Politico's Democratic presidential debate “Wrongometer” criticized comments from Sen. Bernie Sanders during the Democratic presidential debate by relying on a misleading definition to conclude that the “gun show loophole” -- a decades-old policy term referring to gun sales without a background check that occur at gun shows -- “doesn't actually exist.”

Indeed, Politico itself has repeatedly used the term “gun show loophole.”

During CNN's October 13 debate, Sen. Bernie Sanders (I-VT) said the United States has to “do away with this gun show loophole.”

Politico purported to fact check this statement, concluding, “Sorry, Bernie: The 'gun show loophole' doesn't exist.” According to Politico the “gun show loophole” does not exist because “there's nothing in particular about gun shows that allows otherwise illegal gun sales to occur”:

When Bernie Sanders mentioned closing the so-called “gun show” loophole--one of the most widely supported gun-control measures on the left. But there's one problem: the “gun show” loophole doesn't actually exist.

There's nothing in particular about gun shows that allows otherwise illegal gun sales to occur. Sanders instead is referring to an exclusion in the gun laws that does not require a background check in a private sale. It doesn't matter if that sale is at the seller's home or at a gun show, a background check is not legally required.

But the occurrence of “otherwise illegal gun sales” is not the definition of the “gun show loophole.” Instead the term has always referred to the sale of firearms without a background check by so-called “private sellers” at gun shows.

The term “gun show loophole” came to widespread use in the wake of the 1999 Columbine High School massacre. All four guns used in that mass shooting passed through a local gun show in private sales that did not include a background check. (Today the term “private sales loophole” is often used because it encompasses sales without a background check at gun shows, in-person sales outside of gun shows, and sales through other venues such as the Internet.)

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has estimated that between 25 and 50 percent of sales at gun shows are conducted by private sellers without a background check, while the rest are conducted with a background check by licensed gun dealers in possession of a Federal Firearms License (FFL). Under federal law individuals who are “engaged in the business” of selling firearms are required to obtain an FFL and perform checks on customers, while individuals who make “occasional” sales are not. Because these terms are vaguely defined, unscrupulous “private sellers” can exploit the language of the law to operate unlicensed pseudo-businesses.

If the loophole did not exist, several states would not have moved to close it, but that is exactly what has happened. According to the Law Center to Prevent Gun Violence, Connecticut, Colorado, Illinois and New York all “have laws expressly addressing background checks at gun shows, although broader laws also apply.” Other states have more expansive laws requiring background checks for all firearm transfers that encompass private sales at gun shows.

There is good reason to believe that the “gun show loophole” is exploited by individuals who would not be able to pass a background check. A 2011 undercover investigation of seven gun shows in three states by the City of New York found that 19 out of 30 private sellers agreed to a sale where the buyer said he probably couldn't pass a background check. The loophole is also ripe for abuse by narco-terrorists, illegal gun traffickers and other dangerous individuals.

Politico's purported fact check of Sanders' statement is also nonsensical because the outlet itself has used the term “gun show loophole” to refer to private sales at gun shows. A 2013 Politico article used the term the same way Sanders did in the debate:

“The 'private sale' loophole is the gaping hole in our federal gun laws which allows anyone who is not a federally licensed gun dealer to sell a gun without a background check -- no questions asked,” said Jonathan E. Lowy, legal action director of The Brady Campaign.

It's also referred to as the gun-show loophole, because it can allow collectors to sell each other guns during gun shows, said John Lott, the former chief economist of the U.S. Sentencing Commission. Some states have already passed laws to include running background checks on privatized gun sales, but there's no federal law.

In December 2012, Politico used the term “gun show loophole” in a section header to describe sales without background checks in an article that was billed as “POLITICO's look at the top policy proposals circulating in the wake of the” Sandy Hook Elementary School mass shooting (emphasis original):

Closing the gun show loophole

Requiring every person-to-person gun sale to be subject to a background check -- long a favorite talking point of the gun control crowd -- is perhaps the easiest for lawmakers to support but the most logistically difficult measure to achieve. The 1993 Brady law requires background checks for guns purchased by licensed dealers, but it does not address private sales.

After the 2007 mass shooting at Virginia Tech, Politico again used the term “gun show loophole” to describe private sales at gun shows:

Pennsylvania's experience closely mirrors what happened in Colorado after the 1999 Columbine shootings, in which 12 students and a teacher were killed. Lawmakers failed to close the “gun show loophole” by passing a law requiring background checks at gun shows. Instead, voters petitioned it onto the ballot in 2000, and it passed with more than 70 percent of the vote.

Oregon voters also had to take matters into their own hands after lawmakers failed to close a gun show loophole after a school shooting in 1998. The ballot measure closing the loophole passed with more than 60 percent of the vote.