President Donald Trump said on Tuesday that he would seek a ban on bump stocks, a move he was expected to make, but one that still feels surprising given the president’s far-right politics. There’s just one problem: Trump’s memo could be overturned by the next president, or see its legality entrenched in in court proceedings. Crucially, the measure doesn’t have the staying power of a law passed in Congress.

“Just a few moments ago, I signed a memorandum directing the attorney general to propose regulations to ban that turn legal weapons into machine guns. I expect that these critical regulations will be finalized — Jeff — very soon,” Trump said at the White House, making eye contact with Attorney General Jeff Sessions during his comments.

How a Bump Stock Works

A bump fire stock is attached to the end of of a rifle to turn the semi-automatic into a fully automatic firearm, also known as a machine gun. The difference in how fast these two firearms fire is astronomical — a semi-automatic rifle can fire between 45 and 60 rounds per minute, while an automatic rifle can fire hundreds of rounds each minute.

“The bump stock is an attachment that replaces the butt stock of the rifle,” shooting instructor Frankie McRae told ABC News Australia in October. “Personally I don’t like them because they make it more inaccurate, but it’s a part that’s legal to have on a firearm,, and I’m a Constitutionalist and the Second Amendment says ‘it shall not be infringed,,’ and the word ‘infringed’ means by banning parts on firearms is against the Constitution.”

What’s Next for the Bump Stock Ban?

Trump directed the Justice Department to ban the bump stocks, circumventing a review of them being conducted by the Bureau of Alcohol, Tobacco, Firearms and Explosives. Interestingly, the New York Times reported that the ATF review was ongoing, citing an official with the bureau who made those comments even as Trump was still speaking.

The National Rifle Association called on lawmakers after the Las Vegas shooting in October to consider banning “bump stocks,” a device the shooter outfitted his guns with to rapidly fire round after round with a single pull of the trigger. Armed with his modified weapons, Stephen Paddock killed 58 people attending a music festival in just 10 minutes.

Banning bump stocks received bipartisan support after the Vegas shooting, an extremely rare event when it comes to gun laws. Republican Congressman Carlos Curbelo introduced a bill in the House to ban them. In the Senate, Democrat Dianne Feinstein proposed a bump stock bill as well.

The NRA saw the bills — neither of which has been brought to the floor for a vote — as overreaches:

“The [bills] go beyond banning bump stocks, it could ban things like aftermarket triggers, bolts, or other components,” argued the NRA in a tweet last fall.

Will Bump Stocks Be Banned by Congress?

On Tuesday, Curbelo commented on Twitter that Trump’s order — which can be overturned by the next president — wasn’t enough; that there needs to be a legislative ban:

Even top Republican leaders entertained the possibility of gun control legislation. House Speaker Paul Ryan said he would direct lawmakers to “look into” bump stock restrictions back in October, but Trump’s order seems to mute Ryan’s lip service.

Feinstein said Tuesday she also wants a stronger ban.

Opposition to a Legislative Bump Stock Ban

The right-wing news website the Washington Free Beacon wrote at the time of the proposed bump stock ban that it would go too far.

Instead, in addition to banning bump fire stocks and requiring their surrendering or confiscation, it bans and requires the surrendering or confiscation of any part that increases how quickly a semi-automatic rifle can be fired.