The Supreme Court issued a landmark decision Thursday curbing the power of federal agencies to interpret ambiguous laws, a ruling that could reshape how dozens of government bodies regulate everything from environmental standards to financial rules.

In a 6-3 decision, the justices held that courts must exercise independent judgment when interpreting statutes, rather than deferring to agency interpretations under the decades-old Chevron doctrine. The ruling marks one of the most significant shifts in administrative law in a generation.

Critics of the Chevron framework had long argued it gave unelected bureaucrats too much power to rewrite laws through regulation. Supporters of agency deference warned the decision would leave judges rather than subject-matter experts making complex policy calls.

The Biden administration argued the ruling would create chaos across federal rulemaking, citing pending regulations on everything from clean air standards to pharmaceutical approvals. Industry groups celebrated the decision as a check on executive overreach.

Legal scholars say the impact will take years to fully play out, as existing regulations built on Chevron deference face new legal challenges. At least 200 federal rules could be vulnerable to challenge under the new standard.