In a major development in the ongoing legal battle over California’s restrictive ammunition background check law, both the U.S. Department of Justice and a coalition of 26 states have filed amicus briefs supporting the plaintiffs in Rhode v. Bonta, a case challenging the constitutionality of California’s Proposition 63.

The briefs were submitted ahead of the Ninth Circuit’s en banc review scheduled for March 23, 2026. The lawsuit, brought forward by Olympic gold medalist Kim Rhode and others with the support of the California Rifle & Pistol Association (CRPA), contests California’s unique point-of-sale background check system for ammunition purchases. A three-judge panel previously ruled the law unconstitutional in July 2025, prompting California to request the full court’s review.

The Department of Justice’s amicus brief, led by the Civil Rights Division, argues that California’s law burdens the core right protected by the Second Amendment — the right to possess operable firearms — by restricting access to ammunition through a system described as “onerous,” “byzantine,” and “unprecedented.”

“California’s burdensome barriers have achieved their goal: Over a third of law-abiding citizens rejected in January 2022 still had not purchased ammunition six months later,” the DOJ brief stated, citing data from lower court rulings. The brief emphasized that the state’s background checks, which include fees, short validity periods, and high rejection rates for technical errors, do not reflect any historical tradition of firearm regulation.

Joining the federal government’s stance, 26 states filed a separate amicus brief supporting the plaintiffs, further demonstrating the case’s national importance. CRPA President and General Counsel Chuck Michel commented on the significance of the bipartisan support, saying, “This level of national and federal support for our case highlights just how audacious the State of California has been in restricting gun rights.”

Prop. 63, approved by California voters in 2016, introduced mandatory background checks for all ammunition purchases and outlawed out-of-state ammunition shipments to residents. The law has faced continued legal scrutiny for imposing barriers that plaintiffs argue infringe on constitutionally protected rights.

The Ninth Circuit’s en banc review will revisit whether California’s law meets the standard set by the Supreme Court in New York State Rifle & Pistol Association v. Bruen, which requires modern gun laws to be consistent with the nation’s historical tradition of firearm regulation.

The case could have major implications for California residents and beyond, as courts continue to define the scope of permissible firearm and ammunition regulations under the Second Amendment.

With the Department of Justice now backing the challenge and 26 states signaling alignment with gun rights advocates, the case has taken on new weight in the national conversation over Second Amendment protections.

The right to keep and bear arms must also include the right to access the necessary components to make that right meaningful — namely, ammunition. The DOJ’s rare support of this Second Amendment challenge reflects a growing recognition that California’s ammo background check scheme is not only historically unsupported but functionally designed to discourage law-abiding citizens from exercising their rights. As courts look to history and text for guidance, this case may serve as a significant benchmark for future challenges to overreaching firearm regulations.