(AP Photo/Rich Pedroncelli,file)

Democrats appear to be close to forcing a vote on a proposal that would ban suspected terrorists from buying guns, with presumptive GOP nominee Donald Trump even signaling possible openness to some kind of measure along these lines. But as I noted earlier, the proposal has stirred serious concerns from civil libertarians, who worry that it could end up depriving people of their Second Amendment right to gun ownership without due process.

I’ve got some more detail on how this proposal would work from the office of its chief sponsor, Senator Dianne Feinstein of California.

The crux of the proposal is that it would not automatically result in anyone being denied the right to buy a firearm based on suspicion of terror-related behavior. Rather, it would give the Attorney General the discretion to block a sale to a given individual suspected of involvement of some kind in terrorism.

The amendment’s text specifies that the Attorney General “may deny the transfer of a firearm” if he determines that the recipient “represents a threat to public safety” on the basis of a “reasonable suspicion” that he or she has “engaged in conduct” that constitutes aiding or preparing for “terrorism,” or providing “material support” for it.

The amendment also says that when anyone tries to buy a gun who has been investigated in the last five years for “conduct related to a Federal crime of terrorism,” the Attorney General’s office “shall be promptly notified of the attempted purchase.”

Feinstein’s office provides me with the following clarification:

The senator’s proposal would ensure that anyone who has been the subject of a federal terrorism investigation in the past five years would be automatically flagged within the existing background check system for further review by the Justice Department. It does not require the attorney general to block a gun sale to those individuals. It merely refers them for additional scrutiny.

This new proposal doesn’t actually have anything to do with any currently existing “Terrorist Watchlist,” Feinstein’s office says, despite widespread reporting to the contrary. Rather, anyone who has been targeted by a federal terror probe in the past five years would be marked as someone who raises a red flag when he or she tries to buy a gun. At that point, the Attorney General would have the power to block it, a decision that would presumably be based on what the FBI knew about that person.

Sen. Pat Toomey (R-Penn.) said on June 15, as Democrats filibustered in hopes of enacting gun control legislation, that he wants to work with senators on both sides of the aisle to close the so-called "terrorist loophole" by restricting gun sales to people named on the terrorist watch list. (C-SPAN)

To be clear, it is likely, based on the text of the amendment, that anyone who meets the standard for getting flagged this way might also be on the Terrorist Watchlist. That is not a controlling requirement, however.

But what happens if someone feels that he or she has been unfairly blocked from buying a gun, perhaps after getting cleared of suspicion, or for some other reason? There is an appeals process of sorts, Feinstein’s office says:

Under the amendment, an individual denied a gun would have the ability to learn the reason for the denial. That individual could then appeal the decision administratively with the Justice Department. If necessary, the individual could also sue the Justice Department. This appeals process mirrors the appeals process for other individuals who believe they have wrongly been denied guns.

Feinstein’s office further clarifies that anyone who “appeals the decision administratively with the Justice Department” would do so through the existing appeals process that is already a part of the National Instant Criminal Background Check System, which is operated by the FBI and currently runs background checks on guns sold by federally licensed firearms dealers. (A separate Democratic proposal, which is also likely to get a new vote, would expand this system of checks to cover private sales, closing a loophole that advocates say is enabling criminals and prohibited purchasers from getting guns).

That NICS appeals process is detailed right here. The current NICS background check system enables the FBI to block gun purchases to people who are currently prohibited by federal law from gun ownership: Felons, people convicted of a violent crime, drug users and convicts, people who have been “adjudicated” to be “mental defectives,” illegal aliens, and so forth. All those people can appeal it to the NICS if they believe they have been wrongly blocked from buying a gun. If that appeal is denied, then they are essentially out of options.

Basically, the new proposal would expand those categories to include people who have been investigated for terrorism in the last five years. But this is different, in two key ways. It’s a bit more discretionary: This would allow the Attorney General to block sales to those people. At the same time, though, this would appear to be a murkier category than the above groups who have already been prohibited from buying a gun under federal law: This new group is flagged by virtue of having been investigated for terror in the last five years.

Someone like Orlando shooter Omar Mateen, who was probed by the FBI twice but determined not to be a threat, could now be blocked. Many others could, too. But if I understand this correctly, such a decision would be on the basis of whatever the FBI had determined about any such person, even if the investigation into that person had produced no conviction.

People blocked in this fashion, too, can appeal it to the NICS. But if their appeals are denied, it’s unclear that they’d have any recourse at that point, beyond suing the Attorney General.

And so, even if this proposal is not directly related to the Terrorist Watchlist, anyone who sees that list as problematic will also see this new proposal as problematic. That’s because the Attorney General decides whether you can be blocked from buying a gun — the discretion to do this is triggered by the mere fact of having been investigated for terror in the past five years — and the FBI decides whether your appeal of any such decision will be granted. And there’s no meaningful recourse to any legal process outside of that beyond suing, at least that I can see.