by Maggie Gallagher

Demi Moore and Ashton Kutcher's foundation, the Demi and Ashton (or DNA) Foundation, is dedicated to combatting sex slavery around the world.

This week the two superstars announced a new social media campaign: "Real Men Don't Buy Girls."

Visit the website's "News" section, where a series of somewhat comical ads feature studly celebrities who illustrate truths about what "real men" do and don't do, with voice-overs from the same guy who appears in the famous Old Spice commercials

There's a theory behind the ad campaign, known as "demand reduction."

Steve Wagner, the director of the Human Trafficking Program at the U.S. Department of Health and Human Services from 2003 to 2006, runs an organization called Renewal Forum, which is setting up a model cities project to combat the commercial sexual exploitation of underage girls in Kansas City.

"Sex trafficking is an economic crime; it's motivated by greed," he tells me. "Traffickers often prefer underage girls, runaways and throwaways, because they are easier to manipulate and control. The demand side is what is driving this crime. To end sex trafficking of minor girls will require not only helping the victims but reducing the demand."

The best-researched strategy for reducing demand is something called "johns school." In San Francisco, men arrested for soliciting prostitution for the first time have the option of paying a fine and going to a one-day class on the negative effects of prostitution -- on the prostitutes, the community and even on the johns themselves.

A March 2008 Justice Department evaluation of the effectiveness of San Francisco's First Offender Prostitution Program found that the program "has been effective in substantially reducing recidivism among men arrested for soliciting prostitutes," and "is cost-effective, operating for over 12 years at no cost to taxpayers and generating nearly $1 million for recovery programs for providers of commercial sex."

The johns-school curriculum focused on the negative consequences for johns, including legal issues, vulnerability to assault and robbery, as well as the health risks of sex with prostitutes. But the johns school also gave men new information on the negative effects of prostitution on the prostitutes, including rape and assault, drug addictions, and the reality for many of coercive sex trafficking. The curriculum also includes information on the negative effect of prostitution on the community and concludes with information on sexual addiction -- and where help can be sought.

Research into men who patronize underage prostitutes suggests that more often than not, these men are not seeking minors specifically.

In the fall of 2009, the Schapiro Group (a Georgia market research company) conducted a study of men who seek prostitutes in the Atlanta area. Researchers placed ads on Craigslist, and then subtly "interviewed" the men who called, expanding their knowledge of men who pay for minor girls to have sex.

The good news is that very few of these men are specifically seeking juveniles. The bad news is that when offered three specific and escalating warnings that the prostitute might be underage, more than four in 10 johns did not care.

The worst mistake is to imagine that johns having sex with underage sex trafficking victims are men with abormal psychology. These are mostly not pedophiles or predators as we understand those terms. As the Schapiro Group put it, the commercial sexual exploitation of children "can only exist as a commercial enterprise if it is a sadly normal practice in our society. ... Men who purchase sex tend to come from normal backgrounds and seem no more likely to suffer from apparent pathologies than the rest of the adult male population."

It seems a fairly minimal standard of sexual conduct, but every society, including ours, clawing its way back to sanity from a sexual revolution, has to start somewhere.

Real men don't buy girls.

(Maggie Gallagher is the founder of the National Organization for Marriage and has been a syndicated columnist for 15 years.)