PolitiFact rated Republican claims to be "false" or "pants on fire" three times more often than it rated Democratic claims that way this year, according to a new study by the Center for Media and Public Affairs at George Mason University. So: Does the GOP lie more? Is PolitiFact biased? Or do GOP liars — like fact-checking "dream" Michele Bachmann — get more attention?

The Pulitzer prize-winning PolitiFact is run by the Tampa Bay Times, and its reporters and editors sort politicians' claims into one of six categories: true, mostly true, half true, mostly false, false, and pants on fire — the last having an element of the "ridiculous." You can see how those ratings break down for both parties in the pie charts at right. A majority of Democratic claims were rated true; a majority of Republican claims were rated false. CMPA points out that PolitiFact found more Republican lies even in May — though there are three agency scandals facing the Obama administration: over the IRS targeting conservative groups, over the State Department's talking points about Benghazi, and over the Justice Department's investigation into leakers. This month, 60 percent of Republican claims have been rated as lies, while 29 percent of Democratic claims have been.

Why is that? It's possible the fact-checkers are intentionally or unintentionally letting some bias show through. Whether or not that's true, the state of each party right now most certainly plays a role. A lot of very conservative Republicans got elected in 2010, and the Tea Party got a lot of attention, and some Tea Party Republicans have had a tendency to say inflammatory things. Like, say, Michele Bachmann.

Rival fact-checker Glenn Kessler of The Washington Post noted on Tuesday that with Bachmann's retirement, he'll lose some of his best material: "As one of our colleagues put it, 'The entire fact checking industry may have to hold a national day of mourning.'" In 2013 Bachmann has earned four Pinocchios, the most false rating the Post offers. Over her career, PolitiFact rated 15 Bachmann claims to be "pants on fire" ratings, its harshest rating. PolitiFact called her retirement "shocking." 

Bachmann was a fact-checker's dream because she was prominent, she got lots of attention, and she didn't mind throwing out easily disprovable statistics. But she's only a four-term member of Congress from Minnesota, and she doesn't have an important leadership role in the House. Nevertheless, she was elevated to national stardom by the cable news appearances that offered fact-checkers so much great material. And that helped her launch a presidential campaign.

Democratic Rep. Yvette Clarke was elected the same year as Bachmann, 2006. But PolitiFact didn't bother with Clarke when she went on The Colbert Report in September 2012 and said that Brooklyn still had slavery in 1898, five decades after New York abolished slavery, and three decades after the Civil War ended. "Slavery. Really? I didn’t realize there was slavery in Brooklyn in 1898," Colbert responded. "I'm pretty sure there was," Clarke said.

PolitiFact did not rate this claim. There are some obvious reasons why — Clarke is a little-known congresswoman; her claim was not about a current policy debate. Bachmann, on the other hand, was a presidential candidate.