A bipartisan group of Senators are coalescing around a bill against gun trafficking, but the reasoning they present for supporting the legislation has been undercut by an internal DOJ memo uncovered two weeks ago.

Sens. Patrick Leahy (D-VT), Dick Durbin (D-IL), and Kirsten Gillibrand (D-NY) are being joined by Sens. Susan Collins (R-ME) and Mark Kirk (R-IL) in pushing the Stop Illegal Trafficking in Firearms Act. 

The bill increases already existing penalties for knowingly purchasing a gun for someone who is legally barred from purchasing their own gun--and especially purchasing a gun that is passed to a criminal and/or gang member. 

According to Sen. Collins, the bill rests on the premise that "guns are frequently sold, resold and trafficked across state lines resulting in the proliferation of illegal firearms in our communities." 

The argument is that guns used in crimes are purchased in states with less strict gun laws and transported to states with stricter gun laws for criminal use. But a recently uncovered DOJ memo cites a 2001 study of gun violence in Los Angeles to show that this really isn't true.

The memo says: "contrary to conventional wisdom, that [guns] were being trafficked across state borders with less stringent regulations, such as Arizona and Nevada, we found that a majority of the guns used in crimes were purchased in Los Angeles County."