type: timeline_event Supreme Court ruled 6-3 that the EPA lacked authority under the Clean Air Act to regulate greenhouse gas emissions from power plants through generation shifting, formally establishing the "major questions doctrine" for the first time by name in a majority opinion. Chief Justice Roberts authored the majority, joined by Justices Thomas, Alito, Gorsuch, Kavanaugh, and Barrett. The decision held that when regulatory actions involve "vast economic and political significance," agencies must show clear congressional authorization rather than relying on general statutory language. Roberts wrote that Congress must "speak clearly" when authorizing agency action of such magnitude. The ruling invalidated the Obama administration's Clean Power Plan and constrained EPA's ability to address climate change, the most urgent environmental crisis facing humanity. The major questions doctrine represents a fundamental shift in administrative law, transferring regulatory policymaking power from expert agencies to courts and requiring explicit congressional authorization for significant regulations. Justice Kagan's dissent, joined by Breyer and Sotomayor, condemned the majority for substituting judicial judgment for agency expertise and blocking climate action: "The Court appoints itself—instead of Congress or the expert agency—the decisionmaker on climate policy. I cannot think of many things more frightening." Within days, litigants began citing West Virginia to challenge other agency actions, including nuclear waste licensing and financial regulations. The doctrine undermines Chevron deference, which had directed courts to defer to reasonable agency interpretations of ambiguous statutes. The decision advances corporate interests by hamstringing environmental and consumer protection regulations, requiring industry-friendly legislative language before agencies can address emerging threats. Combined with the Court's other democracy-undermining rulings, West Virginia v. EPA demonstrates how the Roberts Court systematically dismantles the regulatory state to serve plutocratic interests while blocking climate action that threatens fossil fuel profits.