Buying keywords on search engines for advertising campaigns has proven to be one of the most successful business opportunities for the search engines, and most now are offering a service along these lines, including Yahoo and Google. But a recent courtcase, settled after 5 years between Netscape and Playboy, raises some interesting issues for the search engines.

Playbox took Netscape to court saying Netscape had allowed search keywords to be purchased including “playboy” and “playmate.”, which of course Playboy lays claim to. The case was earlier dismissed, but Playboy kept trying.

“Complaints over misuse of trademarks in search engine ads are growing because of the influence of such programs from Google and Yahoo-owned Overture Services. Google, for example, faces trademark complaints from advertisers of its popular keyword-auction program. In December, Google asked a court to rule on whether its keyword-advertising policy is legal as a result.”

Of course the big question is, how do the search engines police this? Anyone can sign up for Google’s keyword advertising, and enter any words they like for their campaign. Does Google now have to out in place a system which checks those words against lists of trademarked, patented or otherwise protected words? That could turn into something of a problem.