Reports that the handgun used by Boston Marathon bombing suspect Tamerlan Tsarnaev originated in Maine should come as no surprise given guns are routinely trafficked from states with weak gun laws to states with stronger gun laws like Massachusetts. Meanwhile, attempts to create a federal law to crack down on gun trafficking have been stifled by the National Rifle Association.

Following the April 15, 2013, bombings that left three dead and hundreds wounded, the Tsarnaev brothers attempted to elude a massive police manhunt. On the evening of April 18 a Ruger handgun was used by the brothers to kill MIT police officer Sean Collier. Hours later the pistol was used again in a firefight that left MBTA officer Richard Donohue seriously wounded. On May 12, Los Angeles Times federal law enforcement and terrorism reporter Richard Serrano reported that the firearm was purchased at a Maine gun store, and “passed” to a well-known Portland, ME gang leader, before being obtained by Tsarnaev.

Massachusetts has the sixth strongest gun laws in the United States and also has the second lowest gun death rate, according to rankings by The Brady Campaign to Prevent Gun Violence and the Law Center to Prevent Gun Violence. When guns are used in crimes in Massachusetts, they are most often trafficked from other states (although the National Rifle Association's official state affiliate has denied this regularly occurs).

The Bureau of Alcohol, Tobacco, Firearms and Explosives was able to determine the origin of 999 Massachusetts crime guns in 2012; 453 came from in-state while 546 were trafficked from other states. Maine accounted for the second largest number of out of state gun traces after New Hampshire. The top six crime gun importers to Massachusetts -- New Hampshire, Maine, Florida, Georgia, North Carolina, and South Carolina -- all received a D or worse grade in the Brady Campaign/LCPGV gun law ranking. Overall the rankings found a correlation between weak gun laws and the exporting of crime guns into states with strong gun laws.

There is no “direct” federal law that makes gun trafficking a crime. Currently gun traffickers can be charged with lying on the background check form about who the gun's intended owner is, but federal prosecutors are hesitant to devote resources to what would amount to paperwork violations that are difficult to prove under current law.

A significant attempt was made in the U.S. Senate to create a strong federal gun trafficking law following the mass shooting at Sandy Hook Elementary School, but the plans ultimately were stifled by the NRA and its congressional allies.

Sen. Patrick Leahy (D-VT) took the first step towards a meaningful federal gun trafficking bill by sponsoring the Stop Illegal Trafficking in Firearms Act of 2013. That bill advanced out of committee and to the Senate floor. Leahy then joined forces with Sens. Kirsten Gillibrand (D-NY), Mark Kirk (R-IL), and Susan Collins (R-ME) and gave concessions to the NRA that weakened the bill in order to craft bipartisan legislation. The result was not as strong as the original proposal, but it would have still created severe penalties for gun trafficking.

The plan was for this proposal to be offered as an amendment while the U.S. Senate voted on legislation to expand background checks to all commercial sales. But before Leahy's amendment could be voted on, the Senate voted on substitute legislation approved by the NRA that included the NRA's version of gun trafficking legislation.

According to centrist think tank Third Way, the NRA language “would just be one more toothless federal gun law cleverly written to accomplish practically nothing,” because it would “dismantle the straw purchaser provisions at the heart of” Leahy's original bill and because the NRA bill's “standard of proof is so high that it would be impossible to prosecute.” Third Way added, “The NRA gambit is simply an attempt to distract the Senate from supporting the much stronger measure approved by Judiciary. The Chairman's [Sen. Leahy] bill would staunch the flow of guns into the illegal market and keep them out of the hands of criminals.”

With a handful of exceptions, Republicans voted for the new NRA-backed substitute and then against Leahy's gun trafficking amendment. Although neither amendment was adopted due to a procedural move that created a 60 vote threshold for adoption, the NRA demonstrated its intense willingness to weaken and interfere with federal legislation to crack down on gun trafficking.