In a Supreme Court term increasingly dominated by cases related to former President Donald Trump, the justices are about to take up lower profile but vitally important cases that could rein in a wide range of government regulations affecting the environment, workplace standards, consumer protections and public health.

In cases being argued Wednesday, lawyers for the fishermen are asking the court to overturn a 40-year-old decision that is among the most frequently cited high court cases in support of regulatory power. Lower courts used the decision to uphold a 2020 National Marine Fisheries Service rule that herring fishermen pay for monitors who track their fish intake. A group of commercial fishermen appealed the decision to the Supreme Court.

Billions of dollars are potentially at stake in front of a court that, like the rest of the federal judiciary, was remade during Trump’s presidency by conservative interests that were motivated as much by weakening the regulatory state as social issues including abortion.

The 1984 decision in the case known colloquially as Chevron states that when laws aren’t crystal clear federal agencies should be allowed to fill in the details.

“If you’re deferring to the agency’s interpretation of the law, you’re allowing the agency to be a judge in its own case,” said Mark Chenoweth, president of the New Civil Liberties Alliance, which is representing fishermen based in Rhode Island. A second case, involving boats based in Cape May, New Jersey, is also being argued Wednesday.

The alliance, funded by conservative donors including the Koch network, says it’s “committed to cutting the administrative state down to size.”

Gun, e-cigarette, farm, timber and home-building groups are among the business groups supporting the fishermen. Conservative interests that also intervened in recent high court cases limiting regulation of air and water pollution are backing the fishermen as well.

David Doniger, a senior lawyer for the environmental advocacy group Natural Resources Defense Council, said the real agenda of Chevron opponents is “to hobble modern government.”

The Supreme Court could limit the damage, but it’s unclear it will, Doniger said.

“Will it be a tinkering change or a radical one?” he said. “If the latter, it threatens to wreck effective government.”

Environmental and health advocacy groups are urging the court to leave the Chevron decision in place. Health care groups led by the American Cancer Society warn of “the tremendous disruption that overruling Chevron would cause to publicly funded health insurance programs specifically, to the stability of this country’s health care system generally, and to the health and wellbeing of the patients and consumers we serve.”

Defenders of the decision may face a difficult climb. The court’s 6-3 conservative majority, including three Trump appointees, has been increasingly skeptical of the powers of federal agencies. At least four justices — Clarence Thomas, Samuel Alito, Neil Gorsuch and Brett Kavanaugh — have questioned the Chevron decision.

Gorsuch, as an appeals court judge, noted that court decisions “permit executive bureaucracies to swallow huge amounts of core judicial and legislative power and concentrate federal power in a way that seems more than a little difficult to square with the Constitution of the framers’ design.”

The public face of the court fight is the fishermen who ply the waters off the East Coast for herring and other fish.

Federal law already requires their boats to carry monitors who gather data, including how much “by-catch,” species other than the kinds their permits allow, is swept up.

But a 2020 regulation would require the herring boats to pay for the monitors, which could top $700 a day.

The Cause of Action Institute, an anti-regulatory group that used to share office space with an arm of the Koch network, identified the issue as a way to attack the Chevron decision and recruited the fishermen to sue, said Ryan Mulvey, a lawyer with the institute.

The lawsuits argued that Congress never gave federal regulators authority to require the fisherman to pay for monitors. They lost in the lower courts, which relied on the Chevron decision to sustain the regulation.

The Supreme Court agreed to hear the case, unpersuaded by arguments that no one has yet been forced to pay the fee or that the regulation was developed by regional councils that included industry representatives.

The fishermen have accepted the presence of the monitors only grudgingly.

“I wouldn’t say they get in the way. It’d be if someone came to sit in your living room for a week and watch what you do,” said Leif Axelsson, the co-captain of the fishing boat Dyrsten and a third-generation fisherman.

On a recent tour of the 160-foot-long (49-meter-long) vessel at its Cape May dock, Axelsson moved about the boat as though he’d been aboard his whole life. The Dyrsten was built for the family business when he was a small boy.

From the captain’s chair, Axelsson can see more than a dozen computer screens, about half of which help the crew find and catch fish.

There are fewer herring to catch in recent years. A scientific survey found in 2020 that herring has been overfished, leading the federal government to slash the amount of herring that can be caught. Among the uses of the fish is as bait by lobster fishermen.

Fishermen caught more than 100 million pounds of the fish as recently as 2017, but the 2021 catch was less than 11 million pounds. At the same time, the government has provided millions of dollars to help the fishermen cope with the decline.

Axelsson and other fishermen in Cape May who are involved in the Supreme Court case say they expect the quotas to be increased in the coming years.

Forty years on, it’s easy to forget that environmental groups actually lost the Chevron case by a 6-0 vote of the court, which upheld a lenient, industry-favored interpretation of an air pollution regulation. Three justices were recused.

Justice John Paul Stevens wrote the court’s opinion. “Judges are not experts in the field, and are not part of either political branch of government,” Stevens wrote in 1984, explaining why they should play a limited role. Justice Sandra Day O’Connor, who died last month, was the last surviving member of that court.

The current crop of justices takes a more robust view of judicial power. The Supreme Court itself hasn’t invoked the Chevron decision since Trump’s justices began arriving on the court in 2017, the first year of the Republican’s administration.

But lower courts continue to rely on Chevron. That should change, lawyer Paul Clement told the justices on behalf of Axelsson and other Cape May fishermen.

“Thus, the question is less whether this Court should overrule Chevron,” Clement wrote, “and more whether it should let lower courts and citizens in on the news.”

A decision in the cases is expected by early summer.