Massachusetts v. EPA

Massachusetts v. Environmental Protection Agency, 549 U.S. 497 (2007), is a 5–4 U.S. Supreme Court case in which Massachusetts, along with eleven other states and several cities of the United States, represented by James Milkey, brought suit against the Environmental Protection Agency (EPA) represented by Gregory G. Garre to force the federal agency to regulate the emissions of carbon dioxide and other greenhouse gases (GHGs) that pollute the environment and contribute to climate change.

Under the Clean Air Act, Massachusetts argued that the Environmental Protection Agency was required by law to regulate "any air pollutant" which could "endanger public health or welfare." The EPA denied the petition, claiming that federal law does not authorize the agency to regulate greenhouse gas emissions.

The court ruled in favor of the plaintiffs, finding that greenhouse gases qualify as air pollutants. This led to the U.S. regulation of greenhouse gases under the Clean Air Act.

Background

In 1997 the United States Senate unanimously rejected the Kyoto Protocol because it did not set mandatory reduction targets for heavily polluting "developing" countries such as India and China. In 1999, a group of private organizations filed a rulemaking petition asking the EPA to regulate "greenhouse gas emissions from new motor vehicles under §202 of the Clean Air Act."

There were hopes that the incoming Bush Administration would direct the EPA to regulate carbon dioxide emissions. However, a few months into his first term in office, Bush clarified his view that carbon dioxide was not a pollutant under the Clean Air Act.

The EPA requested public comment on the rulemaking petition in 2001. The EPA denied the petition in 2003.