DOJ Sues Colorado Over Its Limit on Large-Capacity Gun Magazines
NEWS & RESEARCH
In May 2026, the US Department of Justice (DOJ) sued Colorado over a state law that bans gun cartridges that can hold more than 15 bullets. The law was originally passed after the 2012 mass shooting in a movie theater in Aurora in which a gunman used a large-capacity magazine to fire more than 60 rounds in less than a minute. That same week, the DOJ also filed a lawsuit against the city of Denver regarding a 1989 city ordinance that bans semiautomatic weapons. In both cases, the DOJ argued the gun safety laws violated the Second Amendment right to bear arms. State and local officials have vowed to stand up to the administration, with Denver City Attorney Miko Brown saying the DOJ's claims are "baseless, irresponsible, and a clear overreach of the federal government's power." State Attorney General Phil Weiser agreed, calling the DOJ's actions "dangerous," as they could put Coloradans at a greater risk of gun violence.
SOURCES: New York Times | Denver Post | CNN | Courthouse News | NOTUS
ANALYSIS & OPINION
During President Trump's second term, DOJ recruited top officials from some of the most hardline pro-gun organizations in the country and created a special section within its Civil Rights Division dedicated to challenging gun regulations—with the Colorado cases just the latest in a string of resulting lawsuits. According to one gun control advocate, the suits are a "perverse" use of that division, which was originally created to "root out…racism, police brutality, [and other] systemic problems." However, DOJ has a long road ahead: the Colorado Supreme Court already found in 2020 that the magazine ban does not violate the state constitution's right to bear arms, and six courts of appeals have found that similar ordinances banning large-capacity cartridges and assault weapons fully comply with the Second Amendment. Nevertheless, numerous legal experts believe that filing in Colorado was a strategic move by Trump's politicized DOJ to push its pro-gun agenda by involving "one of the more moderate circuits in the debate."
SOURCES: Washington Post | Bloomberg Law | Colorado Public Radio | 9News
HOW TO FIX IT
Federal action:
Pass the Assault Weapons Ban Act of 2025, which would essentially moot these state-by-state lawsuits by codifying restrictions at the federal level. The bill would prohibit the sale, transfer and possession of large-capacity gun cartridges holding more than 10 rounds of bullets and ban the manufacture and sale of semi-automatic rifles and pistols with military-style features, including the AR-15.
Amend 34 U.S.C. § 12601, the federal statute that the DOJ invoked in the lawsuits against Colorado and five other state and local governments. Passed in the wake of the Rodney King beating, the statute was created to address police brutality. It says that it is “unlawful for any government authority…to engage in a pattern or practice of conduct by law enforcement officers…that deprives persons of rights…protected by the Constitution.” According to the Duke Center for Firearms Law, the statute is “notably broad,” and the Trump administration has exploited that ambiguity to sue cities and states over their gun safety laws. Narrowing the statute to its original purpose would close that loophole.
Litigation:
US v. District of Columbia (DC): According to the Duke Center for Firearms Law, this case is the “litmus test” regarding the DOJ’s ability to file Second Amendment lawsuits against state and local governments. The DOJ sued DC over its ban on semi-automatic weapons, and legal experts are waiting to see if the court grants the District’s motion to dismiss on the basis that the challenge is outside the scope of § 12601. If so, the “theory underlying the Denver and Colorado complaints could collapse.”
Legislation: S.1531 - Assault Weapons Ban Act of 2025
