Advertising dissent: drug warriors back down.

IN THE FALL of 2003, Rep. Ernest Istook (R-Okla.) was outraged by ads in Washington, D.C.'s Metro system urging the government to "Legalize and Tax Marijuana." So he did what any intolerant, power-mad politician would do: He wrote legislation to ban such speech, not only from Metro buses, trains, and stations but from every mass transit system in the country that receives federal funds. The ban became law as part of a 2004 appropriations bill.

After unsuccessfully submitting an ad critical of marijuana prohibition to the Metro system in February 2004, the American Civil Liberties Union and three drug policy reform groups challenged Istook's amendment in federal court. Last June, U.S. District Judge Paul Friedman ruled that the law, which forbade anti-prohibitionist ads while permitting pro drug war messages, was a clear example of "viewpoint discrimination" and therefore presumptively invalid under the First Amendment.

Although the Justice Department initially said it would appeal Friedman's decision, Acting Solicitor General Paul Clement concluded the government did not have a leg to stand on. In a December 23 letter to Congress, Clement said "the government does not have a viable argument to advance in the statute's defense and will not appeal the district court's decision."

Former solicitors general Charles Fried and Seth Waxman told The Wall Street Journal this sort of decision is highly unusual. That means either that Congress rarely passes laws that are blatantly unconstitutional--or that the government's lawyers can almost always find a "viable argument" to save them.