A federal appeals court on Tuesday upheld Maryland’s ban on the sale and possession of military-style assault weapons in the state, raising the possibility of another Supreme Court showdown over gun laws.

In what’s known as an en banc hearing, the entire U.S. Court of Appeals for the Fourth Circuit heard oral arguments in the case in March, with the circuit ruling 10-5 Tuesday in favor of upholding the ban.

The law had been challenged several times over the years but a 2022 Supreme Court ruling, known colloquially as “Bruen,” reopened fresh challenges. The Bruen decision, authored by Justice Clarence Thomas, said gun laws should not be evaluated by whether they serve the public good, but if they’re aligned with the nation’s “historical tradition of firearm regulation.” That means courts are to compare current laws with historical analogs from the Revolutionary and post-Civil War Reconstruction eras.

In the opinion for the majority, Judge J. Harvie Wilkinson III, a Republican appointed by President Ronald Reagan, found there is a tradition of regulation of certain types of weapons throughout American history, meaning Maryland’s law could stand.

“[The law] is but another example of a state regulating excessively dangerous weapons once their incompatibility with a lawful and safe society becomes apparent, while nonetheless preserving avenues for armed self-defense,” Wilkinson wrote. “For these reasons, we decline to wield the Constitution to declare that military-style armaments which have become primary instruments of mass killing and terrorist attacks in the United States are beyond the reach of our nation’s democratic processes.”

The appellants in this case, a group of pro-gun nonprofits, an Anne Arundel County gun store and three state residents, have signaled they will appeal to the Supreme Court.

“We believe, much like in Kolbe, the court’s analysis is flawed and that the challenged law is unconstitutional,” Adam Kraut, the executive director of Second Amendment Foundation, wrote in an email. Kolbe was a previous unsuccessful challenger to Maryland’s assault weapons ban. Second Amendment Foundation is a party in the case and will file a petition for the Supreme Court to hear the case, with Kraut calling it an “excellent vehicle for the Court to settle this debate once and for all.”

Maryland lawmakers, led by then-Sen. Brian Frosh, passed the Firearms Safety Act in 2013 in the wake of the mass killing at Sandy Hook Elementary School in Connecticut. That law banned certain kinds of rifles and pistols, including the AR-15, the sale of high-capacity magazines in Maryland, and required would-be handgun owners to submit their fingerprints and undergo four hours of safety training. The entirety of the Fourth Circuit also heard a challenge to the handgun restrictions in March and a ruling is pending.

Reached by phone while on vacation in Norway, Frosh, a Democrat, was elated to hear the appeals court had upheld the law he championed during his last term as a state legislator.

“It’s very gratifying,” said Frosh, who also served two terms as Maryland attorney general from 2016 to 2022. “Had they done anything else, I think it would have put the United States in a terrible bind. We see these mass killings over and over and they’re done with these assault weapons.”

Frosh’s administration first litigated the challenge to the assault weapons ban, but the case stretched on and into the tenure of his successor, current attorney general and former Maryland Lt. Gov. Anthony Brown, also a Democrat. Brown, in a news release, called Maryland’s law common sense and said his office would continue to litigate in defense of laws restricting which types of firearms and accessories could be sold in the state.

“The court’s decision today will save lives,” Brown said. “Access to weapons of war that have no place in our communities causes senseless and preventable deaths.”

Gun safety and advocacy groups praised the Fourth Circuit’s ruling as a win for community safety.

”The challenge to this law is as cynical as it sounds, and we’re glad to see the Fourth Circuit uphold Maryland’s lifesaving assault weapons ban,” Noah Lumbantobing, spokesperson for March for Our Lives, wrote in an email.

Mark Pennak, of gun rights advocacy organization Maryland Shall Issue, said the majority of the Fourth Circuit “got it wrong.”

”They seem to think that an AR-15 is dangerous and unusual, when all it is is a low-powered semiautomatic rifle,” he said.

Pennak’s group is not a party in the case but supported overturning Maryland assault weapons ban.

”A lot of this is just hysteria,” Pennak said.

In the majority’s opinion, Wilkinson wrote that the Second Amendment does allow for the regulation of weapons like the AR-15, which has origins with the military and “phenomenal lethality.” AR-15s specifically are disproportionately used in mass shootings — they make up about 5% of all firearms in the U.S., but are used in a quarter of mass shootings, according to the judges’ opinion.

The five-judge dissent, authored by Judge Julius Richardson, a Republican from South Carolina, strikes a different tone. In that opinion, Richardson accusing the majority of cherry-picking regulations from the historical record and pigeonholing them to fit their argument, treating the Second Amendment like a “second-class right” subject to the “whimsical discretion of federal judges.”

“Appellants seek to own weapons that are indisputably ‘Arms’ within the plain text of the Second Amendment,” Richardson wrote. “While history and tradition support the banning of weapons that are both dangerous and unusual, Maryland’s ban cannot pass constitutional muster as it prohibits the possession of arms commonly possessed by law-abiding citizens for lawful purposes.”

This is story may update.