National Resources Defense Council v. United States Environmental Protection Agency

Pursuant to the Clean Air Act (CAA), the Environmental Protection Agency (EPA) (defendant) has the authority to regulate emissions standards in motor vehicles. Those standards must be technologically feasible. In the early 1980’s, the EPA promulgated standards for the particulate emissions from vehicles. The standards limited particulates to .60 grams per vehicle mile (gpm) in 1982 models and .26 gpm in 1985 model light-duty trucks and .20 gpm in 1985 light-duty vehicles. The 1985 standards were deemed feasible by the EPA based on two factors: (1) modifications that decrease the emissions output of engines; and (2) the development of aftertreatment technology, which removes particulates from a vehicle’s exhaust. Specifically, the EPA predicted that a device called a trap-oxidizer would be available for use in 1985 models, which would filter out particulates from exhaust and destroy those particulates periodically in order to preserve the capacity of its filter. The EPA made this prediction even though the filtering system of the trap-oxidizer had not been proven to be durable. General Motors (GM) and the National Resources Defense Counsel (NRDC) (plaintiffs) challenged the EPA’s standards, but for different reasons. GM challenged the standards as too stringent, arguing that the 1985 standard could not be achieved in that time period due to the uncertainty of the trap-oxidizer technology. The NRDC challenged the standards as too lenient.