U.S. Supreme Court Rules EPA May Regulate Greenhouse Gas Emissions

In a 5–4 decision in Massachusetts v. EPA, the United States Supreme Court ruled that the Environmental Protection Agency (EPA) has the authority to promulgate regulations of greenhouse gas emissions, including carbon dioxide from vehicles. The Court further held that that EPA’s failure to do so in response to a rulemaking petition, without providing sufficient explanation, was arbitrary and capricious, and in violation of law.