Study Claims Lifting the U.S. Assault Weapons Ban Led to Hundreds of Homicides in Mexico

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Sept. 5 2013 11:18 AM

Study Claims Lifting the U.S. Assault Weapons Ban Led to Hundreds of Homicides in Mexico

A US-made M4 assault rifle with a mounted M-203 grenade launcher who belonged to Edgar Valdez Villareal, aka 'La Barbie', of the Beltran Leyva drug cartel, is shown to the press at the Federal Police headquarters in Mexico City, on August 31, 2010.

Photo by ALFREDO ESTRELLA/AFP/Getty Images

A too-often ignored factor in the U.S. gun control debate is the role American guns play in Mexico’s brutal drug violence. Because gun control laws are far stricter in Mexico, U.S. gun stores have become popular destinations for cartels looking to stock up.  (Mexico has only one gun store, which sells only small-caliber weapons to licensed buyers.) One study found that 253,000 U.S. guns are smuggled into Mexico annually, representing about 2.2 percent of all U.S. gun sales. 

Joshua Keating Joshua Keating

Joshua Keating is a staff writer at Slate focusing on international affairs and writes the World blog. 

Measuring the effect these guns have on crime levels in Mexico has been challenging, given the difficulty of tracking guns from the U.S. into Mexico. (The ATF’s now-infamous “Fast and Furious” program was a horrifically botched effort to do just that.)


A recent study published in the American Political Science Review attempts to measure the impact of U.S. gun laws on Mexican violence by exploiting an interesting natural political experiment. When the 10-year U.S. assault weapon ban expired in 2004, the selling of assault rifles became legal in the border states of Texas, Arizona, and New Mexico, but not California, which had a pre-existing state-level ban. Authors Arindrajit Dube of the University of Massachusetts and Oeindrila Dube and Omar Garcia-Ponce of NYU looked at whether violence increased more in areas of Mexico near border states that were selling these weapons.

They found that in Mexican municipios—the equivalent of U.S. countiesneighboring entry ports in the three states without the ban saw “total homicides rise by 60% as compared to municipios 100 miles away. This implies an additional 238 homicides in the area within 100 miles of the border, in each of the two years after the 2004 policy change. To put the size of the effect into perspective, the additional homicides stemming from the FAWB expiration represent 21% of all homicides in these municipios during 2005 and 2006. Similarly, the additional gun related homicides represent 30% of all such deaths over this period.”

The result held when they controlled for the total level of cartel activity and economic conditions in these regions. The experiment cuts off at 2006, when drug violence all over Mexico exploded following the beginning of President Felipe Calderon’s all-out campaign against the cartels.

Of course, this is just a part of the picture of violence in Mexico. The vast majority of the country’s homicides are carried out with handguns (also purchased in the U.S.), not high-caliber assault weapons, so the effect of these bans is probably actually minimal in the larger scheme of things. The study addresses this by noting that the number of assault weapons seized also greatly increased in the areas studied.

 But even if the weapons in question aren’t the primary cause of Mexico’s bloodshed, the study gives an indication of why America’s gun debate is far from just a domestic issue.  



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