On January 24, 2000, WLF filed a brief urging the court to reverse a district court ruling that upheld the EPA arbitrary 1980 measure of dioxin’s cancer potency factor. In its brief on appeal, WLF argued that EPA’s dioxin policy constitutes a rule that should have been subject to notice and comment rulemaking procedures under the Administrative Procedure Act. WLF’s brief also demonstrated that the EPA ignored studies by its own Science Advisory Board and other experts clearly showing that certain levels of dioxin were not harmful. On April 11, 2001, WLF scored a major victory for itself and WLF’s clients when the United States Court of Appeals for the Eighth Circuit vacated a $100 million Superfund liability ruling by the U.S. District Court for the Eastern District of Arkansas, and remanded the case to the district court to determine whether the Hercules company is liable, and if so, to what extent, for the costly cleanup of an industrial site containing dioxins.