The Supreme Court is poised to unleash a weapon against Biden's climate policies

• Supreme Court will likely discard the Chevron doctrine, which empowers federal agencies.
• The decision could make it easier for courts to block President Joe Biden's climate policies.
• Business and conservative groups argue the Chevron doctrine leads to federal overreach.

Climate advocates and business groups are closely watching the US Supreme Court this week.

The court could issue a ruling that sharply curtails the federal government's power to regulate the environment, including President Joe Biden's climate policies.

The case involves a group of commercial fishermen who opposed fees they had to pay to have federal observers aboard their vessels to prevent overfishing. But at the center is 40 decades of legal precedent known as the Chevron doctrine that has shaped the role of federal agencies.

Business groups and conservatives argue that the doctrine allows federal bureaucrats to overstep their authority on issues related not only to the environment but to broad swaths of the economy. The lawyers representing the commercial fisherman are from the Cause of Action Institute, a nonprofit group in the libertarian network built by Charles Koch, the petrochemicals billionaire who has advocated for deregulation.

Environmental groups are worried that overturning the Chevron doctrine will make it easier for courts to block regulations, especially those from the Biden administration designed to curb greenhouse-gas emissions that are warming the planet.

Here's what to know:

What is the Chevron doctrine?

Congress writes laws, and federal agencies write the rules to implement them. But Congress isn't always clear, and it doesn't regularly update old laws to reflect scientific or technological advancements.

The Chevron doctrine holds that when the law is ambiguous, courts should defer to the federal agency's interpretation, as long as it's reasonable. These agencies are often staffed by people with technical and scientific expertise that judges don't have.

That precedent stems from a 1984 court case over air-pollution rules issued by the Environmental Protection Agency under President Ronald Reagan. The decision was actually a defeat for environmentalists; the Natural Resources Defense Council had sought a more expansive definition of pollutants at big industrial plants like Chevron's but lost.

"The doctrine was neutral," said David Doniger, a senior attorney at the NRDC who argued the original Chevron case on behalf of the group. "It originally came up in a Reagan administration effort to weaken the Clean Air Act."

Doniger said that since then, the Chevron opinion has been cited more than 15,000 times by courts across the country. But he added that as the Obama and Biden administrations have pushed for stronger environmental policies, business groups and conservatives have come to see Chevron as "systematically enabling the government to do more."

Where do the justices stand?

Legal experts say the Supreme Court, with its conservative majority, is likely to overturn or significantly limit the Chevron doctrine.

Justice Neil Gorsuch, a Trump appointee, said in oral arguments in January that Chevron was problematic for small businesses and individuals with little power to influence federal agencies.

But Justice Elena Kagan, an Obama appointee, argued that health, safety, and environmental regulations protecting the public could be upended if Chevron were overturned.

What could be affected?

Doniger said that while reining in Chevron could make it easier to win cases aimed at rolling back Biden's climate policies, it's hard to make predictions without knowing the scope of the Supreme Court's ruling.

The EPA over the past year has set stricter limits on emissions from cars, trucks, power plants, and oil and gas infrastructure, as well as on toxic chemicals in tap water — all of which are the targets of lawsuits from Republican-led states, the fossil-fuel industry, or other businesses.

"Lawyers will try to characterize these rules as stretching EPA authority," Doniger said.

Meanwhile, he added, administrative lawyers have been preparing for this very scenario at the Supreme Court. Biden's EPA hasn't relied on the Chevron doctrine to defend its climate rules.

That's a departure from the Obama years, when the EPA cited the Chevron doctrine in its attempt to set the first limits on carbon emissions from power plants. Lengthy court battles ensued, and the Trump administration ultimately shelved the plan.

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