The EPA revised its emissions standards for hexavalent chromium released into the air by chrome plating operations. The revised standards, however, do not comply with requirements of the Clean Air Act that standards for toxic air emissions must provide for the maximum achievable reduction of emissions, also known as “Maximum Achievable Control Technology,” or “MACT.” The standard was challenged in the U.S. Court of Appeals for the District of Columbia Circuit by both industry, which claims it is too stringent, and environmental organizations, which claim that its failure to comply with the MACT requirement violates the plain language of the Act. Public Citizen filed an amicus brief on behalf of Rep. Henry Waxman, one of the principal authors of the Clean Air Act Amendments that impose the MACT requirement, supporting the environmental groups. The brief explained that the statutory language and the structure and purpose of the statute limit EPA’s discretion in setting standards and require that standards issued by EPA achieve at least the floor protections provided by the MACT requirement as defined in the statute. Although a recent D.C. Circuit precedent holds to the contrary, the brief argued that the importance of the issue and the extent of EPA’s deviation from requirements imposed by clear statutory language warrant reconsideration of that precedent. In July 2015, the court of appeals ruled that it was bound by its precedents to hold that the MACT requirement is inapplicable when EPA “revises” a standard that complied with the MACT standard when it was originally promulgated.