Craigslist took down Adult Services in the U.S. four days ago, replacing it with the word "censored" without explanation. Advocates seized on the ambiguous move today, calling on Craigslist to remove the infamous section in cities across the world.

It's hard to say what the effect of shuttering Adult Services will be on the profitability of the sex trade. But it will certainly curtail Craigslist's ability to profit from sex traders.

The New York Times estimates Adult Services ads could have brought in $44 million for Craigslist this year, based on the $10 it costs to post and $5 to repost. Post-censorship, ads for sex are migrating to other classifieds sites and other sections of Craigslist. The first stop after getting kicked out of Adult Services is the personals section "Casual Encounters," where it is free to post an ad.

By focusing on Adult Services, Craigslist's opponents are targeting a symptom instead of a problem.

"If Craigslist is seriously committed to ending the site's use as a platform for sex trafficking and the sexual enslavement of children and young women, it will immediately close the remaining sections around the world," the groups said in statement.

Ending the site's use as a platform. Not ending abusive sex trafficking, because shutting down Adult Services won't do that. Really, advocates want Craigslist to stop being a "digital pimp," to borrow Microsoft researcher Danah Boyd's phrase. From an advocate's perspective, the fact that Craigslist makes money off of prostitution and sex trafficking - some of it voluntary, some of it coerced and some involving minors - colors anything the company says.

Profit is a powerful motivator and the fact that Craigslist makes so much money off these ads undermines its moral authority [UPDATE: A reader points out that Craigslist started charging for these ads after negotiations with attorneys general and National Center for Missing and Exploited Children, so that credit card information could be kept on file. But the ads now constitute a significant portion of the site's revenue]. But is ending that revenue stream a worthy pursuit, given the strong arguments that Craigslist does more good than harm by making it easy for law enforcement to find and track sex traffickers, and empowering prostitutes to escape often-abusive middlemen?

On Monday, there were 23,453 ads posted in the "Adult Services" section across Craigslist sites for cities outside the U.S., according to the anti-human trafficking advocacy group The Polaris Project. By comparison, there were 12,834 ads posted in Adult Services" in the U.S. on Tuesday, July 21, 2009. (Singapore, where the Internet is censored for porn, is the only Craigslist site without an Adult Services section. Ironically, Singapore has an aboveground sex industry regulated by the government.) Getting the section taken down in the rest of the world is now top priority for the groups behind this push.

Craigslist fumbled its public response to accusations that it encourages abusive prostitution (see Feeling Burned By the Press, Craigslist Hunkers Down), even though it has two strong arguments from both the free speech and human rights angles as well as the protection of the law. Perhaps we'll see a better defense based on data collected during the Adult Services blackout when Craigslist testifies before Congress during a hearing on sex trafficking of minors on Sept. 15.