The Supreme Court on Friday ruled to limit the power of federal regulatory agencies, upending a 40-year precedent widely known as the Chevron Doctrine that generally had courts show deference to agency experts in disputes over ambiguities in the law.

       The 6-3 opinion was authored by Chief Justice John Roberts.

       "Chevron is overruled," Roberts wrote. "Courts must exercise their independent judgment in deciding whether an agency has acted within its statutory authority, as the [Administrative Procedure Act] requires."

       "Careful attention to the judgment of the Executive Branch may help inform that inquiry. And when a particular statute delegates authority to an agency consistent with constitutional limits, courts must respect the delegation, while ensuring that the agency acts within it," Roberts continued. "But courts need not and under the APA may not defer to an agency interpretation of the law simply because a statute is ambiguous."

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       Roberts clarified the court's ruling was forward-looking and would not impact past cases that relied on the doctrine.

       Justice Elena Kagan, in her dissent, defended the rule as being the "backdrop against which Congress, courts, and agencies—as well as regulated parties and the public—all have operated for decades."

       "It has been applied in thousands of judicial decisions," Kagan wrote. "It has become part of the warp and woof of modern government, supporting regulatory efforts of all kinds—to name a few, keeping air and water clean, food and drugs safe, and financial markets honest. And the rule is right."

       This is a developing story. Please check back for updates.