New Delhi, July 18 -- PHILADELPHIA - For residents of New Jersey who have lived for decades under one of the country's most restrictive gun laws, Thursday's ruling landed without warning. The full 3rd U.S. Circuit Court of Appeals voted 10-5 to strike down the state's ban on AR-15-style semiautomatic rifles and its ten-round magazine limit, holding that both restrictions violate the Second Amendment. The decision arrives just weeks after the Supreme Court overturned Hawaii's gun-permission law in a 6-3 Second Amendment ruling, and it drops New Jersey into a legal dispute that could reach Washington within months.

Writing for the majority in Association of New Jersey Rifle & Pistol Clubs v. Attorney General, U.S. Circuit Judge Arianna Fre...