The Supreme Court heard oral arguments this week on a couple of cases that could completely upend the way federal agencies regulate just about anything in the US. At question is a legal doctrine called Chevron deference that allows federal agencies to interpret laws meant to protect consumers, public health, and the environment. Now, a conservative supermajority in the Supreme Court appears on the precipice of either overturning or limiting the scope of Chevron deference.

The Verge spoke with legal experts about what’s going on and what the Supreme Court’s decisions on Chevron deference could ultimately mean for Americans. “The real question is how far they will go?” says Jody Freeman, director of the Environmental and Energy Law Program at Harvard. “They could in fact, overturn that precedent. And that could lead to considerable uncertainty and chaos.”

What is the Chevron doctrine?

Essentially, it lets judges defer to federal agencies when it comes to figuring out how to implement a law if there are disputes over how to interpret the language Congress passed. The assumption is that the agency has more expertise on the matter than a federal judge assigned to the case.

The practice was already in place long before it had a name, according to Ian Fein, senior counsel at the nonprofit Natural Resources Defense Council. It came to be known as the Chevron doctrine after a 1984 case, Chevron USA, Inc. v. Natural Resources Defense Council (NRDC). The funny thing is that NRDC, an environmental group, actually lost the case, and the Supreme Court upheld a decision that favored Chevron. It allowed the Ronald Reagan era’s industry-friendly Environmental Protection Agency to stick with its own lax interpretation of the Clean Air Act.

But since then, Chevron deference has empowered agencies to take initiative on issues that legislation might not have caught up to yet, like climate change and broadband access. It’s led to tussles, for instance, over how far the EPA can go to regulate greenhouse gas emissions under the Clean Air Act and how far the FCC can go in mandating net neutrality.

Why is the Supreme Court weighing in on it now?

Despite initial support from conservative groups, Fein says the Chevron deference has become a target more recently for industries pushing a deregulatory agenda. “There has been this steady march in the last 10 years or so of a concerted effort to try to call the doctrine into question and to have it overruled,” Fein tells The Verge. Around the second term of the Obama administration, Fein says, “We begin to see the notion of overturning Chevron deference as a way to cut back on federal agencies’ ability to carry out federal law.”

Two cases have worked their way up to the Supreme Court that jeopardize the long-standing Chevron doctrine: Loper Bright Enterprises v. Raimondo and Relentless, Inc. v. Department of Commerce. Plaintiffs in both cases are challenging a rule that makes fishing companies pay for the cost of observers they’re legally required to bring on their ships to monitor their operations. They’re asking justices to overrule Chevron and have backing from other industry groups ranging from Gun Owners of America to e-cigarette manufacturers.

“Joe Biden – and his predecessors – used the wide authority given to them by Chevron deference to go after law-abiding gun owners on several different occasions,” Gun Owners of America senior vice president Erich Pratt said in a statement last year. “Americans have had enough of one man with a pen going after our constitutionally guaranteed rights, and we urge the Court to reverse Chevron.” 

If they’re successful, they could force a total overhaul of how industries are regulated in the United States — taking power away from federal agencies and placing way more responsibility on federal courts.

“It’s kind of hard to overstate just how widespread and foundational this principle has been to the operation of our federal government,” Fein says. “It described the ground rules or the foundation on which the system that we have [operates] — of federal agencies carrying out statutes and courts, they’re the backstop.”

What happens if SCOTUS decides to overturn Chevron?

“It would really unleash a kind of chaotic period of time where federal courts are deciding what they think all these laws mean,” Freeman tells The Verge. “And that can lead to a lot of inconsistency and confusion for agencies and for regulated parties.”

Freeman has an entire interview in The Harvard Gazette that breaks down how badly such a decision could muck up courts:

Chevron does not matter much to the Supreme Court, which largely ignores it. But it does matter to the lower courts, which continue to use its two-step test to manage a flood of litigation challenging agency interpretations of every kind, from the most general to the most intricate. When statutes aren’t clear, courts consider whether the agency interpretation is sensible, well-reasoned, and aligns with the statute’s design. If so, the agency wins. Without Chevron, federal judges may get bogged down in intricate questions of statutory interpretation which require scientific, economic, or technological expertise. Policy choices that are better suited to agencies with research and information-gathering capacity, and obligations to consult stakeholders, will increasingly be made by federal judges, who have none of their expertise and do none of these things. 

Even Trump-appointed justice Brett Kavanaugh acknowledged that throwing out Chevron deference could be a “shock” to the legal system during oral arguments on Wednesday, although he downplayed the effects of that shock in the long term. He brushed it off, saying there are “shocks to the system every four or eight years when a new administration comes in, whether it’s communications law or securities law or competition law or environmental law,” The New York Times reports.

While Chevron deference as we know it may not survive the 6-3 conservative supermajority in the Supreme Court, the justices could opt to set limits on when to grant deference rather than throwing out the doctrine altogether. “Either way, it’s a moment, I think, in which it will be harder for federal agencies to do the work that they have to do,” Freeman says. And when congressional gridlock is a major barrier to passing legislation, it often falls on federal agencies to take action.

So this is a big deal, huh?

Yup. There’s a lot more at stake than catching fish.

“This will be a very important decision for the balance of powers between Congress, the President, and the courts. That’s why the stakes are so high,” Freeman says. “It looks like the Supreme Court is becoming more and more powerful with respect to the other two branches. And we should be worried about that.”

The Supreme Court has made a series of decisions lately that weaken federal agency power — notably, strengthening the “major questions” doctrine in a decision on West Virginia v. Environmental Protection Agency. According to that doctrine, courts don’t have to defer to federal agencies in matters of major national significance that Congress has yet to explicitly write into legislation.

The Supreme Court is expected to issue its decision on Chevron deference by late June.