Cook County, Illinois has banned the AR-15 since 1993. So has Connecticut, in its own way. Now the Supreme Court has to decide whether either state was ever allowed to do that in the first place, and the answer could reshape gun laws in a dozen states.

The case is Viramontes v. Cook County, and it has been folded together with a companion case from Connecticut, Grant v. Higgins, because both raise the identical legal question. Cutberto Viramontes and Christopher Khaya are Cook County residents who each want to legally own a rifle the county bans: an AR-15 for Viramontes, an AK-style Galil for Khaya. Along with two national gun rights groups, the Firearms Policy Coalition and the Second Amendment Foundation, they sued in 2021, arguing that Cook County’s “assault weapons” ordinance violates the Second Amendment. The ordinance bans more than a hundred rifles by name, including the AR-15, plus any semiautomatic rifle with certain features like a pistol grip or a folding stock.

The case wound through the lower courts slowly. A federal district judge ruled for Cook County, leaning heavily on a 2023 decision from the Seventh Circuit Court of Appeals called Bevis v. City of Naperville, which had already upheld a nearly identical Illinois law. The Seventh Circuit affirmed that ruling in 2025. The Supreme Court agreed to hear the case on June 30, 2026, granting one hour of argument time for both consolidated cases combined. The question the Court will answer is whether the Second and Fourteenth Amendments guarantee the right to possess AR-15 platform and similar semiautomatic rifles.

To understand what is actually being argued, it helps to know two cases the justices have already decided. In District of Columbia v. Heller (2008), the Court first recognized that the Second Amendment protects an individual’s right to own a gun for personal use, separate from any connection to militia service. Heller also set a limit on that right: weapons that are “dangerous and unusual,” like the ones “most useful in military service,” can still be restricted. Then in 2022, in New York State Rifle & Pistol Association v. Bruen, the Court laid out a two-step test for judging modern gun laws. First, does the Second Amendment’s plain text cover what the person wants to do? If yes, the law is presumptively protected. Second, can the government show the law fits within America’s historical tradition of firearm regulation, going back to the founding era? If the government can’t, the law falls.

That framework is exactly what the two sides fight over. Viramontes argues that AR-15s are obviously “arms” under the Second Amendment’s text, since Heller defined that word broadly to cover essentially any bearable weapon, and that they are clearly not “unusual,” since Americans own tens of millions of them (his brief cites surveys estimating 16 to 24 million owners) and openly buy and sell them in most states. He argues the Seventh Circuit invented a rule that doesn’t exist in Heller: that any weapon resembling a military rifle, like the fully automatic M16, can be banned regardless of how many ordinary people actually own one for hunting, target shooting, or self-defense. Cook County counters that the historical tradition Bruen requires actually supports treating weapons built for military-style rapid, high-powered fire differently from firearms designed for personal, proportionate self-defense, a distinction it traces back to English common law limits on excessive force. The county’s brief leans on the AR-15’s ballistics, its use in mass shootings including the 2022 Uvalde school shooting, and testimony that its wounds are especially devastating, to argue the rifle simply isn’t the kind of weapon the founding generation would have protected for civilian ownership.

Listen for the justices to press on where exactly “common use,” the idea that a widely owned weapon can’t be “unusual,” fits into Bruen’s two steps. Lower courts have openly disagreed: does a weapon’s popularity settle the question at step one, or does it only matter once the government has to defend its law with history at step two? That placement affects who has to prove what. Also watch how much weight the justices put on comparing the AR-15 to the M16, since the two fire at very different rates in practice even though they share a basic design, and on what history actually shows about regulating “military-style” weapons versus regulating weapons based on how dangerous or unusual they are. A few of the justices have already signaled interest in this exact issue outside this case: Justice Brett Kavanaugh wrote last year that AR-15 owners have “a strong argument” the rifle is protected, while stressing the Court hadn’t yet decided the question.

This term already gave a preview of how the current Court applies Bruen. In back-to-back rulings this past June, the justices unanimously struck down a federal ban on gun possession by casual marijuana users and, in a 6-3 decision, struck down a Hawaii law restricting guns on private property, both times finding the government failed to produce close enough historical precdents. How the Court extends that reasoning to a weapon as widely owned, and as controversial, as the AR-15 is the question of this case.