Representative Ernest Istook (R‑Okla.) has discovered a mortal threat to the republic. The threat is a display ad placed by a pro-drug legalization group, Change the Climate, Inc., on Washington D.C.‘s bus and subway system. The ad showed a young couple, with the caption: “Enjoy Better Sex! Legalize and Tax Marijuana.”

And to deal with this outrage, Istook has introduced a measure to financially penalize Washington’s Metro transit authority for running the ad. Moreover, Istook’s bill would prohibit any transit system that receives federal funds from running advertising from a group that advocates decriminalizing or legalizing marijuana.

This is hardly the first time that the blackjack of withholding federal funds has been used to coerce recipients into embracing pet policies of politicians, but it has to be one of the more odious. Istook’s bill shows utter contempt for the First Amendment, and indeed for the entire concept of political debate.

But drug warriors have repeatedly showed their intolerance of opposing views — and their eagerness to use the power of government to suppress critics. For example, in the mid-1990s, the late Rep. Gerald Solomon (R‑NY) attempted to have the tax-exempt status of the Cato Institute revoked because it had the temerity to sponsor discussions of the legalization option.

The most ominous proposal for repressing pro-drug reform speech comes (not surprisingly) from the United Nations. The UN’s International Narcotics Control Board has issued a report implicitly calling on member states to criminalize opposition to the war on drugs. Citing the 1988 UN Convention Against Illicit Trafficking in Narcotic Drugs and Psychotropic Substances, the INCB asserts that all governments are obligated to enact laws that prohibit “inciting” or “inducing” people to use illegal drugs and to punish such violations as criminal offenses.

If such a vague and chilling restriction on freedom of expression were not odious enough, the UN board contends that any portrayal that shows illicit drug use “in a favourable light” constitutes incitement and therefore should be banned as well. Since the report also repeatedly denounces medical marijuana initiatives as well as decriminalization or legalization proposals, even the most sedate advocacy of changing prohibitionist drug laws might run afoul of the censorship regime being pushed by the United Nations.

It is not reassuring that the U.S. government has pledged to cooperate with the UN group’s global anti-drug efforts. Although Washington has not explicitly endorsed the censorship recommendations, neither has it stated that the United States rejects such proposals — even though it certainly could have added that caveat. Indeed, one official pledged “absolute cooperation” with the UN’s drug control programs.

Those who might be tempted to dismiss the significance of efforts to gag proponents of drug legalization should know that government officials have already sought to implement censorship measures (albeit more limited ones than the comprehensive bans suggested by some drug warriors). For example, authorities in Maryland prosecuted an individual for publicly divulging the identity of two undercover narcotics officers. Attempting to prohibit such disclosures by charging the defendant with “obstructing and hindering a police officer,” Maryland officials endeavored to give undercover narcotics officers the same protection that Congress afforded to the CIA and other intelligence agents to wage the Cold War and the subsequent war on terror.

Although the Maryland Court of special appeals eventually overturned the conviction on the grounds that it violated the defendant’s state and federal constitutional rights to freedom of speech, several aspects of the case remain troubling. First, the fact that Maryland authorities sought to impose such censorship in the first place; second, that the defendant was convicted in a trial court; and third, that the Court of Appeals overturning the conviction on a divided vote. It is hardly reassuring that a minority of the justices were willing to allow such a violation of the First Amendment’s guarantee of freedom of speech to pass muster.

Such examples suggest that some advocates of drug prohibition regard the “war” on drugs as more than a metaphor. Pervasive intolerance is also all too typical of a wartime mindset in which opponents are seen, not merely as people who hold a different point of view, but as traitors to a noble cause.

Regardless of one’s position on drug legalization, Americans who believe in freedom of expression and in the importance of political debate ought to condemn Istook’s measure and all other attempts to stifle the pro-legalization case. Otherwise, the First Amendment might become the most prominent example of “collateral damage” in the war on drugs.