A federal judge overturned California's three-decade-old ban on assault weapons on Friday, ruling that it violates the constitutional right to possess arms.

San Diego District Judge Roger Benitez called the ban a "failed experiment," adding that California's definition of military-style weapons unlawfully deprives law-abiding citizens of arms allowed in most other states and by the Supreme Court.

Benitez said Americans have the right to own semi-automatic rifles.

"Like the Swiss Army knife, the popular AR-15 rifle is a perfect combination of home defense weapon and homeland defense equipment. Good for both home and battle," the judge said in his ruling's introduction.

"Guns and ammunition in the hands of criminals, tyrants and terrorists are dangerous; guns in the hands of law-abiding responsible citizens are better," he added in the 94-page decision.

The ruling comes as gun-related homicides surge across the US, which President Joe Biden has called an "epidemic."

California governor condemns decision

Governor Gavin Newsom slammed the ruling, calling it "a direct threat to public safety and the lives of innocent Californians, period." Newsom pledged to challenge the decision.

"We're not backing down from this fight, and we'll continue pushing for common sense gun laws that will save lives," he said in a statement.

State Attorney General Rob Bonta has 30 days to appeal.

US mass shootings on rise

California banned the sale of assault weapons in 1989. Plaintiffs James Miller, a California resident, and the San Diego County Gun Owners, a political organized, challenged the law in a suit filed in 2019 against California's attorney general.

The state attorney general's office have said assault weapons as defined by the law are more dangerous than other firearms and are disproportionately used in crimes, mass shootings and against law enforcement, with more resulting fatalities.

State officials said overturning the ban would also mean allowing not only assault rifles, but things like assault shotguns and assault pistols.

The ruling comes just over a week after a California transit employee killed nine co-workers before taking his own life, the latest in a spate of deadly US mass shootings.

Following a search of the shooter's home, police uncovered 12 guns, around 22,000 rounds of ammunition and suspected Molotov cocktails.

mvb/rc (AP, AFP)