There's no question Google and other search engines (think Yahoo) make a lot of money advertising--even in a recession.

But Google can't just let anyone advertise -- its rulebook, for example, explicitly bans advertisers that use "deceptive, illegal, unethical, false or misleading practices." Moreover, Google's Online Pharmacy Qualification Process lays out specific rules on which online drugstore sites are allowed to advertise. It says, for instance, that sellers of online prescription drugs in the U.S. and Canada must register with the PharmacyChecker Verification Program.

But is PharmacyChecker a strong enough verification process?

It may not be.

Its list of banned "rouge" sites, for one,  pales in comparison to the over 22,000 sites that fail to meet the stricter standards of online verifier LegitScript.com.

Early this month, CNN exposed a PharmacyChecker-approved site that illegally sold controlled drugs from India without a prescription. Legitscript's  analysis of the site,  PharmNet.com,  found that CNN's order for the restricted antidepressant Xanax was made through PharmNet but was processed and paid through another site altogether. In fact, while PharmacyChekcer validated PharmNet, LegitScript rejected that site's application for approval.

It's worrisome if Google's verification process relies solely on PharmacyChecker, which approves sites that other verification processors do not.

Researchers at the National Center on Addiction and Substance Abuse (CASA) agree. In a July 2008 study, CASA found search engines' verification processes "far from perfect." Indeed after successfully finding prominent ads from rouge pharmacies in searches for controlled substances on Google and Yahoo, CASA wrote that their findings "suggest that these search engines are profiting from advertisements for illegal sales of controlled prescription drugs online."

Until search engines impose more stringent requirements  for online pharmacies, sites without the proper licenses and certifications will continue to generate sales. The online drug business is a fast-growing transnational enterprise, estimated by Mark Monitor to be worth $12 billion last year--there's a lot of potential ad dollars in there.