Trump blames Obama for legalizing bump stocks in a tweet. Is he right?

William Cummings | USA TODAY

In announcing the Justice Department's proposal to ban bump stocks in a tweet on Friday, President Trump blamed his predecessor for permitting the devices to be sold.

"Obama Administration legalized bump stocks," the president tweeted, "BAD IDEA. As I promised, today the Department of Justice will issue the rule banning BUMP STOCKS with a mandated comment period. We will BAN all devices that turn legal weapons into illegal machine guns."

Obama Administration legalized bump stocks. BAD IDEA. As I promised, today the Department of Justice will issue the rule banning BUMP STOCKS with a mandated comment period. We will BAN all devices that turn legal weapons into illegal machine guns. — Donald J. Trump (@realDonaldTrump) March 23, 2018

Attorney General Jeff Sessions announced a rule change that expanded the definition of machine gun in federal law to include "bump stock-type devices."

Bump stocks, which use the recoil of a semi-automatic firearm to simulate automatic fire, came into the national spotlight after a gunman in Las Vegas used the devices in a massacre that killed 58 people and injured more than 500.

"After the senseless attack in Las Vegas, this proposed rule is a critical step in our effort to reduce the threat of gun violence that is in keeping with the Constitution and the laws passed by Congress," Sessions said in a statement Friday.

Trump proposes ban of rapid-fire gun devices President Donald Trump says he's signed a memo directing the Justice Department to propose regulations to "ban all devices" like bump stocks used in last year's Las Vegas massacre. (Feb. 20)

So, is Trump correct in his assertion that former president Barack Obama "legalized bump stocks?"

The answer is: sort of.

More: 'Bump stocks' may be new to you, but federal officials have grappled with them for years

In 2010 the Bureau of Alcohol, Tobacco, Firearms and Explosives determined that because bump stocks don't have any moving parts, they are a "firearm part" and could not be regulated as a firearm under existing gun laws. The ATF reached a similar conclusion in 2012.

Adam Winkler, a constitutional law professor at the University of California, Los Angeles, told PolitiFact that it is accurate to say the Obama administration approved the sale of bumps stocks.

"Not because they liked it, but because the law did not permit them to prohibit it," Winkler told the fact-checking organization, which explored the issue after the National Rifle Association said in October that the Obama administration approved bump stocks on two occasions.

Rick Vasquez, a former ATF official who took part in the decision to approve bump stocks, told Politifact that to blame the administration implies that Obama or his then-attorney general Eric Holder were involved in the determination.

"We never had any political people come down to our office saying we must or must not approve," Vasquez said.

Trump is partly wrong about machine guns being illegal. Congress banned the sale of new machine guns for civilian use in 1986, but possession of older automatic weapons is still allowed with a special permit.

Earlier this month, Sessions sent the changed machine gun definition to the Office of Management and Budget, continuing a process that began Feb. 20 when Trump signed an executive order directing Sessions to get the ball rolling on a bump stock ban.

The proposal will undergo a 90-day review period before becoming final. After that, if the rule is made final, bump stock owners will be required to surrender or destroy the devices.