Yahoo and three other companies have been sued for trademark infringement, accused of bidding on a trademarked brand as keywords on Google, writes MediaPost. The lawsuit was filed in federal district court in Colorado by JP Enterprises, which runs online dating service lovecity.com. The suit alleges that Yahoo and the others of bidding on "lovecity," "lovecity.com" and "www.lovecity."

Yahoo and two of the other named companies in the complaint run their own online personals services; HDVE operates True.com, and Spark Networks runs several, including AmericanSingles.com and JDate.com.

The JP Enterprises complaint says those companies' keyword-purchasing practices cause consumer confusion, hurt the "lovecity" brand and drive down sales. It accuses Yahoo and the other companies of "tarnishing the goodwill and reputation" of lovecity and "causing lost sales."