Yahoo! has filed a complaint in the Northern District of California against Facebook, possibly ushering in a new era of patent wars among internet companies. There are 10 patents being asserted, covering advertising, privacy, customisation, social networking and messaging technology. "For much of the technology upon which Facebook is based, Yahoo! got there first and was therefore granted patents by the United States Patent Office to protect those innovations," said Yahoo! in the complaint. The lawsuit followed reports that Yahoo! in February demanded licensing fees from Facebook, which Facebook apparently refused. Charles Verhoeven of Quinn Emanuel is representing Yahoo!, while Cooley's Stephen Neal and WilmerHale's William Lee will be representing Facebook. In a statement, a Facebook spokesperson called the complaint "puzzling" and said: "We're disappointed that Yahoo, a longtime business partner of Facebook and a company that has substantially benefited from its association with Facebook, has decided to resort to litigation."