A new study finds that in June and July, a single website allowed sellers of more than 15,000 firearms in ten states to utilize the loophole in federal law allowing people to buy guns on the Internet without passing a criminal background check -- a loophole that conservative media claim doesn't exist.

Background checks -- designed to keep guns out of the hands of the dangerously mentally ill and convicted felons, who are banned by law from owning firearms -- are mandatory at retail stores under federal law. Between 1994 and 2009, nearly 1.8 million applications for firearms transfers were denied to prevent prohibited purchasers from buying guns. But private sellers who sell guns over the Internet or at gun shows are not required to perform such checks. In April, federal legislation aimed at requiring a background check on nearly every gun sale, termed the Manchin-Toomey amendment, failed to overcome a Senate filibuster, even though an overwhelming majority of Americans support such a law.

Prior investigations have found that this loophole for private sales is frequently exploited by gun traffickers and used to supply firearms to criminals, and that many Internet sellers are willing to complete sales even after being informed that would-be buyers couldn't pass a criminal background check. Nonetheless, conservative media have insisted that no such Internet or private sales loophole exists.

In a new study, the center-left think tank Third Way examined June and July listings in ten states whose senators did not support Manchin-Toomey (Alaska, Arizona, Arkansas, Georgia, Montana, Nevada, New Hampshire, North Dakota, Ohio, and Tennessee) on Armslist.com, a web portal devoted to gun sales. According to Third Way: