A federal judge late Friday overturned California’s longtime ban on assault weapons, saying the state’s law was unconstitutional and that prohibiting such firearms for decades was “a failed experiment.”

In a 94-page ruling, U.S. District Judge Roger Benitez of the Southern District of California said that sections of the state ban in place since 1989 regarding military-style rifles violate the Second Amendment. Judge Benitez characterized the assault weapons Californians are barred from using as not “bazookas, howitzers or machine guns” but rather “fairly ordinary, popular, modern rifles.”

The judge then compared an AR-15 to a Swiss Army knife.

“Like the Swiss Army Knife, the popular AR-15 rifle is a perfect combination of home defense weapon and homeland defense equipment,” Judge Benitez said in the ruling.

In addition to issuing a permanent injunction Friday, Judge Benitez granted a request from California Attorney General Rob Bonta for a 30-day stay of the ruling, which will bring about an appeal from the state.

“Today’s decision is fundamentally flawed,” Mr. Bonta said in a news release. “There is no sound basis in law, fact, or common sense for equating assault rifles with Swiss Army knives — especially on Gun Violence Awareness Day and after the recent shootings in our own California communities.”

Judge Benitez’s ruling comes as the nation continues to grapple with gun violence and pushes from lawmakers to ban assault weapons. After pushing for a ban on assault weapons and high-capacity ammunition magazines, President Joe Biden announced in April a series of executive actions to help curb gun violence. Last month, the Justice Department released a proposed rule that would put new restrictions on “ghost guns” — kits that allow buyers to assemble firearms without a serial number.

Though the actions were part of the president’s first substantive response to mass shootings, he and lawmakers nationwide have faced many of the same cultural and political divisions that have stymied efforts to pass assault weapons bans.

Legal experts told The Washington Post that Judge Benitez’s ruling, which compares assault weapons to knives in the first three pages, is similar to language used by gun-rights advocates in arguing for the popularity of the firearms in the United States.

“When I read something like this — ‘What about knives?’— my instinct is to say that the Las Vegas shooter didn’t use knives to rain down fire on a concert,” said Darrell Miller, a law professor and co-director of Duke University’s Center for Firearms Law.

The California ban has been revised multiple times over the past three decades. The state has argued that assault weapons restrictions have also previously been upheld by several federal district and appeals courts.

The judge’s decision stems from a lawsuit filed in 2019 by a state resident and a political action committee for gun owners. The lawsuit against California said the state is “one of only a small handful of states to ban many of the most popular semiautomatic firearms in the nation because they possess one or more common characteristics, such as pistol grips and threaded barrels” that are frequently used with detachable ammunition magazines.

The AR-15, a lightweight, customizable version of the military’s M-16, soared in popularity after a 10-year federal ban on assault weapons expired in 2004. It has also been slammed by lawmakers and gun-control advocates for its use in mass shootings.

The state previously argued in a court filing that a spike in sales in the past year of more than 1.16 million other types of pistols, rifles and shotguns “has not prevented law-abiding citizens in the state from acquiring a range of firearms for lawful purposes, including self-defense.”

Judge Benitez pushed back on that notion in his ruling. Despite the ban, there are an estimated 185,569 assault weapons registered with the state, the judge said.

“This is an average case about average guns used in average ways for average purposes,” Judge Benitez wrote. “One is to be forgiven if one is persuaded by news media and others that the nation is awash with murderous AR-15 assault rifles. The facts, however, do not support this hyperbole, and facts matter.”

The judge made another mention of knives in his ruling, claiming that “murder by knife occurs seven times more often than murder by rifle” in California.

It’s not the first time Judge Benitez has ruled in favor of gun rights since he was appointed by President George W. Bush and confirmed by the Senate in 2004. Judge Benitez has previously ruled that the state’s ban on high-capacity magazines was unconstitutional and also struck down the restriction on remote purchases of gun ammunition. The state is appealing both of those decisions.

Mr. Miller said to The Post that Judge Benitez, citing how Fidel Castro’s toppling of the country’s previous regime was evidence of how these kinds of firearms can be used against well-equipped armies, sounded as if the judge was making an argument for assault weapons “in case we need to topple the American government.”

While it’s still unclear how the case could play out in appeal, if Judge Benitez’s ruling did indeed make it to the U.S. Supreme Court, Mr. Miller said there is “far more of an appetite” for the high court to take on Second Amendment cases.

John Donohue III, an expert on gun violence and regulation at Stanford Law School, said much of the litigation to overturn gun control measures in the United States focuses on California, given the state’s strict policies. The goal for the gun lobby, Mr. Donohue said, is to “get these cases up to the Supreme Court where they think they can win.”

The ruling was met with pushback from Democrats and gun control advocates. California Gov. Gavin Newsom lashed out at the judge’s ruling in a late-night tweet, saying that Judge Benitez comparing an AR-15 to a Swiss Army knife was a “disgusting slap in the face to those who have lost loved ones to gun violence.”

“This is a direct threat to public safety and innocent Californians,” Mr. Newsom said. “We won’t stand for it.”

California Assembly Speaker Anthony Rendon told The Post that “all Californians are at greater risk as a result of this decision.” House Speaker Nancy Pelosi, D-Calif., on Saturday said the ruling “poses a clear & serious threat to public safety & innocent lives” if it is upheld in court. “House-passed gun violence prevention bills must be enacted now,” she tweeted.

The news out of California reverberated across the nation over the weekend. Fred Guttenberg, whose 14-year-old daughter Jaime was killed in the 2018 mass shooting in Parkland, Fla., denounced the judge for using “the exact language of the gun lobby” in his ruling. A version of the AR-15 was used to kill 17 people at Marjory Stoneman Douglas High School.

“My daughter’s in a cemetery ... because a Swiss Army knife was not used. Because it was an AR-15,” Mr. Guttenberg, a gun safety activist, told CNN. “If a Swiss Army knife was used, my daughter and most of those other kids and adults would be alive today.”

The Washington Post’s Rachel Siegel contributed to this report.

First Published: June 5, 2021, 7:53 p.m.