The Trail Smelter dispute was a trans-boundary pollution case involving the federal governments of both Canada and the United States, which eventually contributed to establishing the harm principle in the environmental law of transboundary pollution.

The Teck Cominco smelter, also known as the Teck Cominco Lead-Zinc Smelter, Cominco Smelter, and Trail smelter located in Trail, British Columbia, Canada, is the largest integrated lead-zinc smelter of its kind in the world. It is situated approximately 10 miles (16 km) north of the border between British Columbia, Canada and Washington, in the United States, on the Columbia River. It is owned and operated by Vancouver, British Columbia-based Teck Cominco Metals Ltd—renamed Teck Resources.