GRAND RAPIDS, MI – The Trump administration defended the ban on bump stocks, saying the device, used on semi-automatic firearms, allows it to fire like a machine gun.

The defense came in response to a gun-rights group’s lawsuit filed in U.S. District Court in Grand Rapids alleging Second Amendment violations for making the bump stocks illegal.

A gunman used bump stocks when he opened fire from a Las Vegas hotel onto a crowd at a country music concert, killing 58 and injuring about 500 in the deadliest mass shooting in modern U.S. history.

The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives, or ATF, had earlier determined that bump stocks were not considered machine guns – thus, not illegal.

“After the Las Vegas shooting, members of Congress and the public asked ATF to re-examine its past classification decisions for bump stocks to determine whether those decisions had been correct. In addition, President Trump instructed the Attorney General to ‘dedicate all available resources to … propose for notice and comment a rule banning all devices that turn legal weapons into machine guns,” U.S. Department of Justice attorney Eric Soskin wrote in court documents.

The filing in U.S. District Court came in response to a lawsuit and request for preliminary injunction filed by Gun Owners of America Inc. and others against the Department of Justice, ATF and government officials.

The request for a preliminary injunction said the ATF has concluded for over a decade “that bump fire stocks do not meet the federal statutory definition as to what constitutes a machine gun, and thus are outside the purview of the (ATF) to ban,” attorney Kerry Morgan wrote.

“Nevertheless, defendants have now departed from their past adherence to the statutory definition, switched their bump stock ‘classification’ 180 degrees, and abandoned prior administrative rulings, all for one simple reason – earlier (last year), President Trump ordered that bump stocks be banned.”

Under the new regulation, guns owners would have to destroy or turn in bump stocks by March 29. Bump stocks would fall under prohibitions of possessing machine guns.

The gun owner’s organization said the rule change is “arbitrary and capricious. It is arbitrary, because it is founded on political pressure and demonstrably false factual assumptions, rather than on fixed rules, procedures, or law.”

It contends that the bump stock helps a shooter fire quicker, but not automatically with a single trigger pull like a machine gun.

Gun Owners of America say there are 520,000 bump stocks in the United States. They contend that the president and ATF do not have the power to change the legal definition of a machine gun to now include bump stocks.

A bump stock replaces the standard stock on a gun. The ATF says it “harnesses and directs the firearm’s recoil energy to slide the firearm back and forth so that the trigger automatically re-engages by ‘bumping’ the shooter’s stationary finger.”

Morgan, the attorney for Gun Owners of America, said: “That statement is patently false to the point of being absurd.”

Morgan said that bump stocks are firearm accessories that the government cannot regulate. He said firearms with bump stocks still require a trigger pull for each shot rather than a single pull for automatic firing.

“The fact that Congress did not ‘clearly exclude’ bump stocks from the statute does not mean bureaucrats are free to ‘expand’ the definition as they see fit,” he wrote documents filed this week.

“Rather, ATF may only interpret the statute as written.”

He said the government alleged - but did not prove - that bump stocks were used in the Las Vegas shootings.

The government’s attorney said that by acting on a presidential instruction, the Department of Justice “has corrected a confusing and erroneous agency interpretation … to the expected benefit of public safety.

Here is a link in The New York Times demonstrating how a bump stock works.

Erich Pratt, executive director of Gun Owners of America, based in Springfield, Virginia, said the lawsuit was filed in Michigan because it is within the Sixth Circuit Court of Appeals, which he contends is “not only very pro-gun, but also has been more skeptical of illegal government regulatory actions than many other circuits in the country.”

Next month, U.S. District Judge Paul Maloney in Kalamazoo will hear oral arguments on the request for a preliminary injunction.