Who is supplying guns to Mexican drug traffickers?

The answer has become one of the most polemical in the gun rights debate, with Mexico blaming lax US gun laws and gun rights advocates saying that blame is misplaced.

Statistics are cited. Methodologies are dismissed.

A new report released this week by US senators has renewed the fight, with valid points coming from both sides of the divide.

The report, issued by Sen. Dianne Feinstein (D) of California, Sen. Charles Schumer (D) of New York, and Sheldon Whitehouse (D) of Rhode Island, bases its conclusions on US Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) statistics. The report states that of 29,284 arms handed over for tracing by Mexican authorities in 2009-10, some 70 percent came from the US.

The senators conclude that military-style guns have “contributed to Mexico’s dangerous levels of violence,” and that legislation to tighten gun laws, like reinstating the expired Assault Weapons Ban, is in order.

Cherry-picked data?

The ATF's statistic has been controversial since it was first cited two years ago. (At that time the number was even higher, at around 90 percent. It may have dropped now because more guns are getting traced today).

Nonetheless, it only accounts for guns seized in Mexico, and of those, the ones that the Mexican government submits for tracing. Many see that as an incomplete set of data, leading them to dismiss the statistic as inaccurate.

“It is completely misleading. There is a huge population of guns that Mexicans confiscated that they don’t submit to trace to the ATF,” says Robert Farago, the managing editor of the website The Truth about Guns.

Still, it is estimated that about 30 percent of weapons seized in Mexico are submitted for tracing. And whether it is 90 percent or 70 percent that come from the US within that pool, that is still a large number of American guns circulating in Mexico.

“What is clear beyond a doubt is that there are an enormous amount of guns coming from US," says Tom Diaz, senior policy analyst at the Violence Policy Center in Washington.

Mr. Diaz argues in the report The Militarization of the US Civilian Firearms Market that those guns are increasingly modeled after the military. He says that semiautomatic assault rifles, 50 caliber anti-armor sniper rifles, and armor-piercing handguns are the “weapons of choice” for drug organizations in Mexico.

Mr. Farago does not doubt that military-style weapons are in the hands of drug traffickers in Mexico. But he says that is because weapons from the Mexican military are seeping into drug traffickers’ hands.

Traffickers also acquire military weapons from other countries.

“Grenades and fully automatic machine guns are not sold at Bob’s gun store in Arizona,” Farago says. “This is a distraction technique. There is not an iron river of guns from [US] gun stores.” [Editor's note: The original version of this story misnamed the source of this quote.]

The newest report comes as the ATF is under fire for a sting operation that purposefully allows some automatic weapons to be smuggled south of the border so it can track them. Mexican authorities have long faulted robust American demand for drugs and lax gun laws for their woes.

Calderón: 'I accuse the US weapons industry'

Mexican President Felipe Calderón reiterated that stance bluntly this week. "I accuse the US weapons industry of [responsibility for] the deaths of thousands of people that are occurring in Mexico," Mr. Calderón said over the weekend, while on a visit to California. "It is for profit, for the profits that it makes for the weapons industry."

Diaz says the Mexican government needs to get even tougher on the US arms industry, even finding a channel to sue it. But gun rights activists have long said this is misplaced blame – that gun laws in the US are much laxer than in Mexico and yet the same levels of violence and impunity are nowhere near what Mexico is encountering: to date more than 35,000 drug-related deaths in the past four and a half years.

In fact, Farago says Mexico should loosen its restrictions on rights to bear arms, even allowing the US to supply citizens with weapons. “We should be supplying guns to Mexican citizens who cannot defend themselves,” he says. “They are completely at the mercy of these drug [traffickers].”