Anger as judge compares AR-15s to Swiss Army knives while striking down California assault weapon ban

A federal judge has struck down California's ban on assault weapons, ruling it unconstitutional and offering a defence of the AR-15 in his ruling which angered family members of those killed by such weapons.

Judge Roger T Benitez, who has favoured gun rights organisations in previous rulings, described the rifle – which has been the go-to gun for many of the nation's deadliest mass shooters – as the pinnacle of home self-defence.

"Like the Swiss Army Knife, the popular AR-15 rifle is a perfect combination of home defence weapon and homeland defence equipment," he wrote in his decision on Friday. "Yet, the State of California makes it a crime to have an AR15 type rifle. Therefore, this Court declares the California statutes to be unconstitutional."

He claimed the AR-15 should be legally protected for its "militia readiness."

The state's Democratic Governor Gavin Newsom was infuriated by the ruling and suggested the judge's description of the weapon invalidated the soundness of his ruling.

“The fact that this judge compared the AR-15 — a weapon of war that’s used on the battlefield — to a Swiss Army knife completely undermines the credibility of this decision and is a slap in the face to the families who’ve lost loved ones to this weapon,” he said.

The state has already announced its intentions to appeal the ruling.

"Today's decision is fundamentally flawed, and we will be appealing it," Attorney General Rob Bonta said. "There is no sound basis in law, fact, or common sense for equating assault rifles with Swiss Army knives."

California first prohibited assault weapons in 1989, and expanded its definition to include more firearms in later years.

The Las Vegas shooter, Steven Paddock, had 14 AR-15s and eight AR-10-type rifles that he used to carry out the worst mass shooting in modern American history.

Armed with the weapons, bump stocks – an easy modification that boosts the weapons' rate of fire – and ammunition, Paddock managed to kill 60 people and wound 411.

Fred Guttenberg, whose daughter was killed in the Parkland shooting, has become a vociferous gun control advocate and issued a strong condemnation of the ruling.

“My daughter’s in a cemetery…because a Swiss Army knife was not used. Because it was an AR-15,” he said.

He accused the judge of being an “activist” and said his opinion was written using the same language the gun lobby uses to defend firearms.

Social media users battled over the ruling, with many questioning the judge's rationale for overturning the ban on Gun Violence Awareness Day.

Mr Benitez stayed his own permanent injunction against the state's weapons ban for 30 days, which will allow the attorney general time to appeal the ruling.