by David Boaz

About the author: David Boaz is the executive vice president of the Cato Institute, a libertarian think tank in Washington, D.C.

Ours is a federal republic. The federal government has only the powers granted to it in the Constitution. And the United States has a tradition of individual liberty, vigorous civil society, and limited government: just because a problem is identified does not mean that the government ought to undertake to solve it, and just because a problem occurs in more than one state does not mean that it is a proper subject for federal policy.

Perhaps no area more clearly demonstrates the bad consequences of not following such rules than drug prohibition. The long federal experiment in prohibition of marijuana, cocaine, heroin, and other drugs has given us unprecedented crime...