Justice Department Sues Colorado Over Large-Capacity Magazine Ban

The Justice Department filed suit against Colorado on Wednesday, accusing the state of violating residents' Second Amendment rights by banning magazines that hold more than 15 rounds. Court documents filed in the U.S. District Court for the District of Colorado state that officials admitted the magazines are commonly used by law-abiding Americans for self-defense and other lawful purposes.

The lawsuit argues that making it a crime to sell, transfer or possess such magazines therefore violates the constitutional protection for arms in common use. The action follows a separate suit the Justice Department filed against the city of Denver on Tuesday over its ban on certain semiautomatic firearms.

Colorado's statewide measure, which tightened an original 2013 restriction, bars both the sale and possession of the magazines in question.

It notes that Colorado acknowledged the prevalence of the banned magazines while still imposing the prohibition. A 2024 industry report estimated that more than 448 million detachable rifle magazines holding 30 rounds or more were in use or on the market, with an additional 60 million magazines holding between 11 and 29 rounds.

The Justice Department described the state's policy as one that prioritizes political signaling over constitutional rights. Officials said the Civil Rights Division's Second Amendment section would continue to challenge restrictions on arms owned by tens of millions of Americans.

The lawyer told reporters that communities impacted by mass shootings do not need easier access to such equipment and accused the federal action of serving industry interests rather than defending constitutional rights. A representative of the Second Amendment Foundation welcomed the intervention.

The group stated it was pleased that federal authorities were addressing what it called open hostility toward the exercise of enumerated constitutional rights in certain jurisdictions. The original Colorado restrictions date to 2013. State officials expanded them in April 2025, a move the current lawsuit directly challenges as unconstitutional.

This case forms part of a series of federal challenges to state and local gun regulations under the current administration. Legal observers have noted that post-Heller jurisprudence has increasingly turned on empirical questions of whether regulated items qualify as arms in common use.

The Justice Department's filings in both the Colorado and Denver matters emphasize ownership numbers and admitted prevalence by the regulating jurisdictions themselves. The lawsuit does not seek immediate injunctive relief in its initial filing, though such requests often follow in similar Second Amendment cases.

Proceedings will unfold in federal district court in Colorado, where judges have previously handled challenges to the state's magazine restrictions.