In back-to-back lawsuits filed this week, the Department of Justice sued Denver over its assault weapons ban and then sued Colorado over its statewide restriction on ammunition magazines capable of holding more than 15 rounds. Together, the lawsuits target some of the state’s most significant gun safety measures, including policies rooted in Colorado’s history of mass shootings at Columbine High School, a movie theater in Aurora, and a supermarket in Boulder.
The federal lawsuits argue that both the Denver ordinance and Colorado’s magazine restriction violate the Second Amendment rights of residents by prohibiting firearms and ammunition devices commonly owned throughout the United States. The cases also represent an aggressive expansion of the Justice Department’s role in challenging state and local firearm laws, with the administration framing the issue as a civil rights matter under the Constitution.
“Colorado’s ban on certain magazines is political virtue signaling at the expense of Americans’ constitutional right to keep and bear arms,” Assistant Attorney General Harmeet Dhillon, who leads the Civil Rights Division, said in a statement announcing the lawsuit against the state. “Under my direction, the Division’s Second Amendment Section will continue to defend law-abiding Americans’ rights against unconstitutional restrictions on their right to possess arms which are owned by tens of millions of their fellow citizens.”
The litigation follows formal warnings sent by Dhillon last week to Colorado and Denver officials demanding that they voluntarily stop enforcing their firearm restrictions by 5 p.m. Eastern time Tuesday or face federal lawsuits. Denver City Attorney Miko Brown rejected the demand before the department moved forward with its lawsuit against the city, calling the request “baseless, irresponsible, and a clear overreach of the federal government’s power.”
Colorado’s law limiting ammunition magazines to 15 rounds has been in place since 2013, when lawmakers approved the measure following the 2012 mass shooting at an Aurora movie theater that killed 12 people and injured dozens more. Denver’s assault weapons ordinance predates that law by decades, restricting the sale and possession of assault weapons since 1989. Both laws have long been flashpoints in the national debate over gun regulation, but the Justice Department’s intervention dramatically raises the legal and political stakes surrounding them.
The administration’s lawsuits contend that the firearm restrictions improperly target weapons and magazines that are commonly possessed by law-abiding gun owners. In the Denver case, the Justice Department directly attacked the terminology used by lawmakers and city officials to describe semiautomatic rifles restricted under the ordinance.
“‘Assault weapon’ is a rhetorically charged political term developed by anti-gun publicists,” the Justice Department said in its lawsuit against Denver. “In reality, the firearms the City calls ‘assault weapons’ include ordinary semiautomatic rifles possessed by millions of law-abiding Americans.”
The department made similar arguments in its challenge to Colorado’s magazine restriction, asserting that magazines capable of holding more than 15 rounds are standard components of many commonly owned firearms, including AR-15-style rifles. The lawsuits seek court orders blocking enforcement of the laws and requiring Colorado and Denver to adopt new policies and procedures consistent with the administration’s interpretation of the Second Amendment.
State and local officials responded defiantly, arguing that the federal government is attempting to override long-standing public safety measures enacted after repeated episodes of mass violence. Colorado Attorney General Phil Weiser, a Democrat currently running for governor, called the lawsuit against the state a “dangerous overreach” that “turns the mission of the DOJ’s Civil Rights Division on its head.”
“Large-capacity magazine laws are responsible policies that satisfy Second Amendment protections, decrease the deadly impacts of mass shootings, and save lives,” Weiser said in a statement. “The state has a duty to protect Colorado residents from gun violence, and I will vigorously defend our state large-capacity magazine limit law from this attack by the Trump Justice Department.”
Denver Mayor Mike Johnston also defended the city’s assault weapons ordinance while invoking Colorado’s history of mass shootings, including Columbine in 1999, Aurora in 2012, and the 2021 Boulder supermarket shooting. Johnston said the city would “not be intimidated” by the Justice Department’s attempt to overturn the law, which has remained in place for nearly four decades.
“It works,” Johnston said of the weapons ban.
The lawsuits arrive at a moment of intensifying conflict between gun-rights advocates and Democratic-led states pursuing stricter firearm regulations. Days before filing the Colorado and Denver cases, the Trump administration announced broader rollbacks of federal gun regulations, signaling a more aggressive posture toward gun-control measures nationwide. Colorado has become a particularly visible battleground because of both its history of mass shootings and its recent legislative efforts to tighten firearm restrictions.
In addition to the 15-round magazine limit, Colorado lawmakers last year approved a law requiring individuals purchasing semiautomatic firearms to complete training requirements. Efforts to prohibit the manufacturing, sale, and purchase of assault weapons failed in both 2023 and 2024, though the proposals would not have banned possession of existing firearms.
Colorado’s magazine restriction has already survived one major constitutional challenge. In 2020, the Colorado Supreme Court unanimously upheld the law after Rocky Mountain Gun Owners sued the state, ruling that the measure did not violate the Colorado Constitution’s right to bear arms. The current federal lawsuits, however, shift the dispute into the federal court system, where the cases could ultimately reach the U.S. Supreme Court.
Gun-rights groups in Colorado celebrated the Justice Department’s intervention, describing it as a long-overdue response to years of firearm restrictions enacted by Democratic officials. Ian Escalante, executive director of Rocky Mountain Gun Owners, said Colorado “has shown nothing but disdain for our God-given rights for the last decade.”
“They have been brazenly torching the Constitution and until now, have faced little to no repercussions,” Escalante said in a statement. “I pray this is the beginning of a recurring trend from the DOJ: systematically undoing all the damage inflicted on Coloradans by the tyrants in Denver, and the beginning of the end of the gun control apparatus here in Colorado.”
Gun safety advocates warned that overturning Colorado’s restrictions could weaken measures designed to reduce casualties during mass shootings and strip local governments of tools they consider essential for public safety. Janet Carter, managing director of Second Amendment litigation at Everytown Law, described the lawsuit as a “dangerous threat to public safety” and an attack on Colorado’s “life-saving magazine capacity limit.”
“Mass shooters using those magazines can fire dozens of rounds in seconds, and Colorado’s common sense measure has protected its residents for over a decade,” Carter said in a statement. “Coming just a day after their suit against Denver, it is clear that the DOJ is working to strip communities of the tools they need to keep people safe. We stand with Colorado and will fight to defend these constitutional, vital, and life-saving laws.”
The cases now place Colorado’s firearm restrictions at the center of a national legal battle over the limits of state and local gun regulation under the Second Amendment. With the Justice Department seeking to halt enforcement of laws enacted after some of the country’s deadliest mass shootings and Colorado officials pledging to defend them, the lawsuits could become a major test of how aggressively the federal government can intervene against state-level gun safety policies.
COMMENTS