Two U.S. Courts of Appeals have recently ruled¹ that §113 of the Clean Air Act² does not give the Environmental Protection Agency authority to require states, under pain of civil sanctions and penalties, to adopt or enforce particular transportation control measures as part of their implementation plans. The two decisions, which expressly reject a 1974 Third Circuit ruling that EPA does have such power under the Commerce Clause³ and §113, have dealt a blow to the beleaguered Agency's ability to lead and administer effectively the national air pollution control program.

The magnitude of the task of controlling air pollution from auto emissions in certain metropolitan areas was underestimated by EPA in its initial attempts to implement the Clean Air Act. It soon became clear that in some cities, because of topographic features or the sheer numbers of automobiles, the legislatively-mandated 90 percent reduction in per-vehicle emissions levels would not be enough by itself to assure achievement and maintenance of the health-related primary air quality standards established for certain pollutants. This was brought home to EPA by judicial rulings in City of Riverside v. Ruckelshaus⁴ and Natural Resources Defense Council, Inc. v. Environmental Protection Agency,⁵ which essentially ordered the Administrator to promulgate regulations, including restrictions on transportation if necessary, for the control of photochemical oxidants (a product of automobile exhausts and sunlight) and carbon monoxide, and to disapprove state implementation plans that did not provide for the timely attainment and maintenance of the national standards for these two pollutants.