(Reuters) - The en banc 4th U.S. Circuit Court of Appeals took a bold and potentially controversial stand Tuesday in its decision on the constitutionality of Maryland’s ban on military-style semi-automatic weapons and large-capacity magazines.

Like two other federal appellate courts that have reviewed similar bans in other states, the 4th Circuit found in Kolbe v. Hogan that such laws are subject to intermediate scrutiny, which means governments must only show that their gun prohibitions advance an important state interest. Under intermediate scrutiny, the 4th Circuit majority said in an opinion by Judge Robert King, Maryland “has shown all that is required: a reasonable, if not perfect, fit between the (law) and Maryland’s interest in protecting public safety.”

That holding resolves what had been a split in the federal circuits on the correct level of scrutiny for laws that impinge on Second Amendment rights. The District of Columbia and 2nd Circuits have both evaluated gun control laws using intermediate scrutiny but the three-judge panel that previously heard the Kolbe case applied the tougher standard of heightened scrutiny to strike down the Maryland ban in 2016. (Two additional circuits, the 9th and the 7th, have also upheld gun bans, but did not specifically opine on the appropriate level of scrutiny.) Tuesday’s en banc decision from the 4th Circuit replaces the 2016 panel ruling and aligns all of the appellate courts that have considered the standard for reviewing gun prohibitions.

But that is not the big news from Judge King’s opinion, which was joined in full by nine of the 14 judges who heard the en banc appeal. The 4th Circuit held that Maryland’s ban on military-style assault rifles is constitutional regardless of the standard of scrutiny because the Second Amendment does not give civilians a right to own such weapons.

That’s right: According to the 4th Circuit, the military-style guns used in a disproportionate share of the mass killings in the U.S. are outside the aegis of the Second Amendment because they are most suited for military use.

Gun rights advocates are not going to like this decision at all, not least because it turns the words of their favorite U.S. Supreme Court ruling, 2008’s District of Columbia v. Heller, against them. In the Heller opinion, Justice Antonin Scalia struck down the District’s ban on handguns, holding that the Second Amendment gives citizens a right to own weapons “in common use at the time.” Justice Scalia said, however, that not every gun meets that definition. “The Second Amendment does not protect those weapons not typically possessed by law-abiding citizens for lawful purposes,” he wrote in Heller. Specifically, the Heller opinion cited “the historical tradition of prohibiting the carrying of ‘dangerous and unusual weapons,’” such as “weapons that are most useful in military service—M–16 rifles and the like.”

Justice Scalia’s terminology doesn’t offer much instruction on how to determine if a weapon is “in common use at the time” or “dangerous and unusual,” as the 4th Circuit en banc majority pointed out. In fact, one of the big arguments by plaintiffs who challenged Maryland’s ban – and by the four 4th Circuit judges who dissented from the en banc opinion – was that semi-automatic weapons, otherwise known as “modern sporting rifles,” are among the most popular guns on the market, with 8 million of them circulating in the U.S. as of 2013. The weapons are clearly in common use, according to this theory, so they’re within the ambit of the Second Amendment.

The majority focused instead on Justice Scalia’s concession that governments may prohibit “weapons that are most useful in military service—M–16 rifles and the like.” The semi-automatic weapons banned under Maryland’s law were adapted from M-16s and other automatic rifles developed for military use, according to the 4th Circuit. That fact, the court said, put them within the category of weapons the Heller opinion excepted from Second Amendment protection.

“We are convinced that the banned assault weapons and large-capacity magazines are among those arms that are ‘like’ ‘M-16 rifles’ — ‘weapons that are most useful in military service’ — which the Heller Court singled out as being beyond the Second Amendment’s reach,” the 4th Circuit said. “Put simply, we have no power to extend Second Amendment protection to the weapons of war that the Heller decision explicitly excluded from such coverage.”

The dissent, in an opinion by Judge William Traxler, complained that the majority “has gone to greater lengths than any other court to eviscerate the constitutionally guaranteed right to keep and bear arms.” (The majority responded that although its holding on the scope of the Second Amendment “may seem novel in some quarters, it is solidly predicated on the plain language of Heller and was raised and argued by the state in both the district court proceedings and this appeal.”) Judge Traxler said that millions of law-abiding Americans own semi-automatic weapons for lawful purposes, including the defense of their homes, so the guns are squarely within the Second Amendment. The judge – who had written the Kolbe panel opinion now replaced by the en banc decision – also reiterated his conclusion that Maryland’s law is subject to strict scrutiny.

It’s worth reading the 4th Circuit’s entire 116-page en banc opus on Maryland’s gun law, opinions and dissent. The majority opinion, written by the judge who had dissented from the Kolbe panel’s ruling in 2016, is a thorough review of litigation over state and local gun control measures, including a discussion of recent mass shootings perpetrated with weapons subject to the Maryland ban and analysis of the evidence both sides presented on the efficacy of gun control laws. (Spoiler alert: The federal ban on semi-automatic assault weapons didn’t reduce gun violence as much as proponents had hoped but gun control backers blame grandfather provisions inserted by gun rights advocates.)

In a passionate concurrence, Judge Harvey Wilkinson wrote about empowering voters, not courts, to decide whether to adopt gun restrictions. “To say in the wake of so many mass shootings in so many localities across this country that the people themselves are now to be rendered newly powerless, that all they can do is stand by and watch as federal courts design their destiny – this would deliver a body blow to democracy as we have known it since the very founding of this nation,” he wrote.

The Supreme Court, as I wrote last June and as the 4th Circuit majority pointed out in the Kolbe en banc decision, has so far chosen not to review appellate opinions upholding gun control laws in the wake of Heller. I won’t be surprised if gun rights advocates ask the justices to overturn the 4th Circuit, but the majority opinion gives Maryland a good argument that even if the appeals court was wrong about the scope of the Second Amendment, there is no need for the Supreme Court to get involved because the 4th Circuit would have reached the same conclusion examining the Maryland law under intermediate scrutiny – the consensus standard among federal appellate courts.