His lawyers have already told Justice Department officials that, if their client is charged with the gun crime, they will challenge the law under the Second Amendment, according to a person familiar with the private discussions granted anonymity because they are not authorized to speak publicly. That could turn a case that is already fraught with political consequences into a high-profile showdown over the right to bear arms.

The dispute would come as the White House fights to tighten gun laws. And it could put conservative gun-rights enthusiasts, who typically criticize the Biden family, in unusual alignment with the president’s son.

Federal prosecutors are expected to soon finalize the Hunter Biden investigation. David Weiss, the U.S. attorney for Delaware who was appointed by former President Donald Trump, is leading the probe. Attorney General Merrick Garland said in May that Weiss is “capable of making any decisions that he feels are appropriate,” and that he won’t face political pressure. Weiss is widely reported to be examining potential tax crimes related to undeclared income, as well as Hunter Biden’s purchase of a handgun in October 2018.

When he bought the gun, Biden filled out a federal form on which he allegedly avowed that he was not “an unlawful user of, or addicted to” any “controlled substance,” POLITICO reported in 2021. But according to Biden’s 2021 memoir, he frequently used crack cocaine at the time.

“I was smoking crack every 15 minutes,” he wrote.

A lawyer for Hunter Biden declined to comment for this article. A White House spokesperson declined to comment as well, citing the fact that the president’s son is a private citizen and that the Justice Department probe is ongoing.

The Gun Control Act of 1968 prohibits unlawful drug users from possessing firearms. The Bureau of Alcohol, Tobacco and Firearms says this ban applies to people who have admitted to using illegal drugs in the 12 months before buying a gun. Violators can receive up to 15 years in prison.

But the provision, long considered an unassailable gun restriction, now faces challenges. Last June, the Supreme Court undid decades of lower-court jurisprudence about the Second Amendment. In New York State Rifle & Pistol Association v. Bruen, the court’s six-justice conservative majority ruled that contemporary gun restrictions must be consistent with those of the founding era.

This new constitutional test presents a massive opening for people working to loosen gun restrictions, since firearm laws in America’s founding era were, in some ways, extremely permissive. The president, meanwhile, called the ruling deeply troubling and said it “contradicts both common sense and the Constitution.”

Since Bruen, most courts have still upheld the law banning drug users from owning guns, according to Jeff Welty, a professor at the School of Government at the University of North Carolina who closely tracks gun cases. But several have ruled against it.

“A majority isn’t everybody,” Welty said. “And given how unsettled the law is in this area, I think anyone charged with a violation of that statute would give serious consideration to raising the Second Amendment as a defense.”

Just a week after Bruen was released, a federal district judge in Utah ruled that the prohibition on drug users owning guns was unconstitutional because of its vagueness. Judge Jill Parrish noted that the statute itself doesn’t define the word “user” and also doesn’t say how the timing of people’s drug use affects their right to own guns. Parrish’s ruling — which the government has appealed — was based on the Fifth Amendment, not the Second, so it did not cite the Supreme Court’s Bruen decision. But Bruen only strengthens challenges to the drug-user prohibition.

Just ask Judge Patrick Wyrick, a district judge in Oklahoma who ruled in February that the government could not use the statute to prosecute a defendant who was caught with a gun and had marijuana in his car. In an opinion that relied heavily on Bruen, Wyrick wrote that barring marijuana users from possessing guns “is inconsistent with the Nation’s historical tradition of firearm regulation.” He rejected the government’s attempts to defend the statute’s constitutionality, including the government’s citations to 19th century laws that restricted people from using firearms while drunk.

And in Texas in April, a district judge also ruled against the constitutionality of the law. That case involved charges against a woman who had both marijuana and psilocybin — a psychedelic — in her home. Judge Kathleen Cardone concluded that the ban was inconsistent with the Second Amendment and with America’s early history of gun regulation. The Justice Department has appealed the Oklahoma and Texas cases.

Other judges disagree. In another case from Texas, Judge Alan Albright threw out a Second Amendment challenge to the statute. Albright noted that Bruen said the Second Amendment only protects the gun rights of law-abiding citizens.

And in Mississippi, Judge Louis Guirola Jr. rejected a defendant’s effort to get his conviction under the statute tossed out. “[A]nalogous statutes which purport to disarm persons considered a risk to society — whether felons or alcoholics — were known to the American legal tradition,” Guirola wrote. The defendant has appealed.

Meanwhile, another challenge to the drug-users prohibition is pending close to home for Hunter Biden. In Pennsylvania, defendant Erik Harris was charged under the statute, and was also charged with lying on the federal form when he purchased his gun (a separate crime that carries a maximum of five years in prison). Harris pleaded guilty, but reserved his right to appeal the constitutionality of the charges. His appeal is before the 3rd Circuit Court of Appeals — a key court for Hunter Biden because it oversees Delaware, too.

The appellate panel in Harris’ case appears to be waiting to rule until the 3rd Circuit resolves another major Second Amendment case: Range v. Attorney General, a lawsuit challenging the law banning felons from possessing guns.

Second Amendment advocates haven’t reached a consensus on whether to support gun rights for people who use hard drugs, according to Joseph Greenlee, the director of constitutional studies at the pro-Second Amendment Firearms Policy Coalition. Greenlee, whose group argued on the plaintiff’s side in Range v. Attorney General, said his group believes that people who use marijuana shouldn’t be banned from buying guns.

“We oppose marijuana-based firearm prohibitions because we’ve seen enough evidence provided by the government to determine that it’s insufficient to justify such a ban,” he told POLITICO. “As far as other substance-based prohibitions go, we think the government should be required to demonstrate that users of that substance are especially dangerous.”

Greenlee added that his organization hasn’t yet taken a position on whether or not the Constitution allows the government to bar people who use hard drugs from possessing guns.

“If the government provided insufficient evidence to justify a substance-based ban, I wouldn’t say anything was out of the question,” he added.

Aidan Johnston, the director of federal affairs for Gun Owners of America, said that his group opposes the ban on drug users owning guns.

“Whatever merit one might imagine on a ban on users of controlled substances buying guns, if we don’t trust people to buy weapons why are we trusting them in society?” he said.

Others are keeping the issue at arms’ distance. That includes Larry Keane, who heads the gun industry trade association National Shooting Sports Foundation. His group has filed amicus briefs weighing in on a variety of Second Amendment cases. But not when it comes to hard drugs.

“We’re not working to get the law changed, at all,” he said. “It’s not on our radar at all.”

Given the conflicting rulings in the lower courts, the Supreme Court may one day have to resolve the statute’s constitutionality — and it’s not obvious how the court’s conservative majority would view the issue. Jacob Charles, a professor at Pepperdine’s Caruso School of Law who studies gun laws, said that Justice Samuel Alito could be particularly ambivalent.

“I could see him going either way,” Charles said, “obviously in favor of gun rights, but also in favor of strong law enforcement.”

Andrew Willinger, the head of the Duke Center for Firearms Law, said he would be surprised to see the statute thrown out as a whole.

“I personally doubt that that prohibition would fall entirely,” he said.