The U.S. Supreme Court ruled today to overturn a ban on bump stocks, a device that turns a semiautomatic rifle into a gun capable of firing 400-800 rounds a minute. The ban was imposed in 2018 by the Trump administration after the massacre of 60 people at a music festival in Las Vegas, the deadliest mass shooting in U.S. history. The shooter fired from a high floor in a hotel overlooking the festival; he used a bump stock.

The 6-3 decision was written by Justice Clarence Thomas, who ruled that a bump stock does not convert a semiautomatic rifle into a machine gun. A 1986 law prohibits civilians from owning machine guns.

The question was whether the bump stock could fire multiple rounds with a single pull of the trigger or required multiple pulls.

The National Rifle Association must be celebrating. Responsible gun owners are not.