U.S. President Barack Obama speaks about counter-terrorism and the United States fight against Islamic State during an address to the nation from the Oval Office of the White House in Washington, December 6, 2015. (REUTERS/Saul Loeb/Pool)

Update, June 13: During a speech on Monday, Hillary Clinton reiterated her suggestion that people included on the government's no-fly list should not be allowed to buy firearms. This article originally ran in December, when the idea of barring gun sales to people on the no-fly list was first proposed.

I made a joke on Twitter on Sunday night, which, as is the case with all Twitter jokes, was a mistake.

It came after President Obama's Oval Office address, during which he advocated for excluding people on the government's no-fly list from buying weapons. The joke was this:

The point of the joke -- which I very quickly realized was lost on some, making it a bad joke -- was that the no-fly list is a secret list that uses secret criteria to determine who finds a home on it. So if you link banning guns to the no-fly list, the scenario presented is completely feasible: The government could theoretically add anyone it wants to the no-fly list, even broad categories of people, and thereby prevent them from owning a gun.

Tim Sparapani is now principal of SPQR Strategies but was formerly senior legislative counsel for the American Civil Liberties Union. In that role, he became intimately familiar with the use of the no-fly list -- or, anyway, as familiar as someone from outside of the government can be. Armed with that knowledge, he explained why using it as the basis for much of anything was iffy, much less banning gun purchases.

"The problem with any kind of watch list," Sparapani said, "is that it's always going to be both under- and over-inclusive. It suffers on both accounts. It causes so many problems that it really leads us to question the worth of having a list like this."

An example of under-reporting was easy to come by: The shooters in San Bernardino. It's not clear that there was a way to definitively identify the married couple as being a public risk ahead of time, but it is clear that they weren't identified as such. There will always be people who are not identified in advance, making the list necessarily incomplete.

The San Bernardino attack also demonstrated the risk of over-inclusion. At least one news outlet confused the male shooter -- Syed Rizwan Farook -- with his brother, Syed Raheel Farook. "They have the same name except for the middle name," Sparapani pointed out, meaning that including a "Syed Farook" on the list might block either from flying. (The shooter's brother is a decorated Navy veteran.) There's also the challenge of converting Arabic names into English writing. Consider the former leader of Libya, Muammar Gaddafi. Or Qaddafi. Or Gadhafi. Do you put all three names on the list? Get the letters wrong, and some people will be banned who shouldn't be.

"What it does is makes us feel better, without providing us additional and necessary safety," Sparapani argued.


From an illustrated guide to the no-fly list by the ACLU.

There are a lot of other concerns about how the list is developed, as well. A lawsuit initiated by the ACLU resulted in the government acquiescing to telling people when they are on the list itself. But, as the organization notes, this still fails to offer those included "meaningful notice, evidence and a hearing." Particularly when applied to the ability to own a firearm, many would argue that the no-fly list is a violation of the 5th Amendment, which guarantees the right to due process before people are deprived of life, liberty or property. During the ACLU's lawsuit, the government admitted that people are added to the list speculatively, before they've actually done anything wrong. What's more, the Guardian reported in 2014 that the list might be used by law enforcement as a pressure point against possible informants.

The list is itself almost necessarily a slippery slope. "There's very little incentive for any particular government official to narrow the list," Sparapani said. "It's much easier to put more and more names on it." The overlap of politics and terror fears makes officials err on the side of caution. "If the list really does need to be in the hundreds of thousands" -- as it appears to be -- "we've got much bigger problems than if people should be able to get on airplanes," he said.

And then, of course, there's the other question.

"Who are these people who are so dangerous that we can't let them on planes, but we haven't gone out and arrested them?" Sparapani asked. "At what point do we actually take action against them if they're under what we think of as passive surveillance? ... If they're too dangerous to be put on a plane but not too dangerous for us to arrest them, what exactly is this list about?"

Asked another way: Who is too dangerous to be on a plane but not dangerous enough to walk around in public -- and should that person be denied the right to own a firearm because they land somewhere in that gray space? President Obama's goal was not really to keep the guns out of the hands of possible terrorists, in part because the overlap of the no-fly list and possible terrorists looks more like a Venn diagram than a circle. It was, instead, part of his effort to limit the availability of guns in general, using the no-fly list as a tool.

Which could almost be funny if you took that idea to its extreme.

Speaking in Cleveland, Ohio, Democratic presidential candidate Hillary Clinton called for unity in the wake of the tragic shooting in Orlando. Here are key moments from that speech. (Reuters/Associated Press)