The U.S. Department of Justice filed suit against the State of Colorado on May 6, 2026, challenging a 2013 state law that prohibits magazines capable of holding more than 15 rounds [1]. The complaint contends the restriction violates the Second Amendment, arguing that magazines holding more than 15 rounds are standard equipment for commonly owned firearms and that the state's characterization of them as "large-capacity" reflects a political framing rather than an accurate description [1][2]. The filing came one day after DOJ filed a separate suit against the City and County of Denver over a related firearms ordinance [1].
Colorado enacted the magazine-capacity limit in 2013 following the Aurora theater shooting, which killed 12 people and injured dozens more [2]. The law has remained in force for more than a decade and has withstood prior legal challenges in state and federal courts. The DOJ complaint was filed by the Civil Rights Division, with Deputy Attorney General Todd Blanche and Assistant Attorney General Harmeet K. Dhillon among the principal figures associated with the broader enforcement campaign [1][3]. The constitutional theory advanced by DOJ tracks the framework set out by the U.S. Supreme Court in New York State Rifle and Pistol Association v. Bruen (2022), which requires firearms regulations to be grounded in the historical tradition of American gun law [2].
Colorado Attorney General Phil Weiser announced that his office will defend the statute, framing the federal challenge as an intrusion on the state's authority to regulate firearms for public safety [2][3]. The back-to-back filings against Denver and then the state itself signal a coordinated litigation strategy by the Trump administration targeting Colorado's layered gun restrictions. Both cases are expected to proceed in the U.S. District Court for the District of Colorado [3].
The legal posture sets up a direct confrontation between federal Second Amendment doctrine, as reshaped by Bruen, and state legislative judgments about gun violence mitigation. Colorado will likely move to dismiss or seek summary judgment on historical-tradition grounds, while DOJ will press for injunctive relief. Given the circuit-level split developing across the country on magazine-capacity laws, the case carries potential for eventual Supreme Court review, particularly if the Tenth Circuit rules against the government and deepens that divide [2].