(CNN) Former Rep. Beto O'Rourke of Texas has made his position on assault weapons crystal clear. "Hell, yes, we're going to take your AR-15, your AK-47," O'Rourke said during Thursday's Democratic presidential debate. "We're not going to allow it to be used against our fellow Americans anymore."

To accomplish this, O'Rourke has proposed a mandatory confiscation of these guns whereby individuals would be compensated for their firearms.

Beyond the thorny politics of this proposal, it raises clear legal and logistical questions, including whether a president has the authority to confiscate people's guns.

Facts First: A president could not issue a blanket confiscation of so-called assault weapons, but they could work with Congress to pass such a law. Constitutionally speaking, that law would likely run into some significant legal trouble.

First, some basic facts. The National Rifle Association has estimated that there are somewhere between 8.5 million and 15 million assault rifles in the US, the organization told McClatchy in 2018. That's about 2% to 4% of all the estimated guns in the US, but it's unclear how many guns would ultimately fall under an assault weapons confiscation.

Part of that has to do with the fuzzy definition of what qualifies as an assault weapon, which can sometimes be based on cosmetic features like a folding stock or an additional handgrip on a rifle.

In 1994, assault weapons were banned from being manufactured but the law did not call for the confiscation of those already in private ownership. That assault weapons ban expired in 2004 and was not renewed under the George W. Bush administration.

O'Rourke's plan, however, not only would include a ban on all sales of so-called assault weapons but also would require owners to sell these guns to the Bureau of Alcohol, Tobacco, Firearms and Explosives, something the US government has never done before.

Because of precedent set by the Supreme Court, the widespread use and popularity of these guns would almost certainly present legal trouble for O'Rourke's proposal.

In the 2008 case District of Columbia v. Heller, the Supreme Court ruled on whether a ban on handgun possession in the home violated the Second Amendment. It found that it did, holding that the Second Amendment protects guns that are "in common use" and prohibits " 'dangerous and unusual weapons.' "

In response to questions about the constitutionality of his proposal, O'Rourke's campaign told CNN that the confiscation of AR-15-style weapons would be legal, and cited Justice Antonin Scalia's opinion from Heller, that the regulation of "dangerous [and] unusual weapons" does not violate the Second Amendment.

However, Scalia's opinion states that the Second Amendment protects guns in "common use." Given their prevalence, these assault weapons could fall under the definition of being "in common use," and therefore be protected by the Second Amendment.

At least one expert believes that common use interpretation would carry the day. "There's no dispute that these guns meet that definition," Dave Kopel, gun rights scholar and research director of the Independence Institute, told CNN.