The Supreme Court has changed a regulatory framework that has been in place for four decades, broadening the authority of federal judges to overturn decisions made by agencies on environmental, consumer, and workplace safety policies, among others.

In a 6-3 ruling, the court abandoned a 1984 precedent that instructed federal courts to defer to agency legal interpretations when statutory language from Congress was ambiguous. Conservative legal activists, Republican-led states, and some business groups have argued that the 1984 Chevron v. Natural Resources Defense Council decision allowed regulators to overextend their authority.

This decision is a significant milestone in a series of Roberts Court rulings that limit federal power, whether exercised by Congress or executive branch agencies. Earlier this week, the court ruled that Congress overstepped by allowing the Securities and Exchange Commission to enforce securities fraud through in-house hearings and blocked Environmental Protection Agency regulations aimed at reducing cross-state air pollution.

By discarding the Chevron deference doctrine, the justices have given dissatisfied parties—often businesses and property owners—more opportunities to challenge regulations by convincing federal judges that agency officials exceeded their authority.

“Agencies do not have special competence in resolving statutory ambiguities. Courts do,” Chief Justice John Roberts wrote for the majority, which included Justices Clarence Thomas, Samuel Alito, Neil Gorsuch, Brett Kavanaugh, and Amy Coney Barrett. Roberts emphasized that the Administrative Procedure Act of 1946, which outlines the federal rule-making process, required judicial deference to agency factual and policy determinations, but not to their legal interpretations.

“Even when an ambiguity involves a technical matter, it does not mean that Congress has removed the courts’ authority to interpret the statute and handed it to the agency,” Roberts wrote. “Courts do not decide such questions in isolation,” but rely on detailed briefs and evidence submitted by the parties, including extensive records and reports from expert agencies.

Justice Elena Kagan, in dissent, argued that the majority’s decision undermines public interest by diminishing the role of expert agencies and reducing the democratic accountability of policy decisions, shifting authority from executive branch officials to the unelected judiciary.

“Agencies are intimately familiar with the programs they manage,” some of which “involve policy choices and trade-offs between competing goods,” she wrote, joined by Justices Sonia Sotomayor and Ketanji Brown Jackson. “Agencies report to the President, who is accountable to the public for policy decisions; courts lack such accountability and proper basis for making policy.”

Overturning this long-standing “cornerstone of administrative law,” she wrote, replaces a rule of judicial humility with judicial overreach.

Prior to this decision, the conservative-dominated court had already been curtailing federal regulatory power, striking down Biden administration policies on public health measures for COVID-19 and a blanket cancellation of student-loan debt. While the Supreme Court had not cited Chevron for authority in recent years, many lower courts felt bound by the doctrine as long as it remained established law.

The court has been particularly skeptical when the administration attempted to address new issues using broad language from older statutes, developing a “major questions doctrine” that presumes agencies lack authority for actions with significant consequences without specific Congressional authorization.

“By ending Chevron deference, the court has taken a significant step to preserve the separation of powers and limit unlawful agency overreach,” said Roman Martinez, who represented a fishing boat company in one of the regulatory challenges before the court. “Judges will now interpret the law independently, without deferring to government agencies,” he said.

White House press secretary Karine Jean-Pierre criticized the decision, stating the court once again sided with special interests, undermining protections for clean water, public health responses, and student debt relief.

President Biden has instructed his legal team to collaborate with the Department of Justice and other agency counsel to review the decision and ensure that the federal workforce continues to safeguard public safety and community well-being, Jean-Pierre said.

While the ruling appears neutral, it offers a new tool for business interests seeking to challenge environmental, consumer, or workplace safety regulations in conservative-leaning federal courts. Reactions to the ruling were sharply divided along predictable lines.

“The previous Supreme Court deference allowed each new administration to push their political agendas through changing regulations, making it difficult for businesses to plan and invest,” said Suzanne Clark, president of the U.S. Chamber of Commerce, which supported overturning Chevron.

Conversely, labor groups were concerned about the impact: “This ruling paves the way for corporate challenges to the Occupational Safety and Health Administration, the National Labor Relations Board, and other agencies that protect workers’ rights and safety,” said AFL-CIO President Liz Shuler.

The Chevron doctrine, initially celebrated by conservatives for requiring courts to defer to Reagan administration policies, was later utilized by Democratic administrations to advance regulatory agendas. With three conservative justices appointed by former President Donald Trump, activists saw an opportunity to challenge Chevron, ultimately focusing on cases involving the National Marine Fisheries Service.

Lower courts in Boston and Washington, D.C., upheld the regulations under Chevron deference, prompting conservative advocacy groups to appeal to the Supreme Court to overturn the 1984 precedent.

Some experts believe the symbolic impact of overruling Chevron may outweigh its practical effects, noting that lower courts had already begun to move away from deference to agency decisions.