Reply #4: That "90 percent" figure has been debunked innumerable times on these forums

[slackmaster]

It is based on a small percentage of "recovered" weapons for which a trace was actually attempted.

...There's no dispute that thousands of handguns, military-style rifles and other firearms are purchased in the U.S. and end up in the hands of Mexican criminals each year. It's relatively easy to buy such guns legally in Texas and other border states and to smuggle them across.

But is it true as President Obama said, that "more than 90 percent of the guns recovered in Mexico come from the United States?" No, it's not.

The figure represents only the percentage of crime guns that have been submitted by Mexican officials and traced by U.S. officials. We can find no hard data on the total number of guns actually "recovered in Mexico," but U.S. and Mexican officials both say that Mexico recovers more guns that it submits for tracing. Therefore, the percentage of guns "recovered" and traced to U.S. sources necessarily is less than 90 percent.

Furthermore, the 90 percent figure is based on a badly biased sample of all Mexican crime guns. Law enforcement officials say Mexico asks the U.S. to trace only those guns with serial numbers or other markings that indicate they are likely to have come though the U.S....

Source: http://latimesblogs.latimes.com/washington/2009/04/barack-obama-gun.html

The real source of Mexican crime weapons would probably be a serious embarrassment to Mexican law enforcement and military people. Calderon and others are misusing information in an ongoing attempt to get the US to ratify a treaty that would be at odds with our constitution. They're trying to deflect blame for Mexico's crime problems away from their own inability to control it.