A U.S. District Court in Washington has held that Indian tribes are exempt from CERCLA liability. This is the latest decision in the Pakootas v. Teck Cominco Metals, Ltd. case that began in 2005 when members of Washington State's Colville Tribe sued the Canadian operators of the world's largest lead-zinc smelter after discovering that discharges of hazardous waste from the smelter had been carried downstream by the Columbia River and deposited on tribal lands in the U.S. In their amended answer, Teck asserted a CERCLA counterclaim against the Pakootas that the tribe moved to dismiss because they were "not person[s] subject to liability under CERCLA." The court agreed, holding that Indian tribes were not expressly listed as a "person" and was separately defined elsewhere in CERCLA. Moreover, the court actually stated that it is not an "absurd" result that persons can be liable to Indian tribes under CERCLA but Indian tribes can never be liable under CERCLA themselves unless Congress expressly waives their "immunity from suit." This ruling removes an important enforcement mechanism from parties seeking to recover cleanup costs at polluted sites owned or operated by Indian tribes.