Engine Manufacturers Ass'n v. South Coast Air Quality Management District

Respondent South Coast Air Quality Management District (District) is a political subdivision of California responsible for air pollution control in the Los Angeles metropolitan area. and parts of surrounding counties that make up the South Coast Air Basin. It enacted six Fleet Rules that generally prohibit the purchase or lease by various public and private *249fleet operators of vehicles that do not comply with stringent emission requirements. The question in this case is whether these local Fleet Rules escape pre-emption under § 209(a) of the Clean Air Act (CAA), 81 Stat. 502, as renumbered and…