In a ruling involving a challenge to a fisheries regulation, the court consigned to history a 1984 ruling called Chevron v. Natural Resources Defense Council. That decision had said judges should defer to federal agencies in interpreting the law when the language of a statute is ambiguous, thereby giving regulatory flexibility to bureaucrats.

It is the latest in a series of rulings in which the conservative justices have taken aim at the power of federal agencies, including one on Thursday involving in-house Securities and Exchange Commission adjudications. The ruling was 6-3, with the conservative justices in the majority and liberal justices dissenting.