The U.S. Department of Justice filed a civil lawsuit against the City and County of Denver on May 5, 2026, alleging that Denver's longstanding ordinance banning so-called assault weapons, including AR-15-style rifles, violates the Second Amendment [1]. The suit seeks a permanent injunction against enforcement of the ordinance and an order requiring Denver to adopt corrective policies [1]. Denver Mayor Mike Johnston responded by pledging to defend the ban in court [2].
Denver enacted the ordinance in 1989, making it one of the older municipal assault weapons restrictions in the country [3]. The DOJ's complaint was filed by the Civil Rights Division's newly created Second Amendment Section, a unit established under the Trump administration to pursue federal civil litigation against state and local gun regulations [1][2]. Attorney General Todd Blanche and Civil Rights Division head Harmeet K. Dhillon are the senior officials overseeing the section's docket [1]. The suit marks one of the first cases brought under that section, signaling a systematic rather than ad hoc enforcement approach to challenging firearms restrictions at the local level [1][2].
The legal theory underlying the complaint draws on the Supreme Court's 2022 decision in New York State Rifle and Pistol Association v. Bruen, which held that firearm regulations must be consistent with the historical tradition of firearms regulation in the United States [2]. Under that standard, DOJ argues that categorical bans on semiautomatic rifles commonly owned by law-abiding citizens lack sufficient historical grounding to survive constitutional scrutiny [1][3]. Denver's position, which the city has not yet formally filed, will likely contest both the historical analysis and the federal government's standing to bring a preemptive civil rights action against a municipality for local ordinance enforcement [2][3].
The case will be litigated in federal district court in Colorado [1]. Denver has the backing of city legal counsel and, according to Mayor Johnston's public statements, intends to mount a vigorous defense [2]. The outcome will carry weight beyond Colorado: several other cities and states maintain similar semiautomatic weapons bans, and a ruling against Denver could expose those ordinances to parallel DOJ suits or private litigation under the same legal framework [3].