The Republican budget bill passed in the House Saturday morning blocks a request from federal officials for broader authority to fight gun trafficking to Mexico.
The provision would bar the government from requiring gun dealers in southern border states to report bulk purchases of assault weapons – an emergency measure designed to stem the flow of guns to Mexico's violent drug cartels.
Rep. Dan Boren (D-Okla.), who sponsored the provision, said it will "protect the Second Amendment rights of law-abiding citizens."
"I remind my colleagues this amendment carries the full support of the National Rifle Association," Boren said on the floor Friday night.
His amendment passed 277 to 149. Forty-one Democrats voted in favor of the bill, and two Republicans – Reps. Peter King (N.Y.) and Brian Bilbray (Calif.) – opposed it. King, the chairman of the Homeland Security Committee, has often been at odds with GOP leaders over gun reform.
In December, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) asked for new powers to require gun dealers in Mexican border states to report sales of two or more assault weapons to the same buyer within five work days.
The ATF's emergency request was a response to spiraling drug violence in Mexico, where more than 30,000 people have been killed since 2006, when President Felipe Calderon launched a crackdown against the country's powerful cartels. Thousands of the guns used by those cartels have been traced to gun dealers in the United States.
A 2009 report from the Government Accountability Office found that more than 20,000 – or 87 percent – of the guns confiscated from the Mexican cartels between 2004 and 2008 originated in the U.S. More recently, the figure has risen to over 90 percent.
The Obama administration is still weighing whether to grant the ATF request, but the Boren amendment would make the White House decision irrelevant.
Boren, who formed the Second Amendment Task Force in the last Congress, said his opposition to the ATF's request is three-fold. First, it puts an additional paperwork burden on gun dealers. Second, it creates a federal catalog of assault weapons buyers, thereby violating their privacy. And finally, he says ATF doesn't have the legal authority to require such reporting.
The ATF proposal applies only to dealers in Arizona, California, New Mexico and Texas. Affected guns must be semi-automatic, must carry ammunition larger than .22 caliber, and must feature a detachable ammunition clip — characteristics favored by the Mexican drug cartels.
Boren said those guns represent some of the "most popular rifles used by millions of Americans for self-defense, hunting and other lawful purposes."
Gun control advocates both on and off Capitol Hill have backed the ATF's emergency request, arguing that the sheer number of U.S. guns abetting Mexican drug crime makes it a necessary step.
"Last year, the U.S. military announced that if the drug war continues it will cause the Mexican government to collapse and the cartel war would spread over the border into the U.S.," Rep. Judy Chu (D-Calif.) said on the floor Friday. "This amendment makes the drug war worse."
Chu is spearheading a letter urging the White House to approve the ATF's request.