In a 5-4 decision, the court said the Clean Air Act gives the Environmental Protection Agency the authority to regulate the emissions of carbon dioxide and other greenhouse gases from cars.
Greenhouse gases are air pollutants under the landmark environmental law, Justice John Paul Stevens said in his majority opinion.
The EPA had previously argued that the tailpipe emissions of greenhouse gases were out of its jurisdiction. A coalition of 12 states and 13 environmental organisations, frustrated with Bush Administration inaction and obstruction on global warming, took the EPA to court:
The court had three questions before it.
--Do states have the right to sue the EPA to challenge its decision?
--Does the Clean Air Act give EPA the authority to regulate tailpipe emissions of greenhouse gases?
--Does EPA have the discretion not to regulate those emissions?
The court said yes to the first two questions. On the third, it ordered EPA to re-evaluate its contention it has the discretion not to regulate tailpipe emissions. The court said the agency has so far provided a "laundry list" of reasons that include foreign policy considerations.
The majority said the agency must tie its rationale more closely to the Clean Air Act.
Justice Stevens' says his position "involves no judgement on whether global warming exists, what causes it, or the extent of the problem". The decision clears the way for the state of California to gain EPA approval for its own programme to limit tailpipe emissions. Federal law considers the state a laboratory on environmental issues and gives California the right to seek approval of standards that are stricter than national norms.
This is world-changing. California was the first state to introduce laws requiring catalytic converters to eliminate toxicity from fuel emissions, in 1975. This had implications for the rest of the world as it embraced the change. An additional benefit was the phasing out of high-octane leaded petrol that masks the effect of catalytic conversion.
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