The Supreme Court looks like it is ready to overturn one of the most widely cited legal cases on the books, ushering in a potential sea-change in how the federal government operates.

Chevron v. Natural Resources Defense Council instructs courts to defer to a federal agency's "reasonable" interpretation of an ambiguous law.

Defenders of Chevron say that without it, judges would be left to decide complex policy questions that are better left to "experts."

But critics, including the Supreme Court's own conservatives, have grumbled that Chevron gives too much power to those experts while undermining the constitutional power of the courts to review the law.

Supreme Court reviews agency power

For years now, the conservative legal movement has targeted Chevron as a bedrock of the so-called administrative state, regarded by many as an unconstitutional "fourth branch" of government.

The actual cases before the nine justices Wednesday dealt with commercial fishermen who are challenging federal regulations requiring them to pay for observers on their vessels. That was merely the setting for a high-level argument about the relative scope of judicial and executive power.

Biden's Solicitor General, Elizabeth Prelogar, warned that discarding Chevron would cripple the federal government with a systemic "shock." The conservative justices were skeptical.

Brett Kavanaugh suggested that Chevron is responsible for violent see-saws in policymaking from one administration to the next, while Neil Gorsuch pointed to the inconsistent application of the precedent - with some courts making use of it and others not.

"Shouldn’t that be a clue that something needs to be fixed here?” he asked.

Court split down the middle

The court's three liberal justices echoed the Biden administration, with Elena Kagan suggesting that keeping Chevron would be an act of judicial humility. She brought up a hypothetical law regulating artificial intelligence.

“Congress knows that there are going to be gaps because Congress can hardly see a week in the future with respect to this subject, let alone a year or a decade in the future,” Kagan said.

She added, “judges should know what they don’t know.”

A lawyer for the fishermen, Roman Marinez, told the Supreme Court that even if they agreed with the fishermen, under Chevron, they would still have to adopt the reasoning of federal agencies, a standard "not consistent with the rule of law.”

Chevron, he said, "mandates judicial bias and encourages agency overreach" in a way that "threatens individual liberty."

The biggest question now is where John Roberts and Amy Coney Barrett will fall on the issue. Stay tuned.