Walter Coles on his Chatham, Va., property. He wants to mine the 119 million pounds of uranium ore said to be underneath. (Jay Westcott/For The Washington Post)

Supreme Court justices across the ideological spectrum seemed reluctant Monday to try to divine the reason that Virginia lawmakers decided back in the 1980s to ban the mining of uranium, since everyone agrees that is something the state has the right to do.

Lawyers for a company that wants to extract what is said to be the nation’s largest untapped deposit of uranium, in southern Virginia, urged the court to look behind the lawmakers’ actions. If legislators acted because of concerns about radiological safety, they said, that could violate the Atomic Energy Act, which places such responsibility not with the state but with federal regulators.

Washington lawyer Charles J. Cooper, representing Virginia Uranium Inc., said the state couldn’t use a ban on mining, which is within its jurisdiction, as a ruse for concerns about production of uranium and storage of radioactive waste, which are the province of the federal Nuclear Regulatory Commission.

But Cooper was bombarded from all sides with questions on how a court would determine that.

“I’m hard-pressed to come up with many other examples where we look at a state legislative purpose and decide its permissibility based on our assessment of legislative motive,” said Justice Neil M. Gorsuch, a conservative.

“Is this going to require deposing every single legislative member?” asked his liberal seatmate Justice Sonia Sotomayor.

New Justice Brett M. Kavanaugh, a conservative, wondered what the outcome would be if legislators had more than one reason for enacting the ban.

And liberal Justice Elena Kagan had another concern. “You would concede, Mr. Cooper, that two states with exactly the same statutes, it could come out different ways because the legislative history was different in the two states?” she asked.

“It could, your honor,” Cooper said.

Justice Ruth Bader Ginsburg wondered: “Suppose Virginia had said, ‘We think that the extraction is a dangerous activity, so we are justifying this ban on mining to protect the workers from the hazards associated with mining,’ ” not with the dangers of producing uranium or dealing with radioactive wastes.

“I would lose if that was the state of Virginia’s genuine purpose,” Cooper said.

But it wasn’t, he added. Cooper and Solicitor General Noel J. Francisco, representing the federal government, said the U.S. Court of Appeals for the 4th Circuit did not do enough to ascertain the legislature’s true motives.

If not, Francisco said, “you really are giving state and local governments a road map for undermining a multibillion-dollar industry.”

The company says approximately 119 million pounds of uranium ore lies beneath an old plantation just north of the Virginia-North Carolina border. It was valued in 2011 at roughly $7 billion. Prices have fallen since then, but it’s still a major haul.

The Virginia General Assembly has been skeptical of mining the uranium since the Coles family raised the issue in the early 1980s. Leery after the 1979 nuclear accident at Three Mile Island in Pennsylvania, the legislature passed a law in 1982 permitting uranium exploration but imposing a one-year ban on mining. It extended the ban indefinitely in 1983.

When uranium prices rose steeply in the early 2000s, Walter Coles and another local family formed Virginia Uranium to renew the project. They abandoned the legislative route after 2013, when newly elected Gov. Terry McAuliffe (D) vowed to veto any effort to lift the uranium ban. After that, the company — now part of a Canadian holding firm — focused on a court challenge.

But in a 2-to-1 ruling, a panel of the Richmond-based appeals court said it was not up to the courts to “decipher” Virginia’s reasoning and look for a violation. “We decline to examine why the Commonwealth chose to ban uranium mining, which it was plainly allowed to do,” Judge Albert Diaz wrote.

That flat statement might have left a bit of hope for the company to at least get a remand to a lower court for further examination of Virginia’s reasoning.

Several justices pushed back Monday at Virginia Solicitor General Toby J. Heytens’s assertion that because the ban is on mining, which the Atomic Energy Act does not cover, there is no need for further judicial probing.

“When you say don’t look at purpose, there I get off the boat because I think that’s our job as a court . . . in a relevant case to determine what the purpose of the statute is,” said Justice Stephen G. Breyer. “Sometimes it’s easy. Sometimes it’s tough.”

Justice Samuel A. Alito Jr. and Kavanaugh seemed most receptive to the argument that Virginia’s ban on mining might have been a pretext for concern about the production of uranium — referred to as milling — and the storage of waste. Kavanaugh ventured that the state was really concerned about the latter but the only tool it had was the former.

“When you’re regulating mining, you’re always regulating milling because you have the two together, but you can’t regulate milling,” he told Heytens. “But the two are interlinked in a way that I’m not sure you can disaggregate in the way you’re doing.”

Francisco provided the court with a test to determine the legislature’s intent. “I think that the way you would analyze this is by looking at the text, the legislative history, the historical context in which it was enacted and the plausibility of any permissible non-safety rationale that the state puts forward,” he said.

Some justices seemed interested in that if the case were returned to lower courts.

The case is Virginia Uranium v. Warren.