpreting the Convention is not a manifest error. Further criticisms need not be considered, since even if justified they would not upset the decision. The petition must be denied (1941, Part Two, I).

1941 decision — Part Two, II (a) and (b): damage and costs after 1 October 1937

1. Noted: the United States asked the Tribunal to find damage after 1 October 1937 and award $34,807. The claim rests on the last paragraph of Part Two of the 1938 decision. This report covers the period to 1 October 1940 (1941, Part Two, II (a)).
2. Noted: the Tribunal considered the evidence from the 1937 hearings and also the Technical Consultants' reports, the United States scientist Mr. Griffin's reports of 1939 and 1940, the monthly sulphur balance sheets, all recorder data at Columbia Gardens, Waneta, Northport and Fowler's Farm, and census data (1941, Part Two, II (a)).
3. Noted: it examined each fumigation the United States alleged caused damage, and others likely to have. It considered length, intensity, frequency, time of day, humidity or drought, season, altitude and location, and survey reports (1941, Part Two, II (a)).
4. Held: the United States failed to prove that any fumigation between 1 October 1937 and 1 October 1940 caused injury to crops, trees or otherwise (1941, Part Two, II (a)).
5. Held: for expenses from 1 July 1936 to 1 October 1937, the claim cannot be allowed for the reasons already given on the earlier investigation costs. The Tribunal turned to costs since 1 October 1937 (1941, Part Two, II (b)).
6. Held: the Convention took effect on the exchange of ratifications on 3 August 1935. Under Article XIII each Government pays the expenses of presenting and conducting its case. Money spent by the United States investigating and preparing its case after the Convention entered into force were expenses of presenting the case (1941, Part Two, II (b)).
7. Why: indemnity cannot be granted without reasonable proof of injury, its cause and the damage due to it. Presenting a claim includes, by necessary implication, collecting field data and preparing it for evidence in the Article V statement of facts (1941, Part Two, II (b)).
8. Held: there is a fundamental difference between money spent mending the damageable consequences of an injury and money spent finding out its existence, cause and extent. The latter is not part of the damage, any more than counsel's fees or witnesses' travel costs. It is impossible to draw a logical line between the cost of expert reports and the cost of statements and answers under the procedure. It does not matter that different agencies of one Government incur them (1941, Part Two, II (b)).
9. Held: the Convention does not allow investigation costs under damage. Apart from Article XIII, its text and history disprove any such intention (1941, Part Two, II (b)).
10. Held: the damage to be indemnified is damage caused by the Trail Smelter in the State of Washington. The investigations were by Federal agencies, so the damage, assuming salaries could be so called, arose in the whole Union and not in one State (1941, Part Two, II (b)).
11. Held: damage appears in the preamble, Article I, Article III (twice), Article X and Article XI. It should have the same meaning throughout unless text or history shows otherwise, though in Article X its scope is limited to property by context. The preamble shows that the damage complained of is damage caused by fumes in Washington (1941, Part Two, II (b)).
12. Noted: the $350,000 in Article I was agreed with the Joint Commission's suggested indemnity in mind, as the letters of 30 January and 17 February 1934 show. The Commission's report, paragraphs 2 and 3, shows no investigation costs were included, as it recommended the fund go to persons damaged by the fumes, and said no allowance covered United States Government lands. Had the parties meant to include investigation costs in Article III they would have said so more precisely (1941, Part Two, II (b)).
13. Noted: the United States argued that this Tribunal's reference, unlike the Commission's, is not limited to property. The Tribunal noted that damage to health was asserted by interested parties then. The difference may be explained because the case was presented as a single claim for damage to national territory, not as a sum of individual claims espoused by the Government (1941, Part Two, II (b)).
14. Held: if the money is not damage under the Convention, no indemnity can be claimed for it, even if it was not properly an expense of presentation. If there were a gap, the claim would fail because it is unsupported by international practice (1941, Part Two, II (b)).
15. Noted: when a State takes up a private claim, the national's expenses in seeking local remedy before the State took up the claim may legitimately be included, as costs incidental to damage. The Tribunal knew of no case where a Government obtained an award for its own expenses of preparing proof for national or espoused claims. United States counsel knew of no precedent. The cases cited were expenses of injured nationals, all but one before the Government presented the claim (1941, Part Two, II (b), with its footnote listing those cases).
16. Held: absent settled precedent, where a tribunal is asked to award a Government's expenses of preparing proof, particularly for damage to national territory, the intent to allow it should appear from the express language or necessary implication of the instrument creating the tribunal. Neither is present (1941, Part Two, II (b)).
17. Held: even if the Tribunal could reopen the case on the expenditure from 1 January 1932 to 1 October 1937, it would have reached the same conclusion and affirmed the 1938 decision (1941, Part Two, II (b)).
18. Held: Question 1 for the period 1 October 1937 to 1 October 1940. No damage caused by the Trail Smelter in Washington occurred in that period, so no indemnity is payable (1941, Part Two, conclusion).

1941 decision — Part Three: Question 2 and the law on a State's duty

1. Held: damage has occurred since 1 January 1932 as set out in the previous decision, so the first part of Question 2 is answered in the affirmative (1941, Part Three).
2. Noted: the Joint Commission's report (I(g)) defined damage to exclude occasional damage from air pockets or unusual atmospheric conditions, for the purposes of the smelter's duty to reduce gas. Correspondence between the Governments shows this was the problem the parties mainly had in mind in drafting Question 2 (1941, Part Three).
3. Noted: Canada wished the report adopted. The United States, in its letter of 30 January 1934, would not accept limiting damage to the report's definition. It said that so long as fumigations in Washington occur with frequency, duration and intensity enough to cause injury, it has grounds of complaint regardless of the remedial works (1941, Part Three).
4. Held: the Tribunal need not decide whether to answer by United States law or international law. The United States law on air pollution (contamination of air or water) is more definite. It concerns the quasi-sovereign rights (a State's interest in the earth and air within its domain) of the States of the Union. It is in conformity with the general rules of international law. The Tribunal also considered the desire to reach a solution just to all parties (1941, Part Three).
5. Noted: Professor Eagleton wrote that a State owes at all times a duty to protect other States against injurious acts by individuals from within its jurisdiction. Many such general statements were presented. International decisions from the Alabama case onward rest on the same principle. Canada has not questioned the principle as such (1941, Part Three).
6. Held: the real difficulty is what, in each subject, counts as an injurious act (1941, Part Three).
7. Noted: the Swiss Federal Court decision between the cantons of Soleure and Argovia shows the relativity of the rule. The court enjoined use of a shooting range that endangered Soleure's territory, saying sovereignty excludes not only usurpation of sovereign rights but also actual encroachment that might prejudice the natural use of the territory. When Soleure said the improvements were insufficient, Argovia moved to resume shooting, and the court granted it. It said Soleure's demand that all endangerment be absolutely abolished apparently goes too far. Absolutely safe ranges were found only in mountain valleys, and no more precaution may be demanded near cantonal boundaries than inside a canton (1941, Part Three, citing R.O. 26 I, 450, 451 and R.O. 41 I, 137).
8. Held: no air-pollution case decided by an international tribunal has been brought to its attention, and the nearest analogy, water pollution, also has none. However, decisions of the United States Supreme Court can legitimately be a guide. It is reasonable to follow by analogy precedents on controversies between States of the Union or on their quasi-sovereign rights. This holds where no contrary rule prevails in international law. It also holds where the limits of sovereignty under the United States Constitution give no reason to reject them (1941, Part Three).
9. Noted: Missouri v. Illinois, 200 U.S. 496, 521. An injunction (a court order to stop or do something) was refused over pollution of the Illinois River. The Court said the case should be of serious magnitude, clearly and fully proved. The practice was general along the Mississippi and followed by Missouri itself. Complaints ceased as public health claims grew and purification improved. Missouri sided with Illinois when other Great Lakes riparians (owners along the water) sought to stop the Chicago sewage diversion (1941, Part Three, citing Kansas v. Colorado, 185 U.S. 125).
10. Noted: New York v. New Jersey, 256 U.S. 296, 309. An injunction was refused for lack of proof. The burden on a State is much greater than on a private complainant. The threatened invasion of rights must be of serious magnitude and established by clear and convincing evidence (1941, Part Three).
11. Held: what the Supreme Court said of its constitutional power equally applies to the extraordinary power granted this Tribunal. What is true between States of the Union is at least equally true between the United States and Canada (1941, Part Three).
12. Noted: in the case reported at 283 U.S. 473, the complainant succeeded. New York City was enjoined at New Jersey's request to stop within a reasonable time dumping sewage at sea that harmed New Jersey's coastal waters near her bathing resorts (1941, Part Three).
13. Noted: Georgia v. Tennessee Copper Company and Ducktown Sulphur, Copper and Iron Company, Limited. The suit was against private companies but dealt with cognate questions. Georgia had sought relief from Tennessee in vain. The Court called it a suit by a State for injury in its capacity of quasi-sovereign, with an interest in all the earth and air within its domain (1941, Part Three).
14. Noted: the Court (206 U.S. 230) said the State has the last word on whether its mountains are stripped of forests and its inhabitants breathe pure air. It is a fair demand of a sovereign that the air over its territory not be polluted on a great scale by sulphurous acid gas and that its forests, crops and orchards not be endangered by persons beyond its control. When the Court later framed the injunction (237 U.S. 474, 477), after an agreement on annual compensation with the Tennessee Copper Company, it went no further than a decree adequate to diminish materially the present probability of damage to Georgia's citizens (1941, Part Three).
15. Noted: science has greatly improved fume control in recent years, and this should be taken into account (1941, Part Three).
16. Held: these decisions taken as a whole are an adequate basis for one conclusion. Under the principles of international law, as well as of the law of the United States, "no State has the right to use or permit the use of its territory in such a manner as to cause injury by fumes". This covers injury in or to the territory of another State, or the properties or persons there. It applies only when the case is of serious consequence and the injury is established by clear and convincing evidence (1941, Part Three).
17. Held: the Supreme Court decisions are decisions in equity. A solution inspired by them, with the régime prescribed, will be just to all parties concerned as long as present conditions in the Columbia River Valley prevail (1941, Part Three).
18. Held: on the circumstances, Canada is responsible in international law for the conduct of the Trail Smelter (state responsibility, a State's liability for acts attributable to it). Apart from the Convention, it is Canada's duty to see that this conduct conforms to the obligation under international law as determined (1941, Part Three).
19. Held: Question 2 is answered as follows. So long as present conditions in the Columbia River Valley prevail, the Trail Smelter must refrain from causing any damage through fumes in Washington. The damage and its extent are such as would be recoverable under United States court decisions in suits between private individuals. The indemnity is to be fixed as the Governments agree under Article XI (1941, Part Three).

1941 decision — Part Four: Question 3 and the permanent régime

1. Held: since damage has occurred and may occur again without control, a régime or measure of control must apply to the smelter's operations. It stays in force until modified under Section 3, Paragraph VI of Part Four (1941, Part Four).
2. Noted: Section 1 recounts the trial period. Two Technical Consultants directed the observations. The consulting meteorologist, Dr. Patterson and then Dr. Hewson, was employed under the 1938 decision. The Consultants could require reports and give directions to the smelter, which were modified as data came in. They reported regularly, and the Tribunal met them in 1939. Canada bore the expenses (1941, Part Four, Section 1).
3. Noted: Dr. John P. Nielsen was authorised on 4 May 1938 as assistant to 1 October 1938 (1941, Part Four, Section 1).
4. Noted: the technical staff studied how meteorological conditions affect dispersal. They set up standard and new meteorological instruments and recorders in both countries, built portable instruments, and observed height, velocity, temperature and sulphur dioxide content of the air with captive balloons, pilot balloons and airplane flights. These began in May 1938 and ran through several experimental régimes in 1939 and 1940. Crops and timber were examined periodically (1941, Part Four, Section 1).
5. Noted: the details are in the Final Report Meteorological Investigations near Trail, B.C., 1938-1940 by Reginald S. Dean and Robert E. Swain, 374 pages, filed with both Governments and made part of the record. The Tribunal hoped the Governments would make this report available to scientists and smelter operators generally (1941, Part Four, Section 1).
6. Held: Section 2 sets out the findings behind the régime. Automatic recorders should be located and kept to help control emission and to give data on the effect of controls (1941, Part Four, Section 2).
7. Held: the investigations confirmed that the sulphur dioxide spreads by eddy-current diffusion. The shape of the attenuation curve with distance follows from that mechanism (1941, Part Four, Section 2).
8. Held: recorder data since May 1938 confirm the 1938 conclusion on the fall in concentration. Concentration falls very rapidly to about 16 miles downstream (6 miles from the boundary) and then more slowly. The position of the knee in the curve is somewhat affected by wind velocity, direction and other factors (1941, Part Four, Section 2).
9. Noted: Columbia Gardens, 6 miles below the smelter, is above the knee. Waneta, 10 miles below, is still in the region of very rapid decrease. Northport, 19 miles below, is well below the knee. The average ratio of Columbia Gardens to Northport concentrations was 1 to .31 in 1932 to 1935 and 1 to .39 from May 1938 to November 1940. The ratio of Columbia Gardens to Waneta was .6 and then .75, with larger individual variation (1941, Part Four, Section 2).
10. Held: the Columbia Gardens and Northport recorders give as complete a picture of attenuation as any reasonable number of recorders. Near the border the concentration will be from about .6 to .75 of that at Columbia Gardens, though in unusual cases it may be substantially equal (1941, Part Four, Section 2).
11. Noted: although the Waneta recorder could be discontinued, it was kept for a limited period of further investigation, particularly as it had been removed during one winter of the trial. Gunderson Farm, suggested by the United States, was rejected because servicing in winter would not be repaid by any appreciable advantage. Waneta is practically identical to Boundary, which United States scientists had chosen before. The Tribunal was convinced the nearby Pend-d'Oreille gorge does not harm that choice (1941, Part Four, Section 2).
12. Held: the year divides into the growing season (1 April to 30 September) and the non-growing season (1 October to 1 April). In summer the air is generally in active movement and smoke disperses rapidly. In winter calm may last several days and dispersal is slow. A similar variation occurs through the day (1941, Part Four, Section 2).
13. Noted: in the growing season there is a pronounced maximum of fumigations at about nine to ten in the morning. The smoke control office has long cut emission in the early morning hours until eight to eleven o'clock. This is a fundamental feature of the smoke control programme, and its main reason for success is that it prevents sulphur dioxide accumulating before the rising sun heats the earth's surface and brings it down. Such a fumigation reaches all valley recorders almost at once, with highest intensity near the smelter. The concentration rises quickly to a maximum in minutes and then falls exponentially. A shorter evening fumigation sometimes occurs as the sun sets (1941, Part Four, Section 2).
14. Noted: aircraft sampling shows that in calm weather the gases rise about 400 feet above the two high stacks, level out and spread horizontally. In the early morning a stratum with fairly high concentration may form over a large area. When the sun heats the surface the gas accumulated at about 2,400 feet above mean sea level descends, which explains simultaneous appearance at different distances (1941, Part Four, Section 2).
15. Noted: in the non-growing season, non-diurnal fumigation predominates. Gas drifts along the valley and takes two to eight hours to go from Trail to Northport, appearing in sequence at the recorders. Concentration at a recorder may stay steady for several days. The growing and non-growing seasons coincide almost exactly with the periods when diurnal and non-diurnal fumigations dominate, and the transition happens in September and April (1941, Part Four, Section 2).
16. Held: recorders help control in both seasons but more in the non-growing one. In a non-diurnal fumigation the gas usually reaches Columbia Gardens before Northport, so high readings there warn that more is being emitted than can be dispersed. For diurnal fumigations the only adequate protection is to prevent large accumulations, up or down stream, just before the periods when they are expected (1941, Part Four, Section 2).
17. Noted: observations over years show little likelihood of gas crossing the boundary if the wind at gas-carrying level (about 2,400 feet above mean sea level) is not in the 135 degree angle opening westward from north and is fast enough to avoid serious accumulation. The wind is measured by a cup anemometer and anemovane 300 feet above the surface on a cable between the zinc stack and a neighbouring stack, which is reliable except when the level 500 feet or more higher differs. Geostrophic wind forecasts from the Vancouver Weather Bureau are promising but not yet certain enough to use (1941, Part Four, Section 2).
18. Noted: a very significant factor is the rate of eddy-current diffusion. When low, smoke may accumulate, often up-stream with a light up-river breeze. The main factors are turbulence and lapse rate (the change of temperature with height). Standard anemometers were not precise enough for turbulence, so the Bridled Cup Indicator was designed (1941, Part Four, Section 2).
19. Noted: the turbulence criterion has limits. Marked fumigations sometimes occurred with good or excellent turbulence, when pilot balloons showed a strong down-river wind to about 2,500 feet and calm at about 4,000 feet, which acts as a blanket. The gas then moves down the valley like a giant pipe. This type is rare but can best be controlled by the Columbia Gardens recorder. In summer daytime the turbulence reading may be low while diffusion is still satisfactory, because lapse rate matters too. Measuring and applying lapse rate is not yet fully developed (1941, Part Four, Section 2).
20. Noted: other conditions matter. With high humidity, especially in rain or snow, caution is needed. With a steady barometer, conditions are unlikely to change, and fumigations occur chiefly during the transitional stages of meteorological conditions (1941, Part Four, Section 2).
21. Held: trained observers' visual observations may sometimes assess turbulence at the higher gas-carrying levels better than instruments. Where turbulence at higher levels is clearly better, the load can sometimes be safely raised. Where it is clearly worse, the smelter must, for its own advantage, reduce the load. The Tribunal used this factor to a limited extent and only in the non-growing season. The clause on alteration may allow further use if it can be done without risk of injury south of the boundary (1941, Part Four, Section 2).
22. Held: the régime should have an uninterrupted test through at least two growing periods and one non-growing period, and then be open to amendment or suspension. Paragraph VI may apply in these cases. First, if the Tribunal's expectations are not met. Second, if scientific advances allow better control. Third, if progress in reducing sulphur content makes the régime unduly burdensome for the end set by Question 2. Fourth, to suspend the régime if sulphur dioxide elimination reaches a stage where that can be done without undue risk to United States interests (1941, Part Four, Section 2).
23. Why: since the Tribunal has power to establish a régime, it must have power to alter, modify or suspend it. It would not be a solution just to all parties concerned if its action could not respond to future conditions (1941, Part Four, Section 2).
24. Noted: the investigations were probably the most thorough study ever made of an area subject to atmospheric pollution by industrial smoke. Turbulence and upper-air movement were applied to smoke control for the first time. Progress has been made in breaking up long winter fumigations. Carrying the demonstrated growing-season régime into the non-growing season with minor changes gives confidence that winter fumigations stay below the threshold of possible injury to vegetation. The growing-season régime should throttle diurnal fumigations at source so that they do not give concentrations below the boundary sufficient to injure plant life. That is the Tribunal's goal (1941, Part Four, Section 2).
25. Held: the Tribunal could not adopt the United States' suggestion of a régime under which a fixed sum is due whenever recorded concentrations exceed a set intensity for a set period, or a greater intensity for any twenty minutes. In its view and that of its scientific advisers it would unduly and unnecessarily hamper the smelter and would not be a solution fair to all parties concerned (1941, Part Four, Section 2).
26. Held: Section 3 prescribes the régime to prevent sulphur dioxide in amounts, concentration, duration and frequency capable of damaging Washington. The instruments, documents, stack height, maximum permissible emission, definitions and amendment procedure are set out in the Award section (1941, Part Four, Section 3).
27. Noted: Section 4 is a suggestion, not part of the régime. It would be to Canada's clear advantage to continue at its own expense two scientists' experimental and observational work until at least 31 December 1942, as this would give data to test the régime and find improvements (1941, Part Four, Section 4).
28. Noted: both Governments acknowledged the value of the trial period. Canada's memorandum of 28 December 1940 did not question its value despite the expense. Canada's Agent said at the 11 December 1940 hearing the Technical Consultants' research was admirable. In a colloquy of 12 December 1940 Judge Warren said the Tribunal had been ready to decide in March 1938 but thought a decision without experimentation would be unsatisfactory to both. Mr. Tilley agreed it was in the parties' interests (1941, Part Four, Section 4).
29. Noted: the United States memorandum of 7 January (the year is misprinted in the source) said it did not minimise the Consultants' meritorious work. Mr. Raftis said on 9 December that the studies were most helpful, as before the Tribunal could only conjecture what happened to the gas. Mr. Griffin's report of 30 November 1940 said the Canadian meteorologists added much fundamental knowledge, and that published results would interest smelter managers handling sulphur dioxide. He noted it remained to be determined whether three years of experiment could bring about a permanent end to harmful fumigations south of the boundary (1941, Part Four, Section 4).

1941 decision — Parts Five and Six, and the Annex: Question 4, investigation rights and clarification

1. Held: the prescribed régime will probably remove the causes of the controversy and probably prevent any material damage in Washington in future. As it may not do so, and Question 2 requires the smelter to refrain from damage, Question 4 is answered as set out in the Award section (1941, Part Five).
2. Held: indemnity for damage defined under Question 2 is payable only when and if the Governments arrange the disposal of claims under Article XI. The reasonable cost of United States agents' investigations, up to $7,500 a year, is compensation on account of the answers to Questions 2 and 3, and not indemnity for damage. It is payable only if the Governments determine that damage occurred due to the smelter and have disposed of claims, and never beyond the indemnity for damage (1941, Part Five).
3. Held: because further investigation may be possible, the Tribunal had to include a provision. Investigators of either Government and members of the Commission under Paragraph VI may at reasonable times inspect the smelter's operations and enter properties in Washington claimed to be affected. This includes localities where instruments are operated. Where instruments must be kept on United States territory, the United States Government undertakes to secure the facilities reasonably required. The Tribunal strongly hoped any future investigations would be conducted jointly (1941, Part Six).
4. Noted: by letter of 6 May 1941 the three members declared that the Technical Consultants' letter of 28 April 1941 states the correct interpretation of clause IV, Section 3 of Part Four. The Consultants explained that a strict reading of the tables might force a complete shutdown, though the rules were meant for the Dwight and Lloyd roasting operations. Small amounts escaping from the blast furnace and other operations are insignificant and were never specified in any régime. Tail gases are a normal part of smelting. They proposed to read the clause as the maximum hourly permissible emission of untreated sulphur dioxide from the roasting plants (1941, Annex I and II).

Authorities

• Story Parchment Company v. Paterson Parchment Paper Company (1931), 282 U.S. 555 — applied. Damages may rest on just and reasonable inference where exact proof is impossible (1938, Part Two).
• Allison v. Chandler, 11 Michigan 542 — cited with approval. Denying damages for want of certainty is the certainty of injustice (1938, Part Two).
• Anderson v. American Smelting and Refining Co., 265 Federal Reporter 928 (1919), Judge Johnson — quoted on the weight of opinion evidence from expert witnesses (1938, Part Two).
• Ralston v. United Verde Copper Co., 37 Federal Reporter 2d, 180, and 46 Federal Reporter 2d, 1 — relied on for the measure of damage for crop land: reduction in the value of use (1938, Part Two, clause 1).
• Baltimore and Potomac R.R. v. Fifth Baptist Church (1883), 108 U.S. 317 — cited for special damage from location (1938, Part Two, clause 1).
• Sedgwick on Damages, 9th ed. 1920, Sections 932, 947 and 937a — relied on for the measure of damage for permanent soil injury and for destroyed timber (1938, Part Two, clauses 1 and 2(B)(a)).
• Sterrett v. Northport Smelting and Refining Co. (1902), 30 Washington Reports 164; Rowe v. Northport Smelting and Refining Co. (1904), 35 Washington Reports 101; Park v. Northport Smelting and Refining Co. (1907), 47 Washington Reports 597; Johnson v. Northport Smelting and Refining Co. (1908), 50 Washington Reports 507 — noted as earlier Washington suits on fumigation claims, not cited by counsel (1938, Part Two, clause 2(B)).
• Judgment No. 13, Permanent Court of International Justice, Series A, No. 17, pages 27 and 28 (Chorzow Factory) — cited that individuals' damage may serve as a scale for the reparation due to the State (1938, introduction; 1941, introduction). Pages 31, 32, 75 and 76 are cited on res judicata (1941, Part Two, I).
• I'm Alone award of 5 January 1935 (Convention of 23 January 1934) — distinguished. The facts here were not of the type justifying damages for violation of sovereignty (1938, Part Two, clause 7; 1941, Part Two, I).
• Dr. James Brown Scott, Hague Court Reports, page XXI — quoted that international law is the law of an international tribunal absent contrary agreement (1941, Part Two, I).
• Pious Funds of California (14 October 1902, Hague Court Reports 1916, p. 3) — followed. Res judicata applied to the earlier Thornton award (1941, Part Two, I).
• Fabiani case (French-Venezuelan Claims Commission, Ralston's Report, Umpire Plumley, p. 110) — followed on finality of an award and as to a decision not denying jurisdiction (1941, Part Two, I).
• Orinoco Steamship Company case (25 October 1910) — followed on the importance of res judicata; also analysed on excess of power and refusal to revise for mere error (1941, Part Two, I).
• Permanent Court of International Justice Advisory Opinions, Series B: No. 8 (Jaworzina), No. 9 (Monastery of Saint Naoum) and No. 11 (Polish Postal Service in Danzig) — cited for res judicata and on revision (1941, Part Two, I).
• Société Commerciale de Belgique (Belgium v. Greece), Series A/B, No. 78, p. 174 — cited that awards final and without appeal cannot be confirmed or annulled by the Court (1941, Part Two, I).
• Frelinghuysen v. Key, 110 U.S. 63, 71, 72 — cited that awards of the United States-Mexican Claims Commission are final and conclusive (1941, Part Two, I).
• Chorzow Factory, Judgment No. 11, Series A, No. 13, with Judge Anzilotti's dissent (pp. 23, 26, 27), and Judgment No. 7, and Judge Ehrlich's dissent in Judgment No. 13 — discussed on res judicata of incidental decisions (1941, Part Two, I).
• Tiedemann v. Poland, Recueil des Décisions des Tribunaux Arbitraux Mixtes, Tome VII (1928), p. 702 — cited for the view that a decision only on jurisdiction may be reversed (1941, Part Two, I).
• Hague Convention for the Pacific Settlement of Disputes (18 October 1907), Article 83; Statute of the Permanent Court of International Justice, Articles 59 and 61 — applied on revision and on the binding effect of decisions (1941, Part Two, I).
• Moore, International Arbitrations: United States-Mexican Mixed Claims Commission cases Weil, La Abra, Schreck, A. A. Green and George Moore (pp. 1329, 1357, 1358); Lazare (Haiti v. United States), p. 1793 — discussed on rehearings and revision (1941, Part Two, I).
• Sabotage cases, American-German Mixed Claims Commission, Umpire Justice Roberts (decision of 15 December 1933; American Journal of International Law, 1940, pp. 154, 157-158, 164) — distinguished; the dictum on material error of law was not accepted as general law (1941, Part Two, I).
• de Neuflize v. Disconto Gesellschaft, Recueil des Décisions des Tribunaux Arbitraux Mixtes, t. VII, 1928, 629 — followed that error of law or appreciation of fact is not enough for revision (1941, Part Two, I).
• D. V. Sandifer, Evidence before International Tribunals, 1939, p. 299 — compared on the power to grant revision (1941, Part Two, I).
• Eagleton, Responsibility of States in International Law (1928), p. 80 — quoted on a State's duty to protect other States from injurious acts by individuals (1941, Part Three).
• The Alabama case — noted as based on the same general principle (1941, Part Three).
• Swiss Federal Court, Soleure v. Argovia (R.O. 26 I, 450, 451; R.O. 41 I, 137; D. Schindler, American Journal of International Law, Vol. 15 (1921), pp. 172-174) — used to show the relativity of the rule on injurious acts (1941, Part Three).
• Missouri v. Illinois, 200 U.S. 496, 521, and Kansas v. Colorado, 185 U.S. 125 — followed by analogy on the high standard of proof between States (1941, Part Three).
• New York v. New Jersey, 256 U.S. 296, 309 — followed on the need for clear and convincing evidence (1941, Part Three).
• The case at 283 U.S. 473 (New Jersey against the City of New York) — noted as a successful complaint of water pollution (1941, Part Three).
• Georgia v. Tennessee Copper Company and Ducktown Sulphur, Copper and Iron Company, Limited, 206 U.S. 230 and 237 U.S. 474, 477 — the leading air pollution decisions, relied on for the Tribunal's conclusion (1941, Part Three).
• Also cited in footnotes: Life of Douglas Fir Seed in the Forest Floor by Leo A. Isaac, Journal of Forestry, Vol. 23 (1935); The Pine Trees in the Rocky Mountain Region by G. B. Sudworth, USDA Bulletin (1917); Timber Growing and Logging Practice in the Douglas Fir Region by T. T. Munger and W. B. Greely, USDA Technical Bulletin (1927); Western Yellow Pine in Oregon by T. T. Munger, USDA Technical Bulletin (1917); Applied Silviculture in the United States by R. H. Westveld (1935); the rules of procedure of the Franco-German Mixed Arbitral Tribunals; and these cases on a Government's expenses: Santa Clara Estates Company (British Venezuelan Commission of 1903), Orinoco Steamship Company v. Venezuela (Ralston's Report p. 107), United States-Venezuelan Arbitration at The Hague (1909), Compagnie Générale des Asphaltes de France, H. J. Randolph Hemming, Shufeldt (United States v. Guatemala), Mather and Glover v. Mexico, Patrick H. Cootey v. Mexico, The Louisa, Dr. John Baldwin v. Mexico, Robert H. May v. Guatemala and Salvador Commercial Company v. Guatemala.

Award

The Tribunal made two awards. Each direction below cites the decision and Part that contains it.

1938 decision (16 April 1938)

1. Question 1 (to 1 October 1937): damage caused by the Trail Smelter in Washington occurred from 1 January 1932 to 1 October 1937. The indemnity is $78,000, as complete and final indemnity for all damage in those dates (1938, Part Two, conclusion).
2. Interest at six per cent a year runs on the $78,000 from the date of filing the report until payment. The Tribunal cannot alter this decision later (1938, Part Two, conclusion).
3. The $78,000 is made up of $62,000 for cleared land and uncleared land other than timber, and $16,000 for uncleared land used for timber (1938, Part Two, clause 2).
4. All other heads of claim were disallowed. They were livestock, Northport town property, business enterprises, slag and water, violation of sovereignty with investigation costs, and interest on $350,000 (1938, Part Two, clauses 3 to 8).
5. Damage after 1 October 1937, and the indemnity for it, was left to the final decision (1938, Part Two, conclusion).
6. Question 2 (temporary): until the final decision, the Trail Smelter must refrain from causing damage in Washington to the extent set in Part Four until 1 October 1940. Afterwards it must do so to the extent the final decision requires (1938, Part Three).
7. Question 3 (temporary régime), clause 1: the Tribunal appoints two Technical Consultants, Reginald S. Dean and Robert E. Swain, with successors named by the Tribunal. They stop acting as Advisers under the Convention during the trial period (1938, Part Four, clause 1).
8. Clause 2: before 1 May 1938 the Trail Smelter must employ a trained consulting meteorologist, subject to the Technical Consultants' approval. From 1 May 1938 the observations the Consultants consider necessary are made under their direction. They determine, by captive balloons and otherwise, the weather conditions and the height, velocity, temperature and other features of the gas-carrying air currents and stack emissions (1938, Part Four, clause 2).
9. Clause 3: from 1 May 1938 the Trail Smelter must install, operate and maintain the observation stations, the stack equipment and the sulphur dioxide recorders that the Consultants consider necessary. Not more than three recorders may be stationary. The Consultants direct their location in both countries and can require regular reports on the plant's methods of operation (1938, Part Four, clause 3(a) to (e)).
10. The Trail Smelter must run its operations as the Consultants and the Tribunal direct, based on the data obtained. They may change their instructions at any time. The Tribunal intends the administration to be as flexible as possible (1938, Part Four, clause 3(e) and (f)).
11. Clause 4: the Consultants report to the Tribunal at the dates and in the manner it prescribes (1938, Part Four, clause 4).
12. Clause 5: the observations and operations run on a trial basis through the rest of the 1938 growing season, the 1939 and 1940 growing seasons, the winters of 1938-1939 and 1939-1940, and until 1 October 1940. The Tribunal may end the trial earlier (1938, Part Four, clause 5).
13. Clause 6: at the end of the trial the Tribunal will give a final decision on a permanent régime and any indemnity. The report is due within three months of the trial's end (1938, Part Four, clause 6).
14. Clause 7: the Tribunal must meet at least once in 1939. Clause 8: if the Consultants disagree, the Tribunal decides, and all persons and the Trail Smelter must act on that decision (1938, Part Four, clauses 7 and 8).
15. Clause 9: from 1 May to 1 October 1938 the smelter's sulphur emission is limited. From 25 April to 10 May and from 22 June to 6 July, not more than 100 tons a day of sulphur may be emitted from the stacks (1938, Part Four, clause 9(a)).
16. For the whole period to 1 October 1938 the sulphur dioxide recorders at Columbia Gardens and at the Stroh farm (or another approved point) must run continuously, with relative humidity observations at both (1938, Part Four, clause 9(b)).
17. If between sunrise and sunset the concentration at Columbia Gardens exceeds one part per million for three consecutive 20-minute periods and humidity is 60 per cent or higher, the smelter is told at once. Emission is then held at 5 tons of sulphur an hour or less until the concentration falls to 0.5 part per million (1938, Part Four, clause 9(b)).
18. The Consultants or the Tribunal may suspend this regulation temporarily if it interferes with an investigation in progress (1938, Part Four, clause 9(c)).
19. Clause 10: Canada must pay the expenses of the temporary régime. The Tribunal fixes the pay of the Consultants and assistants. The Consultants render accounts, approved in writing by the Chairman. Canada deposits the necessary sums with a financial institution named by the Chairman. The Tribunal reports to Canada on sums received and spent, and refunds any unspent amount at the end of the trial (1938, Part Four, clause 10).
20. Clause 11: Tribunal and Chairman mean the Tribunal and Chairman as constituted at any future time. Trail Smelter means the Consolidated Mining and Smelting Company of Canada, Limited, or its successors and assigns (1938, Part Four, clause 11).
21. Canada remains bound by any existing Convention obligation about indemnity for damage between 1 October 1937 and 1 October 1940, or an earlier date of the final decision (1938, Part Four, end).

1941 decision (11 March 1941)

1. Request to revise the 1938 decision: the petition is denied (1941, Part Two, I).
2. Question 1 for 1 October 1937 to 1 October 1940: no damage caused by the Trail Smelter in Washington occurred, so no indemnity is to be paid (1941, Part Two, conclusion).
3. The United States claims for investigation costs from 1 July 1936 to 1 September 1940, $38,657.79 with interest, are not allowed (1941, Part Two, II (b)).
4. Question 2: so long as present conditions in the Columbia River Valley prevail, the Trail Smelter must refrain from causing any damage through fumes in Washington. The damage and its extent are such as would be recoverable in United States court suits between private individuals. The indemnity is fixed as the Governments agree under Article XI (1941, Part Three).
5. Question 3: the Tribunal prescribes a permanent régime of control. It stays in force until modified under Section 3, Paragraph VI (1941, Part Four).
6. Instruments: wind direction and velocity by standard continuous-record instruments, read and transcribed at least hourly for the Smoke Control Office. Turbulence by the Bridled Cup Turbulence Indicator. Both instruments stay at the present site near the zinc stack or another site not less favourable. Temperature and barometric pressure by standard instruments (1941, Part Four, Section 3, I A).
7. The Bridled Cup instrument is a light horizontal wheel with twenty-two curved aluminium cups, on a bridled shaft whose angle of rotation is proportional to the square of the wind velocity. One full revolution corresponds to 36 miles an hour. One make and break of eighteen contact points equals a change of two miles an hour (1941, Part Four, Section 3, I A(b)).
8. Sulphur dioxide is measured by standard automatic recorders. One is at Columbia Gardens, with automatic transmission of its record to the Smoke Control Office. A second is kept near Northport. A third is kept near Waneta and may be discontinued after 31 December 1942 (1941, Part Four, Section 3, I B).
9. Documents: recorder readings are tabulated and kept on file at the smelter. The original meteorological recordings are preserved. A monthly summary of daily sulphur balances is sent to both Governments (1941, Part Four, Section 3, II).
10. Stacks: sulphur dioxide must be discharged from stacks no lower than the present ones. After a long shutdown cools the stacks, gases containing sulphur dioxide must not be emitted until hot gases free of sulphur dioxide have heated them to normal temperature (1941, Part Four, Section 3, III).
11. Maximum permissible emission: two tables, for the growing season and the non-growing season, fix the maximum hourly emission in tons of contained sulphur. They vary by turbulence (bad, fair, good, excellent), by wind (favourable or not) and by time of day. The five time bands are midnight to 3 a.m.; 3 a.m. to 3 hours after sunrise; 3 hours after sunrise to 3 hours before sunset; 3 hours before sunset to sunset; and sunset to midnight. The figures in the tables are not legible in the source text, so they are not reproduced here (1941, Part Four, Section 3, IV).
12. General restriction (a), growing season: if the Columbia Gardens recorder shows 0.3 part per million or more for two consecutive 20-minute periods and the wind is not favourable, emission is cut by four tons of sulphur an hour. It is stopped completely when turbulence is bad. This lasts until the recorder shows 0.2 or less for three consecutive periods (1941, Part Four, Section 3, IV (a)).
13. General restriction (a), non-growing season: the trigger is 0.5 part per million for three consecutive 20-minute periods, with the same cut and the same release test (1941, Part Four, Section 3, IV (a)).
14. (b) In rain or snow emission is cut by two tons an hour, from when precipitation can be seen from the smelter until twenty minutes after it stops. (c) If the slag retreatment furnace is not operating, emission is cut by two tons an hour (1941, Part Four, Section 3, IV (b) and (c)).
15. (d) If instruments show fair, good or excellent turbulence but trained observers clearly see poor diffusion, emission falls to the column (1) figure if the wind is not favourable, or column (2) if it is favourable. (e) When several restrictions apply together, the largest reduction applies (1941, Part Four, Section 3, IV (d) and (e)).
16. (f) In the non-growing season, if the instruments show fair turbulence and unfavourable wind but trained observers clearly see excellent diffusion, emission may rise to the column (5) figure. Restrictions (a), (b), (c) and (e) still apply. Each use of this provision must be fully recorded and the record sent to both Governments within one month (1941, Part Four, Section 3, IV (f)).
17. (g) Nothing relieves the smelter from reducing emission below the table figures as prudent plant operation requires (1941, Part Four, Section 3, IV (g)).
18. Definitions: a wind is favourable if it comes from any direction outside the 135 degree angle opening westward from north. It must blow at five miles an hour or more and persist for thirty minutes at the point of observation. All other winds are not favourable (1941, Part Four, Section 3, V (a)).
19. Turbulence in half-hour Bridled Cup readings is bad at 0 to 74, fair at 75 to 149, good at 150 to 349 and excellent at 350 and above. If the Governments agree on a better instrument, its scale is calibrated against the Bridled Cup (1941, Part Four, Section 3, V (b)).
20. Amendment or suspension: after 31 December 1942, if either Government asks for amendment or suspension and the other declines, each appoints a scientist of repute within one month. The two form a Commission. If they do not agree within three months, they jointly appoint a third scientist as Chairman. The majority decides, or the Chairman if there is no majority, within one month (1941, Part Four, Section 3, VI).
21. If the two scientists cannot agree on the third, the President of the American Chemical Society appoints him within one month of the failure. The Governments may extend any of the time periods by agreement (1941, Part Four, Section 3, VI).
22. The Commission may grant or refuse the request, wholly or partly, as it thinks appropriate to prevent damage in Washington. Its decision is final, and the Governments must take the action needed to conform, under Article XII (1941, Part Four, Section 3, VI).
23. The scientists' pay and reasonable expenses are paid by the requesting Government, or shared equally if both request. If, on the United States' request, the Commission finds damage occurred through fumes in Washington despite compliance with the régime, Canada pays them (1941, Part Four, Section 3, VI).
24. Section 4 is a suggestion, not a direction. The Tribunal strongly thought it advantageous for Canada to continue, at its own expense, two scientists' observational work until at least 31 December 1942 (1941, Part Four, Section 4).
25. Question 4 (a): if damage as defined under Question 2 has occurred since 1 October 1940 or occurs in future, an indemnity is paid. This applies whether it comes from failure to comply or despite the régime. It is paid only when and if the two Governments arrange the disposal of claims under Article XI (1941, Part Five).
26. Question 4 (b): if the United States must keep an agent in the area to see whether damage occurs despite the régime, the reasonable cost of the investigations is paid to the United States as compensation. The limit is $7,500 in any one year (1941, Part Five).
27. That compensation is payable only if and when the Governments determine under Article XI that damage occurred that year from the smelter and have disposed of claims. It is never payable beyond the indemnity for damage. It is compensation on the answers to Questions 2 and 3 and not part of the indemnity for damage (1941, Part Five).
28. Investigators of either Government, and Commission members under Paragraph VI, may at reasonable times inspect the smelter's operations and enter properties in Washington claimed to be affected by fumes. This also applies to localities where instruments operate (1941, Part Six).
29. Where instruments must be kept on United States territory, the United States Government must secure the facilities reasonably required for Canada (1941, Part Six).
30. The Tribunal expressed the strong hope that future investigations would be conducted jointly (1941, Part Six).
31. Annex: by letter of 6 May 1941 the Tribunal declared that the Technical Consultants' statement is the correct interpretation of clause IV, Section 3 of Part Four. The tables and restrictions give the maximum hourly emission of untreated sulphur dioxide from the roasting plants, in tons of contained sulphur (1941, Annex I and II).
32. Costs: under Article XIII of the Convention each Government bears the expenses of presenting its case and of its national member and scientist. Shared expenses, including the neutral member's honorarium, are borne in equal shares. The award makes no other costs order (Convention, Article XIII).

Legal Principle / Ratio

The Tribunal held that under international law, and under United States law, a State may not use or permit the use of its territory to cause serious fume injury in the territory of another State. The injury must be shown by clear and convincing evidence. Canada was responsible for the Trail Smelter's conduct. The Tribunal then fixed a continuing régime of control instead of closing the smelter.

• Key holding: "no State has the right to use or permit the use of its territory in such a manner as to cause injury by fumes" (1941, Part Three).
• The holding applies only when the case is of serious consequence and the injury is "established by clear and convincing evidence" (1941, Part Three).
• A final decision of an international tribunal is res judicata. A mere error in law is not a ground for revision. A manifest error might be (1941, Part Two, I).
• Obiter: on whether the facts violated United States sovereignty apart from the Convention, the Tribunal found it unnecessary to decide (1938, Part Two, clause 7). It also declined to rule on whether slag and water fall within damage caused by the Trail Smelter (1938, Part Two, clause 6).
• A Government's own costs of investigating and preparing proof are not damage under the Convention and are not recoverable (1941, Part Two, II (b)).

Critical Analysis

Analysis based on the judgment text.

• The Tribunal said that no international decision on air or water pollution was known to it. It reached the principle by analogy from United States Supreme Court cases, which it treated as equity decisions (1941, Part Three).
• The principle is tied to conditions. The Tribunal said its solution would be just as long, at least, as the present conditions in the Columbia River Valley continue to prevail. The award does not say what happens if conditions change, apart from the amendment machinery (1941, Part Three; Part Four, Section 3, VI).
• The Tribunal admitted limits in its own evidence. Experiments were too few, field observations were not simultaneous, and soil and water tests were too limited. It still awarded damages on a just and reasonable inference (1938, Part Two).
• The régime tables were open to a reading that nobody intended. After the decision, the Technical Consultants had to say that a strict reading could force a complete shutdown, and that only untreated roasting-plant gas was meant (1941, Annex II).
• The $78,000 award came against a claim of $2,100,011.17. Most heads of claim failed for lack of proof, or because they were too remote, or because they were not damage under the Convention (1938, Part Two; 1941, introduction).

Significance

• The award is the Tribunal's own answer on a State's duty. It says no State may use or permit the use of its territory to cause serious fume injury in another State's territory (1941, Part Three).
• It holds the State, not only the company, responsible. Canada was responsible in international law for the Trail Smelter's conduct (1941, Part Three).
• It shows a remedy that keeps the plant running. A permanent régime of limits, with recorders and amendment machinery, replaced closure (1941, Part Four).
• It uses scientific study as the basis of the régime. The Tribunal called the three-year investigation probably the most thorough study ever made of an area subject to atmospheric pollution by industrial smoke (1941, Part Four, Section 2).
• It affirms that final international decisions are res judicata and that error of law alone does not allow revision (1941, Part Two, I).
• It applied the test of clear and convincing evidence between States, and borrowed United States rules of damage for the sums due (1938, Part Two; 1941, Part Three).

Exam-Important Points

• Facts: fumes from the Trail Smelter, British Columbia, damaged Washington State. The Convention of 15 April 1935 sent four Questions to a three-member Tribunal.
• Principle: no State has the right to use or permit the use of its territory to cause injury by fumes. It needs serious consequence and clear and convincing evidence (1941, Part Three).
• Awards: $78,000 for 1 January 1932 to 1 October 1937 (1938). No damage and no indemnity for 1 October 1937 to 1 October 1940 (1941).
• Régime: a temporary régime and Technical Consultants in 1938. A permanent régime in 1941, based on recorders, turbulence and wind conditions, open to amendment after 31 December 1942.
• Trap 1: the Tribunal did not award investigation costs or violation of sovereignty damages. Costs are not damage under the Convention (1938, Part Two, clause 7; 1941, Part Two, II (b)).
• Trap 2: the 1938 decision on Question 1 was final and res judicata. The 1941 petition to revise it for error of law was denied (1941, Part Two, I).
• Trap 3: Article IV applies United States law and practice in dealing with cognate questions as well as international law. It does not exclude international law (1941, Part Two, I).
• Trap 4: the principle is not a ban on every emission. The injury must be of serious consequence and clearly proved (1941, Part Three).

Prepared from the full text of the judgment. The award has no numbered paragraphs, so references are to the 1938 or 1941 decision and its Part.