A federal judge struck down a California law requiring background checks for buying ammunition, and said it violates a citizen's Second Amendment right to bear arms.

U.S. District Judge Roger Benitez in San Diego ruled in favor of the California Rifle & Pistol Association and six-time Olympic medalist skeet shooter Kim Rhode, who asked to halt the background checks and related restrictions on ammo sales. Benitez blocked the ammunition law, calling it "constitutionally defective."

"California's new ammunition background check law misfires, and the Second Amendment rights of California citizens have been gravely injured," Benitez wrote in a 120-page opinion. "In this action, Plaintiffs seek a preliminary injunction enjoining California's onerous and convoluted new laws requiring ammunition purchase background checks and implementing ammunition anti-importation laws."

Benitez argued that background checks hurt legal ammunition buyers while doing very little to prevent criminals from getting their hands on ammo. He noted that the law blocked legitimate ammo sales to law-abiding citizens about 16% of the time.

"Criminals, tyrants, and terrorists don't do background checks," the judge said. "The background check experiment defies common sense while unduly and severely burdening the Second Amendment rights of every responsible, gun-owning citizen desiring to lawfully buy ammunition."

The law had required buyers to pay a $1 fee for each time they bought ammunition, even if they already passed a background check.

California was the first state in the U.S. to institute background checks for ammunition. In 2016, Californians voted for Proposition 63, which required a background check to purchase ammunition and banned possession of high-capacity magazines. The law went into effect on July 1, 2019. Ammo sales skyrocketed 300% in June before the law went into effect.

"This is a devastating blow to the anti-gun-owner advocates who falsely pushed Prop 63 in the name of safety," California Rifle & Pistol Association President Chuck Michel said in a statement. "In truth, red tape and the state's disastrous database errors made it impossible for hundreds of thousands of law-abiding Californians to purchase ammunition for sport or self-defense."

The ruling takes effect immediately. California's state attorney general's office said it is reviewing the decision but did not immediately say if it would appeal the decision.