DOJ Sues City of Denver Over Assault Weapons Ban, Calls Local Ordinance a Civil Rights Violation Under Second Amendment

Estimated reading time: 8 minutes

DENVER, CO — The United States Department of Justice has filed a federal lawsuit against the City and County of Denver and the Denver Police Department, alleging that Denver’s local “assault weapons” ban violates the Second Amendment rights of city residents and constitutes a pattern or practice of civil rights violations under federal law.

The complaint was filed on May 5, 2026 in the U.S. District Court for the District of Colorado as Case No. 1:26-cv-01929, United States of America v. City and County of Denver, Colorado, et al. The case is being prosecuted by the Department of Justice’s Civil Rights Division through its newly active Second Amendment Section, headed by Acting Chief Barry K. Arrington. Assistant Attorney General Harmeet K. Dhillon leads the Civil Rights Division.

The Ordinance Being Challenged

The lawsuit targets Denver Revised Municipal Code Chapter 38, Article IV, Section 38-121(c), which makes it unlawful “to carry, store, keep, manufacture, sell, or otherwise possess assault weapons within the City and County of Denver.”

The ordinance defines “assault weapon” broadly to include any semiautomatic pistol or centerfire rifle with a fixed or detachable magazine capacity of more than 15 rounds, any semiautomatic shotgun with a folding stock or magazine capacity of more than six rounds, any combination of parts designed to convert a firearm to those configurations, and any firearm modified to those configurations.

The ordinance covers some of the most popular semiautomatic rifles in America, including the AR-15 and similar platforms.

The DOJ’s Constitutional Argument

The complaint opens with the constitutional foundation. The Second Amendment “protects the right of law-abiding citizens to keep and bear arms in common use for lawful purposes,” citing District of Columbia v. Heller. Under New York State Rifle and Pistol Association v. Bruen, when the Second Amendment’s plain text covers an individual’s conduct, the Constitution presumptively protects that conduct, and the government must justify its regulation by demonstrating it is consistent with the nation’s historical tradition of firearm regulation.

The DOJ argues Denver’s ordinance fails both prongs of that test.

On the first prong, the complaint argues that AR-15 rifles are bearable arms and the ordinance therefore implicates the plain text of the Second Amendment. The ordinance is presumptively unconstitutional from the outset.

On the second prong, the DOJ argues that there is no historical tradition of banning arms in common use, and that AR-15 style rifles with standard capacity magazines are unambiguously in common use today. The complaint marshals significant evidence on this point.

The Numbers Behind “Common Use”

The complaint cites National Shooting Sports Foundation data showing at least 28 million AR-style semiautomatic rifles in circulation as of 2021. Approximately 2.8 million AR-style rifles entered the market in 2020 alone, accounting for roughly 20 percent of all firearms sold that year.

Various studies cited in the complaint estimate that between 16 million and 24.6 million Americans own or have owned AR-style rifles. The most commonly reported reasons for owning AR-style rifles include recreational target shooting (66 percent), home defense (61.9 percent), hunting (50.5 percent), defense outside the home (34.6 percent), and competitive sports shooting (32.1 percent).

The complaint also notes that Justice Elena Kagan recently wrote that “the AR-15 is the most popular rifle in the country” in Smith and Wesson Brands, Inc. v. Estados Unidos Mexicanos. The Bureau of Alcohol, Tobacco, Firearms and Explosives itself described AR-15 style rifles as “one of the most popular firearms in the United States” in 2022 federal rulemaking.

On the magazine capacity question, the complaint cites NSSF data showing at least 448 million magazines with capacity greater than 15 rounds in circulation in the United States. The DOJ also cites Colorado’s own prior court stipulations that AR-15 platform rifles are usually sold at retail with 30-round magazines and that the majority of AR-15 owners use magazines with 20 or 30 round capacity.

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Why “Assault Weapon” Is Treated as a Loaded Term

The complaint is direct about the political nature of the ordinance’s terminology. The DOJ writes that “assault weapon” is “not a technical term used in the firearms industry” but rather “a rhetorically charged political term developed by anti-gun publicists,” citing Justice Clarence Thomas’s dissent in Stenberg v. Carhart.

That framing matters. It signals that the DOJ is not just challenging the ordinance on outcome but also on the terminology itself, treating the ban as a fundamentally political rather than technical regulation.

The Civil Rights Statute

The DOJ is bringing this action under 34 U.S.C. Section 12601, the federal statute that allows the Attorney General to sue local governments engaged in a pattern or practice of conduct by law enforcement officers that deprives people of constitutional rights.

This is the same statute the DOJ has historically used to investigate and reform police departments accused of patterns of excessive force or unconstitutional practices. Applying it to a Second Amendment violation is a notable and aggressive use of federal civil rights enforcement authority.

The complaint argues that Denver Law Enforcement Officers are under a duty to enforce the ordinance, that they have routinely done so for years, and that they will continue to do so absent a federal injunction. Those enforcement actions, the DOJ contends, deprive Denver residents of their Second Amendment rights and therefore constitute a pattern or practice of unconstitutional conduct.

What the DOJ Is Asking the Court to Do

The complaint seeks declaratory and injunctive relief. Specifically, the DOJ is asking the court to declare that Denver and the Denver Police Department are governmental authorities under Section 12601(a), that Denver Law Enforcement Officers are law enforcement officers under that same provision, that enforcement of the ordinance constitutes a pattern or practice of conduct by law enforcement officers, and that the effect of that pattern or practice is to deprive Denver residents of their Second Amendment rights.

The DOJ is also asking for a permanent injunction barring Denver and its agents from enforcing the ordinance to the extent it bans possession of AR-15 style rifles with standard capacity magazines. The injunction would require Denver to adopt policies and procedures to remedy the unconstitutional conduct and to implement systems that identify and correct future conduct depriving people of constitutional rights.

Why This Matters

The Second Amendment is a fundamental civil right, and the DOJ filing this lawsuit signals a significant shift in how the federal government views local assault weapon bans. The case is being prosecuted by a dedicated Second Amendment Section within the Civil Rights Division, an office that did not meaningfully exist under the prior administration in this configuration.

This is the federal government using the same legal infrastructure historically deployed against police departments engaged in patterns of constitutional violations and applying it to municipal gun bans. The implications are significant. If this lawsuit succeeds, the Department of Justice will have established a template that can be used against any similar ordinance in any city in the country.

For armed citizens, this is also a clear signal that the executive branch is now treating the right to keep and bear arms as a civil right on the same footing as other constitutional rights protected by federal civil rights enforcement. That framing is overdue, and it changes the political and legal calculus for cities considering similar ordinances going forward.

The Broader Legal Landscape

The Denver case fits into a growing body of post-Bruen litigation. The Tenth Circuit recently ruled in National Association for Gun Rights v. Polis that Colorado’s state-level ban on possession of unserialized firearm parts implicates the Second Amendment’s plain text. The Supreme Court has heard or considered cases this term touching on multiple Second Amendment issues, and Justice Brett Kavanaugh’s statement in Snope v. Brown noted there is a “strong argument that AR-15s are in common use.”

The Tenth Circuit, where this case will be heard at the appellate level if it gets there, is also where USA Carry recently reported on the ghost gun ruling involving Colorado state law. The court has shown increasing willingness to engage seriously with Second Amendment claims under the Bruen framework.

What Happens Next

The City of Denver and the Denver Police Department will have an opportunity to respond to the complaint. The case will likely proceed through motions practice, possibly including a motion to dismiss from the city, before reaching the merits.

If Denver chooses to defend the ordinance, the city will bear the burden under Bruen of demonstrating a historical analogue from the founding era for banning AR-15 style rifles. Given the DOJ’s evidence that AR-15 style rifles are owned by tens of millions of Americans and are unambiguously in common use, that burden will be difficult to carry.