Forty years ago, the United States government began a "war on drugs" whose cost so far is estimated at $1 trillion, and rising. In 2006, newly elected Mexican President Felipe Calderón began a crackdown on the drug-smuggling cartels—a "war on drugs" that really is a war, involving military troops and weapons and more than 10,000 dead so far. Americans buy drugs from the cartels and sell them guns, and Washington arguably provided the example for the Mexican government's hard-line tactics. So is America to blame for Mexico's drug war? That was the topic at last week's Intelligence Squared US debate at New York University.