The Supreme Court s conservative supermajority upended decades of precedent governing the ability of federal agencies to set regulations in a ruling on Friday.

The courts decision written by Chief Justice John Roberts, which overturns its 1984 finding in Chevron v. Natural Resources Defense Council, will cause a sea change in how federal agencies are able to regulate everything from climate change to artificial intelligence to labor and workplace practices. It marks a huge win for corporations, as it will be significantly harder for the government to write rules.

Courts must exercise their independent judgment in deciding whether an agency has acted within its statutory authority, Roberts wrote.

The decision is also a major power grab by the judicial branch, which will now play a bigger role as the final arbiter over which new regulations are allowed to stand and which will be struck down.

The ruling concerns two cases, Loper Bright Enterprises v. Raimondo and Relentless Inc. v. Department of Commerce. Jackson joined her liberal colleagues, Elena Kagan and Sonia Sotomayor, in dissenting in Relentless, which was a 6-3 decision, but recused herself from Loper Bright Enterprises.

The issue of whether to overturn Chevron came before the court after two fishing companies Relentless and Loper Bright Enterprises challenged regulations imposed in 2020 by the National Marine Fisheries Service that required fishing boats to pay the salary of the federal inspectors who ride on them. Lawyers for the fishing companies argued that the court should not only overturn the regulations, but also eliminate the deference afforded to agencies to write such regulations by the courts precedent in Chevron.

In Chevron, the Supreme Court crafted a doctrine that granted the federal government broad deference to enact regulations without judicial interference. It effectively stated that agencies had the power to enact regulations without having to wait for the courts to weigh in, unless the regulation was an unreasonable interpretation of the underlying law enacted by Congress that delegated regulatory authority to that agency.

But, Roberts wrote, agencies have no special competence in resolving statutory ambiguities.

Courts do, he added. The Framers anticipated that courts would often confront statutory ambiguities and expected that courts would resolve them by exercising independent legal judgment. Chevron gravely erred in concluding that the inquiry is fundamentally different just because an administrative interpretation is in play.

Roberts also took issue with the view that interpretation of ambiguous statutory provisions amounts to policymaking suited for political actors rather than courts, as a misconception of the judicial role.

By forcing courts to instead pretend that ambiguities are necessarily delegations, Chevron prevents judges from judging, Roberts wrote.

The courts new doctrine provides significantly less deference to agencies, while granting judges more power to strike down regulations if the court determines that Congress did not explicitly delegate authority to enact the specific regulation in question. The decision is a product of the changing ideological and partisan makeup of the courts and the executive branch.