ANGERED BY erratic Latin performance in the war against drugs, the American Congress on its own legislated tough economic penalties. The initiative may have bought some extra local effort in some Latin places. More likely, by provoking the nationalism of targeted Latin governments, it has weakened enforcement. That "certification" exempts the United States has had a particularly noxious effect, since Latins rightly regard the burning American demand for their illegal products as the engine driving the whole drug train.

Which is how Latins, with American help, have now invented a bureaucratic device known as the Multilateral Evaluation Mechanism. Procedurally, it's a call for annual factual reports on how each of 34 Organization of American States members is stemming production, trafficking, consumption and crime. Politically, it's an attempt to cut the ground out from under American certification law by itemizing drug-war shortfalls without tempting punishment by the United States. The new tool "creates a new and level playing field in the evaluation process," says OAS Secretary General Cesar Gaviria. "All countries will evaluate all countries."

Most Americans, we would guess, are less interested in evaluation than in action. Fair evaluation can smooth out some political bumps. But effective action can slow the flow of drugs. A good number of congressmen, moreover, are bound to ask whether anything with the four-letter word multilateral in it is anything more than a way for resentful Latin governments to fend off American pressure. Still, the Multilateral Evaluation Mechanism, which is being wheeled out for a meeting of hemispheric anti-drug chiefs in Washington this week, could make a difference. Anything that can contribute to taming the drug scourge, especially by cutting American demand, deserves a try.