The office of Attorney General Rob Bonta of California, the case’s defendant, said it was reviewing the decision.
“California will continue to take all necessary steps to prevent and reduce gun violence,” it said in a statement. “We remain committed to defending California’s common-sense gun laws, which save lives and make our communities safer.”
The court did uphold a provision in state law requiring adults under 21 who are not serving in the military or in law enforcement to obtain a hunting license to buy shotguns or rifles. That requirement, the judges wrote, amounted to “sensible firearm control” measures, and was therefore constitutional.
Judge Nelson and Judge Kenneth K. Lee, who were both appointed by President Donald J. Trump, formed the majority opinion; dissenting was Judge Sidney H. Stein, a U.S. District Court judge who was appointed by President Bill Clinton and is sitting by designation on the Court of Appeals.
The semiautomatic ban was part of an array of restrictions on gun ownership that Democrats in California recently passed in response to a rise in gun violence. Leaders are concerned about the illegal trafficking of weapons from surrounding states and the increased supply of homemade weapons, known as “ghost guns.”