Trail Smelter, and the Rule It Made
Chapter Fifteen
Syllabus topic 1, "Environmental Federalism and International Order"
Pages 45 to 47 of 663
In one line
A Canadian smelter's fumes damaged American farms, and the tribunal that decided the case in 1941 wrote the sentence on which the whole of international environmental law is built.
In exam wording: the Trail Smelter arbitration established that, under the principles of international law, no State has the right to use or permit the use of its territory in such a manner as to cause injury by fumes in or to the territory of another or the properties or persons therein, when the case is of serious consequence and the injury is established by clear and convincing evidence.
Why the law needed this case
Before 1941 there was no rule at all about transboundary pollution. There were rules about war, about diplomats, about treaties and about territory. There was nothing that said one State may not poison another's fields. The tribunal had to build the rule, and it did so from the decisions of the Supreme Court of the United States in disputes between States of the American union, because those were the only decisions in the world about a comparable problem.
The case
Facts. Trail Smelter (United States v. Canada), 3 RIAA 1905, awards of 16 April 1938 and 11 March 1941. A lead and zinc smelter at Trail in British Columbia, about seven miles north of the international boundary, discharged very large quantities of sulphur dioxide. The fumes travelled down the Columbia River valley into the State of Washington and damaged crops and forest trees. The two governments referred the dispute to a tribunal of three under a convention of 15 April 1935, asking four questions: whether damage had occurred since 1932 and what indemnity should be paid; whether the smelter should be required to refrain from causing damage in future; what regime or measures it should adopt; and what indemnity should be paid for any such regime.
Held. The Tribunal awarded the United States seventy-eight thousand dollars for damage caused between 1932 and 1937 and imposed a detailed permanent operating regime on the smelter, limiting emissions by season and by wind condition and requiring continuous monitoring. Its statement of the law is the passage every student must be able to quote or paraphrase exactly: 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 in or to the territory of another or the properties or persons therein, when the case is of serious consequence and the injury is established by clear and convincing evidence.
Why it matters here. It is the origin of Stockholm Principle 21 and Rio Principle 2, of the customary principle of prevention, and of every argument in Module IV about transboundary hazards. MU has set it as a short note on two of the seven printed papers.
Trail Smelter, and the Rule It Made
Broken down: the four limbs of the rule
- No State has the right to use or permit the use of its territory. Note "or permit". The smelter was privately owned. The rule reaches what a State allows on its territory, not only what it does. That is what makes it useful against private polluters.
- In such a manner as to cause injury in or to the territory of another. The harm must cross a border. Purely domestic pollution is outside the rule.
- When the case is of serious consequence. There is a threshold. Trivial harm is not enough. The modern formulation is "significant harm".
- And the injury is established by clear and convincing evidence. A demanding standard of proof, and the limb students most often forget. It is the reason so few transboundary claims succeed.
Worked example
A copper plant in State A, forty kilometres from the border, emits sulphur dioxide. Farmers in State B claim their orchards are failing. Apply the four limbs.
- Territory and permission. The plant is private. It does not matter: State A permits its operation.
- Crossing the border. Prevailing winds carry the plume into State B. Satisfied.
- Serious consequence. State B must show real loss, not a nuisance. Reduced yield across a measurable area will do; a smell will not.
- Clear and convincing evidence. This is where the claim will be won or lost. State B must exclude other causes: disease, drought, its own domestic emissions. Trail Smelter itself took three years of scientific work and a specially built network of recording stations.
Distinctions
| Trail Smelter | Corfu Channel | |
|---|---|---|
| Year | 1938 and 1941 | 1949 |
| Forum | Arbitral tribunal | International Court of Justice |
| Subject | Fumes from a smelter | Mines in a strait |
| Formulation | No State may use or permit the use of its territory to cause injury by fumes | Every State's obligation not to allow knowingly its territory to be used for acts contrary to the rights of other States |
| Effect | The environmental rule | The general rule, and the one the Court later called the origin of prevention |
What it does NOT mean
It is not a rule of strict liability. The Tribunal did not say a State is liable for all transboundary harm. The threshold and the standard of proof are limits inside the rule itself.
It was not a treaty case. The Tribunal was applying general international law, which is why the case is cited as evidence of custom rather than of a treaty obligation.
It did not shut the smelter. It regulated it. The regime the Tribunal imposed let the smelter carry on operating within limits, which is the shape most environmental remedies have taken ever since.
Trail Smelter, and the Rule It Made
Quick revision
- Trail Smelter (United States v. Canada), 3 RIAA 1905, awards of 1938 and 1941.
- Sulphur dioxide from a smelter in British Columbia damaged crops in Washington.
- Four limbs: territory or permission, harm crossing the border, serious consequence, clear and convincing evidence.
- Damages awarded and a permanent operating regime imposed.
- The source of Stockholm Principle 21, Rio Principle 2 and the customary principle of prevention.
Test yourself
1. State the Trail Smelter rule and identify its two limits. No State has the right to use or permit the use of its territory so as to cause injury by fumes in or to the territory of another, when the case is of serious consequence and the injury is established by clear and convincing evidence. The two limits are the seriousness threshold and the standard of proof.
2. Why does the word "permit" matter? Because the polluter was a private company. The rule reaches what a State allows on its territory, which is what makes it usable against private industry.
3. Did the Tribunal close the smelter? No. It awarded damages and imposed a permanent operating regime, which is the pattern environmental remedies have followed since.
The rest of this subject
These notes are cut from the University's printed syllabus. Open the syllabus itself, or the past papers, for the same subject.