Court of Appeals for the First Circuit March 27, 2000, Nos. 98-1036, 99-2245 (Association of International Automobile Manufacturers, Inc. v. Commissioner, Massachusetts Department of Environmental Protection)

TORRUELLA, Chief Judge.

These consolidated appeals present an important issue of federal preemption under the Clean Air Act. Pursuant to § 177 of that act, the Commonwealth of Massachusetts adopted a set of automobile emission standards in 1993. Plaintiff-appellees (the “Manufacturers”) brought suit claiming that the Massachusetts regulations were preempted by the Clean Air Act.