Nine judges of the American Supreme Court debated the legality of “bump stocks” The device increases the rate of fire of semi-automatic rifles, transforming them de facto into machine guns. These accessories make it possible to “empty a 100-round magazine like those used in the Las Vegas massacre in approximately 10 seconds,” a lawyer told the judges.
The debates, which lasted more than two hours, focused on the technical definition of a machine gun in the 1934 law, at the time of Prohibition.