A federal judge blocked a California law on Wednesday which would have required background checks for individuals seeking to buy ammunition. The judge found that the California law, known as Proposition 63, violated the US Constitution’s Second Amendment right to keep and bear arms.

In 2016, California voters passed Proposition 63, which established background check requirements with US Department of Justice databases for individuals seeking to purchase ammunition. The proposition passed with over 62 percent of the vote, and the provisions went into effect in July of 2019.

A group of plaintiffs challenged Proposition 63 in addition to sections of the California Penal Code, on constitutional grounds. Together, the proposition and the penal code prohibited individual purchases and the importation of ammunition from other states.

US District Judge Roger Benitez based his decision on the US Supreme Court’s holding in New York State Rifle and Pistol Association v. Bruen, which stated:

[W]hen the Second Amendment’s plain text covers an individual’s conduct, the Constitution presumptively protects that conduct…[T]he government must demonstrate that the regulation is consistent with this Nation’s historical tradition of firearm regulation. Only if a firearm regulation is consistent with this Nation’s historical tradition may a court conclude that the individual’s conduct falls outside the Second Amendment’s “unqualified command.”

The court found that Bruen established that the Second Amendment’s right to bear arms established a parallel right to purchase and possess ammunition. Benitez reasoned that such a finding is in line with the US’s tradition surrounding firearm possession. In the decision, Benitez wrote,”[A]ll a plaintiff needs to allege is that by preventing him from buying ammunition, the government’s background check system infringed his right to bear arms.”

California had attempted to defend the law under Bruen by claiming that the state government had an inherent interest in the regulation of ammunition sales. However, court found the state’s reasoning insufficient to meet the Bruen threshold.

The challenged sections of the California Penal Code were also overturned due to a portion of the US Constitution know as the “Dormant” Commerce Clause. The Commerce Clause gives the US federal legislature the power to regulate interstate commerce. The Dormant Commerce Clause is a clause that has been read into the Commerce Clause, which prohibits states from discriminating against out of state commerce. In this case, Benitez found that, by disallowing California residents from purchasing and importing ammunition from other states, the California Penal Code discriminated against out of state ammunition vendors. This regulation left California residents only one option: to purchase ammunition from in state vendors.

California Attorney General Rob Bonta responded to the decision 0n X (formerly Twitter) on Wednesday. In a post, Bonta said, “We will seek an immediate stay of the district court decision, to maintain CA’s life saving, constitutional ammunition laws.”