3 April 2007

In one of the most important decisions in environmental law, the US Supreme Court has ruled that carbon dioxide (CO2) is a pollutant and that the Environmental Protection Agency (EPA) has the right to regulate CO2 emissions from new cars.

The case Massachusetts v. EPA was brought by a group of 12 states (CA, CT, IL, ME, MA, NJ, NM, NY, OR, RI, VT, WA) and a number of local governments and environmental organizations. The court had been asked whether CO2 was a pollutant, and if the EPA had the right to regulate CO2 and other greenhouse gas (GHG) emissions from new cars. The EPA—supported by 10 states (AL, ID, KS, MI, NE, ND, OH, SD, TX, UT), four motor industry trade associations and two coalitions of utility companies—argued that under the Clean Air Act (CAA) it did not have the power to regulate CO2 emissions because carbon dioxide was not deemed to be a pollutant. Furthermore, a causal link between GHGs and climate warming was not unequivocally established, according to the EPA’s position.

But the Court decided that greenhouse gases fit well within the CAA capacious definition of “air pollutant”, and the EPA has statutory authority to regulate GHG emissions from new motor vehicles. It was a split ruling, with five judges voting in favor and four dissenting.

According to the ruling, EPA’s action not to regulate GHG emissions was “arbitrary, capricious, or otherwise not in accordance with law”. EPA must reconsider its decision, and ground its reasons for action or inaction in the CAA statute. Unless the EPA can show that CO2 is not involved in the global warming seen around the world, the EPA should regulate it.

While the ruling does not yet force Bush administration to take immediate action, it does pave the ground for a national GHG emission legislation in the United States. This is also realized by the automotive industry—in a statement on the ruling, the Alliance of Automobile Manufacturers said: “The Alliance of Automobile Manufacturers believes that there needs to be a national, federal, economy-wide approach to addressing greenhouse gases. This decision says that the US Environmental Protection Agency will be part of this process.”

Source: US Supreme Court opinion (Justice Roberts dissent | Justice Scalia dissent) | Alliance of Automobile Manufacturers response