The drug-fueled murders and mayhem in Mexico bring to mind the Prohibition-era killings in Chicago. Although the Mexican violence dwarfs the bloodshed of the old bootleggers, both share a common motivation: profits. These are turf wars, fought between rival gangs trying to increase their share of the market for illegal drugs. Seventy-five years ago, we sensibly quelled the bootleggers' violence by repealing the prohibition of alcohol. The only long-term solution to the cartel-related murders in Mexico is to legalize the other illegal drugs we overlooked when we repealed Prohibition in 1933.

In 2000, the Mexican government disturbed a hornets' nest when it began arresting and prosecuting major distributors of marijuana, cocaine, heroin and amphetamines. Previously, the cartels had relied largely on bribery and corruption to maintain their peaceful co-existence with the Mexican government. Once this pax Mexicana ended, however, they began to fight not only the government but among themselves. The ensuing violence has claimed the lives of at least 10,000 in Mexico since 2005, and the carnage has even spilled north to the United States and south to Central and South America.

Some say that this killing spree -- about 400 murders a month currently -- threatens the survival of the Mexican government. Whether or not that is the exaggeration that Mexican President Felipe Calderón insists it is, Mexico is in crisis. The Mexicans have asked the Obama administration for help, and the president has obliged, offering material support and praising the integrity and courage of the Mexican government in taking on the cartels.

The U.S. should enforce its laws against murder and other atrocious crimes and we should cooperate with Mexican authorities in helping them arrest and prosecute drug traffickers hiding out here. But what more can and should we do?

Is gun control the answer? President Calderón asserts that the cartels get most of their guns from the U.S. We could virtually disarm the cartels, he implies, if we made it harder to buy guns here and smuggle them into Mexico. President Obama has bought into this claim and has made noises about reducing the availability of guns. However, even if the Obama administration were able to circumvent the political and constitutional impediments to restricting Americans' access to handguns, the effect on Mexican drug violence would be negligible. The cartels are heavily armed now, and handguns wear out very slowly.