EPA’s Clean Air Act can regulate pollutants but not CO2

Justice Scalia wrote the dissent on MASSACHUSETTS v. EPA on Apr 2, 2007:

Numerous entities, including the Commonwealth of Massachusetts, asked the EPA to judge that carbon dioxide (CO2) was a pollutant causing global warming and, acting under the Clean Air Act (CAA), to make rules restricting its release by newly manufactured automobiles. The EPA declined to do so.

HELD: Delivered by Stevens; joined by Kennedy, Souter, Ginsburg & Breyer

The plaintiffs have standing for a federal case. Massachusetts, in particular could make a showing of injury (rising coastal water levels), causation (an incremental lowering of CO2 would be helpful), and remedy (the EPA could effect an incremental lowering). The EPA believed that Congress did not intend the EPA to regulate substances that cause climate change. The EPA, however, should find CO2 (among other gases) falls within the definition of a pollutant because it is a “substance” that is “emitted into the ambient air.”

DISSENT #1: Roberts dissents; joined by Scalia, Thomas & Alito

The plaintiffs do not have standing because they can show no concrete injury, the evidence of causation by greenhouse gases of rising coastal water in Massachusetts was minimal (and undercut by its own expert’s affidavit), and there was no showing that a rule issued by the EPA could provide measurable relief to the plaintiffs. The plaintiffs’ claim cannot truly be resolved by decision of a federal court.

DISSENT #2: Scalia dissents; joined by Roberts, Thomas, & Alito

It was a reasonable interpretation by the EPA of the CAA that Congress intended the EPA to regulate air pollution in the “ambient air,” that is, air at or near the surface of the earth, not the upper reaches of the atmosphere where greenhouse gases are said to have their detrimental effects. Further, nothing in the CAA, not even a petition for regulations, requires the EPA to make a “judgment” that a pollutant should be regulated, and the Court is not free to order the EPA to do so.