(WASHINGTON) -- In a unanimous decision, the Supreme Court on Thursday ruled that a longstanding federal ban on guns for unlawful users of any controlled substance is unconstitutional as applied to a Texas gun owner who used marijuana several times a week.
The decision set new limits on federal prosecution of gun owners who are targeted simply for having a history of drug use. It was especially welcomed by millions of American cannabis users who have had to disarm or risk up to 15 years behind bars.
Justice Neil Gorsuch wrote in the court's opinion that unlawful drug use alone cannot be grounds to seek to send someone to prison and potentially force them to give up firearms for life.
"We do not question that sometimes an individual's unlawful use of marijuana (or any other controlled substance) may render him a danger to others," Gorsuch wrote. "But, again, the government disclaims the need to show anything like that in this case. ... affording the government that kind of broad power to designate any group as dangerous and thereby disqualify its members from having a gun would risk allowing it to quickly swallow the Second Amendment."
The Justice Department has said it prosecutes roughly 300 cases a year in which a violation of the drug-user gun ban is a leading charge.
Gorsuch said the opinion was narrow and did not disturb other provisions of the law, which includes a ban on guns for drug addicts, ban on guns for people presently intoxicated and prohibition of firearms for those deemed a danger to themselves or others.
The ruling would not, for example, have prevented the prosecution of Hunter Biden under the law since he was a known and admitted drug addict while in possession of a firearm.
The decision was most immediately a victory for plaintiff Ali Hemani, a Texas man who admitted to using marijuana "every other day" while keeping a Glock 9mm pistol in his home. He was prosecuted by federal authorities for a single charge of unlawful possession as a drug user but was neither intoxicated nor physically holding the weapon when arrested.
A federal appeals court tossed out the Hemani indictment saying the ban as applied to him was unconstitutional. The justices agreed with that decision.
While more than 40 states have legalized marijuana in some form, it remains prohibited under federal law.
"Today's unanimous 9-0 decision makes it clear that the government cannot make it crime for people to own a gun, which the Supreme Court has held is a fundamental constitutional right, simply because they use marijuana," said Cecillia Wang, legal director at the American Civil Liberties Union.
"With nearly half of Americans reporting marijuana use at some point in their lives, this ruling protects the rights of millions and curbs the government's ability to impose arbitrary and discriminatory penalties," Wang wrote in a statement. "The court has sent a strong message that the government cannot criminalize the conduct of large numbers of people by making categorical and unfounded assumptions about whether they are dangerous."
The decision was also praised by the National Rifle Association as "a major victory for the Second Amendment and peaceable gun owners across America."
"No one should be deprived of their God-given right to keep and bear arms for engaging in nonviolent conduct, and there is no historical justification for doing so," said NRA-ILA Executive Director John Commerford in a statement to ABC News.
Gun safety advocates, which had joined the Trump administration in opposing a rollback of the drug-user gun ban, said the bulk of the law remains a robust and "common-sense" public-safety measure.
"Although the Court said that the particular law at issue in this case cannot be upheld specifically as to the person challenging it, it reaffirmed the ability of legislatures to restrict firearms access by certain categories of people," said Kris Brown, president of Brady, a gun safety group.