Traditionally, courts give agencies substantial discretion to interpret broadly worded statutes Congress delegates to them within their areas of expertise. The Supreme Court acknowledged this principle in a 1984 case, Chevron v. Natural Resources Defense Council, noting that Congress entrusts implementation to agencies who are more expert than courts.

In Thursday's decision, the court ignored that precedent and embraced a radically different approach called the major questions doctrine, which holds that Congress does not authorize federal agencies to adopt regulations of major social and economic significance using broad legal language. The major questions doctrine displaces the traditional rule that courts will defer to agency interpretations of the statutes they are charged with administering. In practice, it means that federal agencies cannot adopt significant rules to respond to unforeseen challenges unless Congress anticipated their application of the statute and explicitly authorized it in advance.