Introduction to Climate Change

3. Customary International Law and Transboundary Air Pollution

The Trail Smelter dispute is perhaps the most famous international environmental dispute. It involved transboundary SO2 emissions emanating from a smelter located in British Columbia just a few miles north of the U.S. Canada border. The facts of the case were presented by the Arbitral panel's 1941 final decision.

In 1896, a smelter was started under American auspices near the locality known as Trail, B.C. In 1906, the Consolidated Mining and Smelting Company of Canada, Limited, obtained a charter of incorporation from the Canadian authorities, and that company acquired the smelter plant at Trail as it then existed. Since that time, the Canadian company, without interruption, has operated the Smelter, and from time to time has greatly added to the plant until it has become one of the best and largest equipped smelting plants on the American continent. In 1925 and 1927, two stacks of the plant were erected to 409 feet in height and the Smelter greatly increased its daily smelting of zinc and lead ores. This increased production resulted in more sulphur dioxide fumes and higher concentrations being emitted into the air. In 1916, about 5,000 tons of sulphur per month were emitted; in 1924, about 4,700 tons; in 1926, about 9,000 tons-an amount which rose near to 10,000 tons per month in 1930. In other words, about 300-350 tons of sulphur were being emitted daily in 1930. (It is to be noted that one ton of sulphur is substantially the equivalent of two tons of sulphur dioxide or SO2.)

This plume of sulfur dioxide traveled across the U.S-Canada border and damaged the property of apple growers in Washington state. For a variety of reasons (discussed below), the Washington State residents could not bring a lawsuit either in Washington State or in British Colombia, so they asked the U.S. government to intervene on their behalf in 1927. This started a long and involved process that would take thirteen years.