WASHINGTON — The Supreme Court upended a 40-year-old decision Friday that made it easier for the federal government to regulate the environment, public health, workplace safety and consumer protections, delivering a far-reaching and potentially lucrative victory to business interests.

The court’s six conservative justices overturned the 1984 decision colloquially known as Chevron, long a target of conservatives. The liberal justices were in dissent.

Billions of dollars are potentially at stake in challenges that could be spawned by the high court’s ruling. The Biden administration’s top Supreme Court lawyer had warned that such a move would be an “unwarranted shock to the legal system.”

The heart of the Chevron decision says federal agencies should be allowed to fill in the details when laws aren’t crystal clear. Opponents of the decision argued that it gave power that should be wielded by judges to experts who work for the government.

“Courts must exercise their independent judgment in deciding whether an agency has acted within its statutory authority,” Chief Justice John Roberts wrote for the court.

Roberts wrote that the decision does not call into question prior cases that relied on the Chevron decision.

But in dissent, Justice Elena Kagan said the assurance rings hollow. “The majority is sanguine; I am not so much,” she wrote.

Kagan called the latest decision “yet another example of the Court’s resolve to roll back agency authority, despite congressional direction to the contrary.”

The court ruled in cases brought by Atlantic herring fishermen in New Jersey and Rhode Island who challenged a fee requirement. Lower courts used the Chevron decision to uphold a 2020 National Marine Fisheries Service rule that herring fishermen pay for government-mandated observers who track their fish intake.

Conservative and business interests strongly backed the fishermen’s appeals.

The court’s conservative majority previously reined in environmental regulations and stopped the Democratic Biden administration’s initiatives on COVID-19 vaccines and student loan forgiveness.

The justices hadn’t invoked Chevron since 2016, but lower courts had continued to do so.

Forty years ago the Supreme Court ruled 6-0, with three justices recused, that judges should play a limited, deferential role when evaluating the actions of agency experts in a case brought by environmental groups to challenge a Reagan administration effort to ease regulation of power plants and factories.

“Judges are not experts in the field, and are not part of either political branch of government,” Justice John Paul Stevens wrote in 1984, explaining why they should play a limited role.

Opponents of the Chevron doctrine argue that judges applied it too often to rubber-stamp decisions made by government bureaucrats. Judges must exercise their own authority and judgment to say what the law is, the court said Friday, adopting the opponents’ arguments.