Beth Gardiner in Scientific American:
With its recent decision in West Virginia v. EPA, which reined in the Environmental Protection Agency’s authority to address climate change, the Supreme Court wrote into precedent an idea that has been gaining traction for years in conservative legal circles. The concept, known as the “major questions” doctrine, holds that regulatory agencies may not take actions with wide-ranging economic impact unless Congress has specifically authorized them to do so.
The case concerned the powers granted by the Clean Air Act, the landmark 1970 law that— in the absence of legislation specifically dealing with climate change—has been the best tool available for checking greenhouse gas emissions. And while the Court now constrains the federal government’s power to tackle big issues, the Clean Air Act was designed to address just such “major questions”—including, explicitly in its text, questions yet to be understood when it was enacted.