The Supreme Court on Monday announced it will hear a case that could significantly scale back federal agencies’ authority, with major implications for the future of environmental and other regulations. The justices next term will consider whether to overturn a decades-old precedent that grants agencies deference when Congress left ambiguity in a statute. Named for the court’s decision in Chevron U.S.A. v. Natural Resources Defense Council, the Chevron deference has become one of the most frequently cited precedents in administrative law since the decision was first handed down in 1984. It involves a two-step test: First, judges decide if Congress...