The Office of National Drug Control Policy says the $2 billion media campaign it launched last week will "realistically portray the harmful effects of drugs." After you've stopped laughing, you can have a look at the new ads (available at www.whitehousedrugpolicy.gov) and judge for yourself.

One of the ONDCP's TV spots is a cartoon showing a pot repeatedly hitting a man's head. "If you smoke pot one time," says the narrator, "it probably won't kill you. But if you keep smoking it, you might just get dumber and dumber and dumber and dumber and dumber."

At least the ad does not assert that pot is lethal. But since there has never been a documented case of death by marijuana, saying it probably won't kill you is not much of a concession.

In any case, the gesture toward honesty is overshadowed by the canard that marijuana makes you stupid. As usual in anti-drug propaganda, the ad conflates the short-term effects of intoxication with the unsubstantiated claim that smoking pot causes brain damage.

Another TV ad features Alex, a bleary-eyed teenager who looks like he was stoned during the interview. "Marijuana cost me a lot of things," he says. "I used to be a straight-A student. I was liked by all the neighbors....I was always a good kid." Then, "before I knew it, I was getting thrown out of my house....I just became a total loser."

Whether or not you accept Alex's self-serving explanation for his behavior, his story is far from typical. About 70 million Americans--one quarter of the population--have smoked marijuana, and few of them have suffered any significant harm as a result, let alone become "total losers." Some of them even went on to successful careers in politics.

That uncomfortable fact helps explain why government officials continue to insist that marijuana is either more dangerous than it used to be or more dangerous than we used to think. Since there is scant evidence to back up such claims, they are best understood as ritual incantations intended to ward off charges of hypocrisy.

In explaining the need for the new ads, which are being produced in cooperation with the Partnership for a Drug-Free America, the ONDCP laments that the percentage of teenagers who think smoking marijuana is a "high-risk behavior" has dropped in recent years. The campaign is supposed to help reverse that trend.

The thing is, smoking marijuana isn't a high-risk behavior. So the media campaign will be considered successful to the extent that it encourages kids to believe a lie.

The campaign's supporters could reply that it's aimed at reducing drug use, not disseminating facts. But even by that measure, there is little reason to believe it will work.

As an article in the April 27 issue of Brandweek showed, the empirical basis for the ad campaign is meager. "There's no solid data that show the media campaigns create meaningful changes in behavior," said one expert. Others agreed, noting the uncertainty of relying on teenagers to be candid in surveys and the difficulty of isolating the effect of particular messages.

The ONDCP says it will measure the media campaign's impact. But since the ads are being used throughout the country, that will be hard to do. More likely, the campaign's sponsors will simply wait for teenage drug use to decline and then take credit for it. They have plenty of wiggle room, since they emphasize that it can take several years for ads to affect behavior.

If they took that claim seriously, they might wonder why teenage drug use started to rise several years after the first wave of ads from the Partnership for a Drug-Free America, which included the much-ridiculed spot comparing a drug user's brain to a fried egg. Could the scare tactics be backfiring?

The Clinton administration does not seem to have considered that possibility. "The [new] ads are designed to be jarring and provocative," says a White House spokesman. "They get your attention."

But getting your attention and delivering a credible message are two different things. One of the new ads features a young woman who uses a frying pan to smash an egg and wreck a kitchen. To her, this symbolizes what happens to your brain and your life "after snorting heroin." To me, it symbolizes what happens to the truth when advertising agencies collaborate with drug warriors.