US EPA must rethink regulating greenhouse gases, says Supreme Court

The US' Environmental Protection Agency may be forced to act on greenhouse gas emissions in car exhaust following a decision by the highest court in the land. The Supreme Court's decision in Massachusetts v Environmental Protection Agency has held that

• the EPA has the statutory authority to regulate greenhouse gas emissions from new motor vehicles, because they fall within the definition of "air pollutant" in the Clean Air Act; and,
• its stated reasons for refusing to do so - that at this stage it would be unwise to regulate greenhouse gases - were not consistent with the statute. Under the Act, the EPA can only decline to act if there is insufficient information to determine if the public health or welfare would be endangered, but it refused to act on other grounds.

This decision does not in itself mean that the EPA must regulate the greenhouse gas emissions in car exhaust. It does however make it harder for the EPA to refuse to do so, given the way the Court has interpreted the Clean Air Act and the EPA's duties under it. This opens the door for similar actions applying to other sectors of the economy.

For Australia, the implications are not direct ones - this case turned on the interpretation of the specific words of a US law - and it is hard to determine its precise effect. While it is not direct legal precedent, the decision is of great interest: the US is at the forefront of climate change litigation and the case does point to the use of existing environmental legislation as a way to control greenhouse gas emissions. It could be another strategy used in the courts here to combat greenhouse gas emissions, joining those tactics already used in cases such as Gray.