A California appeals court ruled on Thursday that a state law requiring people to undergo background checks each time they purchase ammunition is unconstitutional.

In a 2-1 decision, the 9th U.S. Circuit Court of Appeals ruled that the law “meaningfully constrains” Second Amendment rights, marking a blow to California’s gun control regulations, which are viewed as some of the toughest in the nation. Voters initially approved the measure via referendum in 2016.