A federal judge has blocked a California law requiring background checks for ammunition purchases, stating the regulation violates the Second Amendment.

In a strongly worded critique, Judge Roger Benitez in San Diego on Thursday preliminarily enjoined California from enforcing the background check provision of Proposition 63 as it is litigated, stating the new gun control measure is “onerous,” “convoluted” and “constitutionally defective.”

“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,” he wrote in his 120-page ruling.

The provision was one of several included in Proposition 63, which a majority of Californian voters approved in 2016.

The plaintiffs — the California Rifle and Pistol Association, Olympic skeet shooter Kim Rhode and other gun enthusiasts — filed a motion for a preliminary injunction against the provision after it was rolled out in July 2018, saying it placed “an unconstitutionally excessive burden on law-abiding gun owners with little to no law enforcement value.”

Chuck Michel, president and general counsel of the CRPA, called the ruling “a devastating blow to the anti-gun-owner advocates who falsely pushed Prop 63 in the name of safety.”

“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,” Michel said in a statement. “The court found that the flimsy reasons offered by the government to justify these constitutional infringements were woefully inadequate.”

Non-profit Brady: United Against Gun Violence chastised the court for its decision as “patently wrong.”

“An unelected judge has — temporarily — deprived Californians of an important public safety law that they want and need, claiming an unprecedented, radical revision of the Second Amendment that is contrary to what the Framers intended, and to basic principles of democracy,” Brady President Kris Brown said in a statement, vowing to support the law on appeal.