The U.S. Bureau of Alcohol, Tobacco, Firearms, and Explosives' (ATF) final rule banning bump stocks went into effect in March 2019.
"This is a horrible decision that will undoubtedly result in more gun deaths," Congressional Progressive Caucus Chair Pramila Jayapal (D-Wash.) said on social media. "The bump stock ban had bipartisan support following the deadliest mass shooting in U.S. history—this ruling is another example of SCOTUS legislating from the bench, against the will of the people."
Congresswoman Rashida Tlaib (D-Mich.) lamented that "gun violence is already the leading cause of death for children and teens in our country. This will make mass shootings deadlier."
"SCOTUS has blood on its hands," she added. "This unhinged Supreme Court needs to stop legislating from the bench."
Rep. Maxwell Frost (D-Fla.) decried what he called "a disgraceful decision by the Corrupt Supreme Court that will result in the death of more Americans, especially children."
"Congress must act swiftly to pass a bump stocks ban," he added. "Time to organize."
Gun control activists also condemned the ruling.
"The majority of justices today sided with the gun lobby instead of the safety of the American people. This is a shameful decision," said Giffords Law Center litigation director Esther Sanchez-Gomez. "Congress must act to undo the damage and make clear that bump stocks, and all automatic conversion devices, are illegal under federal law."
The group Everytown said: "Bump stocks were designed to skirt the law and mimic automatic fire. There is no reason anyone should be able to easily convert a weapon to fire 800 rounds per minute. Machine guns don't belong in our communities."
"The Supreme Court has put countless lives in danger," the group added. "Congress can and should right this deadly wrong by passing bipartisan legislation to ban bump stocks that has already been introduced in the House and Senate."
Stasha Rhodes, campaign director at the Supreme Court reform group United for Democracy, said in a statement that "today's ruling out of the Supreme Court is reckless and dangerous."
"In Las Vegas and communities across the country, we've seen how bump stocks can turn community gatherings into tragic, waking nightmares. That's why even the Trump administration banned them in 2017," she continued. "But this morning, the MAGA justices on the Supreme Court showed us the full extent of their radical, right-wing vision on firearms: machine guns everywhere."
"Our communities deserve the freedom to live safely in their communities," Rhodes added. "They deserve to have elected representatives, not politicians in robes, making policy decisions that impact their day-to-day lives."
Bump stocks are fitted in place of a rifle's butt stock and allow a semiautomatic weapon to fire multiple rounds with a single pull of the trigger by harnessing the gun's recoil energy. They greatly increase a gun's rate of fire at the expense of its accuracy, making semiautomatic weapons behave similar to machine guns.
Congress outlawed machine guns under the National Firearms Act of 1934, which defined such firearms as "any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger." The Gun Control Act of 1968 expanded this definition to include accessories that could be used to convert a weapon into a machine gun.
"A bump stock does not convert a semiautomatic rifle into a machine gun any more than a shooter with a lightning-fast trigger finger does," Justice Clarence Thomas wrote for the majority in Garland v. Cargill. "Even with a bump stock, a semiautomatic rifle will fire only one shot for every 'function of the trigger.'"
Writing for the dissenting liberal members of the court, Justice Sonia Sotomayor said: "Today, the court puts bump stocks back in civilian hands. To do so, it casts aside Congress' definition of 'machine gun' and seizes upon one that is inconsistent with the ordinary meaning of the statutory text and unsupported by context or purpose."
"Today's decision to reject that ordinary understanding will have deadly consequences," she added. "The majority's artificially narrow definition hamstrings the government's efforts to keep machine guns from gunmen like the Las Vegas shooter."
Case plaintiff Michael Cargill, a Texas gun store owner, celebrated the ruling.
"Breaking news, I did it," Cargill said in a video posted on social media. "I beat them in the United States Supreme Court."
"I stood and fought, and because of this, the bump stock case is gonna be the case that saves everything," he continued. "It's gonna stop the ATF from coming after your brace, the triggers, all different parts and pieces that they're trying to ban."
"As always, more guns equals less crime," Cargill added. "You go out there and you buy yourself a gun. Better yet, get yourself a bump stock."