The Supreme Court on Thursday limited how the EPA can regulate power plants. By a 6-3 vote, the court said that the Clean Air Act does not give the Environmental Protection Agency broad authority to regulate power plants. The ruling is seen as a hard blow to the Biden administration’s war on energy companies, and it also sent a warning shot to other regulatory agencies over their power to issue unilateral rulings by justices who criticized what they saw as the unchecked power of federal agencies.