The New York Times describes a major obstacle facing the U.S. in responding to a demand from Mexico to curb the flow of arms to drug cartels: The federal system for tracking gun sales, crafted to avoid infringements on Second Amendment rights, makes it difficult to spot suspicious trends quickly and to identify people buying for smugglers. In some states along the Southwest border where firearms are lightly regulated, gun smugglers can evade detection for months or years.
In Texas, New Mexico, and Arizona, dealers can sell an unlimited number of rifles to anyone with a driver's license and a clean criminal record without reporting sales to the government. There is even less regulation at gun shows in these states. Private sellers, unlike licensed dealers, are not obligated to record the buyer's name, much less report the sale to the federal government. Mexican officials have repeatedly asked the U.S. to clamp down on the flow of weapons and are likely to bring it up again with President Obama when he visits tomorrow.