The Trump Justice Department filed a federal lawsuit against Denver on Monday, demanding a court order to block the city from enforcing a ban on semiautomatic rifles that has been on the books since 1989. The suit names both the City and County of Denver and the Denver Police Department as defendants and frames the case as a straightforward Second Amendment violation.
Acting Attorney General Todd Blanche did not mince words.
"The Constitution is not a suggestion and the Second Amendment is not a second-class right."
The complaint, filed through the DOJ Civil Rights Division's Second Amendment Section, argues that Denver's ordinance bans firearms that tens of millions of Americans lawfully own, including AR-15-style rifles with standard-capacity magazines. Federal lawyers called the AR-15 the most popular rifle in the United States and said Denver's prohibition on its sale, carry, and possession cannot survive constitutional scrutiny, the Daily Caller reported.
Denver's ordinance dates to 1989. It prohibits so-called assault weapons and magazines holding more than 15 rounds, National Review reported. For 37 years, the city has treated an entire class of commonly owned semiautomatic rifles as contraband within its borders.
The DOJ complaint zeroes in on that point. It argues that the rifles Denver banned are not exotic military hardware but standard civilian firearms protected by the Second Amendment.
"When the City banned AR-15 style rifles with standard capacity magazines, it banned an arm in common use for lawful purposes by law-abiding citizens."
That language, drawn directly from the federal complaint, mirrors the analytical framework the Supreme Court reinforced in its 2022 Bruen decision, which held that firearms regulations must be consistent with the nation's historical tradition of gun regulation. Under Bruen, a ban on commonly owned arms faces a steep constitutional climb.
The Denver suit is one of the first major actions by the DOJ's newly created Second Amendment Section, a unit housed inside the Civil Rights Division and built specifically to challenge restrictive state and local gun laws, the Washington Times reported. Assistant Attorney General Harmeet K. Dhillon confirmed the section is leading the case.
The creation of that section signals the administration views local gun bans not as policy disagreements but as civil rights violations. That framing carries real legal weight: the DOJ is seeking both declaratory and injunctive relief, asking a federal court to declare Denver's ordinance unconstitutional and to order the city to stop enforcing it against AR-15-style rifles.
The move fits a broader pattern. The Trump administration has been overhauling ATF operations and proposing the repeal of Biden-era background-check rules, treating Second Amendment enforcement as a policy priority across multiple agencies.
The lawsuit did not come without warning. Before filing, the DOJ pressured Denver to repeal its ordinance voluntarily. Mayor Mike Johnston refused, the Washington Examiner reported. Johnston's defiance set the stage for a direct federal challenge to one of the oldest municipal gun bans in the country.
The mayor's position puts Denver squarely in the crosshairs of an administration that has shown little patience for blue-city resistance on constitutional questions. Whether Johnston's stand reflects genuine legal confidence or political calculation, the city now faces the full weight of the federal government in court.
The clash echoes other recent confrontations between the Trump administration and Democratic-led jurisdictions. Federal courts have become the primary arena for these fights, from appellate battles over deportation flights to disputes over energy permitting and law enforcement policy.
Denver is not the only target. Federal officials have also signaled potential legal action against Colorado's statewide ban on large-capacity magazines, the Associated Press reported. That threat suggests the Denver lawsuit may be the opening salvo in a broader campaign against Colorado's gun-control regime.
If the DOJ follows through, Colorado could face simultaneous federal challenges to both its local and statewide firearms restrictions. For a state that has steadily tightened gun laws over the past decade, the legal exposure is substantial.
The question of whether semiautomatic rifle bans survive constitutional review remains unresolved at the Supreme Court level. Several justices have signaled interest in taking up the issue, and the Washington Times noted that legal observers see the Denver case as a potential vehicle for a definitive ruling. The Eleventh Circuit's recent decision upholding the federal machine gun ban drew a sharp line between machine guns and semiautomatic rifles, a distinction the DOJ is now pressing in Denver's case.
The core legal question is narrow but consequential: Does a municipal ban on semiautomatic rifles that millions of Americans own for lawful purposes violate the Second Amendment?
Under the Bruen framework, the government bears the burden of showing that a firearms regulation is "consistent with this Nation's historical tradition of firearm regulation." Denver will need to identify historical analogues for banning an entire class of commonly owned rifles. That is a heavy lift. No founding-era or Reconstruction-era law banned the most popular long arm of its day from civilian possession.
The DOJ's complaint leans hard on the "common use" doctrine, which traces back to the Supreme Court's 2008 Heller decision. Heller held that the Second Amendment protects arms "in common use at the time" for lawful purposes. Federal lawyers argue the AR-15 plainly qualifies.
Investigators and litigators on both sides will need to build historical records. Denver must demonstrate that its 37-year-old ban fits within a recognized tradition of arms regulation. The DOJ must show that no such tradition supports banning America's most widely owned rifle platform. The outcome could reshape gun law not just in Denver but across every jurisdiction that maintains a similar ban.
The political dimension is hard to ignore. Blue-city gun bans have long operated in a kind of legal twilight, rarely challenged by a federal government willing to spend resources on litigation. That calculus has changed. The creation of a dedicated Second Amendment Section inside the Civil Rights Division means the DOJ now has permanent institutional capacity to bring these suits, not just in Denver but anywhere local law conflicts with federal constitutional protections.
For Democratic mayors who have treated gun restrictions as settled local policy, the Denver lawsuit is a wake-up call. The federal government is no longer content to let these ordinances stand unchallenged. And for gun owners in Denver who have lived under a 37-year ban on rifles their neighbors in other states buy legally every day, the suit represents the first real prospect of relief.
The broader pattern of legal conflict between the Trump administration and blue-state governments shows no sign of slowing. If anything, the Denver case suggests the administration is expanding the front lines.
Denver passed its ban in 1989. For nearly four decades, the city treated a class of constitutionally protected firearms as illegal contraband. No federal administration forced the question until now.
When a city spends 37 years ignoring the Bill of Rights, it should not be surprised when the Bill of Rights finally shows up in court.
