The Department of Justice has filed a landmark lawsuit against the District of Columbia, accusing its Metropolitan Police Department of enforcing a sweeping and unconstitutional ban on semi-automatic firearms in direct violation of the Second Amendment.

The lawsuit, filed Monday by the DOJ’s newly established Second Amendment Section, challenges D.C. laws that require registration of all firearms but prohibit the registration of AR-15 rifles and other common semi-automatic weapons — effectively making ownership of those firearms illegal within city limits.

“MPD’s current pattern and practice of refusing to register protected firearms is forcing residents to sue to protect their rights and to risk facing wrongful arrest for lawfully possessing protected firearms,” the Justice Department said in a statement announcing the action.

Attorney General Pamela Bondi called D.C.’s restrictions “an unconstitutional infringement” on the rights of law-abiding Americans.

“Washington, D.C.’s ban on some of America’s most popular firearms is an unconstitutional infringement on the Second Amendment,” Bondi said. “Living in our nation’s capital should not preclude law-abiding citizens from exercising their fundamental constitutional right to keep and bear arms.”

The lawsuit represents the first major enforcement action by the DOJ’s Second Amendment Section, established earlier this year to monitor state and local compliance with federal constitutional standards following a directive from President Donald Trump.

Assistant Attorney General Harmeet K. Dhillon, who leads the Civil Rights Division, said the department’s filing underscores a renewed federal commitment to defending the individual right to bear arms.

“This Civil Rights Division will defend American citizens from unconstitutional restrictions of commonly used firearms,” Dhillon said. “The newly established Second Amendment Section filed this lawsuit to ensure that the very rights D.C. resident Mr. Heller secured 17 years ago are enforced today — and that all law-abiding citizens seeking to own protected firearms for lawful purposes may do so.”

The complaint explicitly references the 2008 Supreme Court case District of Columbia v. Heller, which struck down D.C.’s previous handgun ban and affirmed that the Second Amendment protects the right of law-abiding citizens to possess firearms in their homes for self-defense.

That case was initiated in 2003 by Richard Heller, a D.C. special police officer who sued after being denied the right to own a handgun for home defense. The Court’s 5-4 decision became one of the most significant constitutional rulings on gun rights in U.S. history.

“Unfortunately, today, the District still prevents ownership of these very same weapons through a pattern and practice of broadly blocking gun registration,” the DOJ said. “Law-abiding citizens throughout our nation’s capital are facing wrongful arrests due to the enforcement of unconstitutional laws.”

D.C. officials have declined to comment on the pending litigation, but the city’s long-standing restrictions on semi-automatic firearms date back decades and have been a consistent flashpoint between local Democrats and Republican administrations in Washington. The D.C. government requires all firearms to be registered with the Metropolitan Police Department, yet its code prohibits the registration of semi-automatic rifles and many handguns that meet the federal definition of “common use” under Heller.

Gun rights advocates have long argued that the District’s registration regime effectively nullifies the Heller ruling. The DOJ lawsuit now gives the federal government’s imprimatur to that argument, asserting that D.C. continues to “openly defy the Supreme Court’s precedent.”

The case also marks an aggressive new phase in the Trump administration’s broader push to assert federal supremacy in constitutional rights enforcement. Since returning to office, President Trump has signed executive orders directing federal agencies to challenge what he calls “lawless blue-state restrictions” on constitutional freedoms, including gun ownership, free speech, and religious liberty.

Bondi said the D.C. case “sets a precedent for nationwide enforcement.”

“Every American has the right to self-defense,” she said. “The Constitution doesn’t end where city limits begin.”

The Metropolitan Police Department has faced increasing scrutiny in recent years for its enforcement of the city’s gun laws, with several lawsuits alleging unlawful arrests of individuals possessing legally purchased firearms from other states.

The DOJ is now inviting D.C. residents who believe they’ve been wrongfully denied gun registrations or faced unlawful enforcement actions to file complaints through the Second Amendment Section’s online portal.