will.i.am sues Pharrell

will.i.am's feud with Pharrell Williams has become a full-on legal spat - the Black Eyed Peas star has filed a lawsuit against his fellow hitmaker/producer.

Will previously fired off a cease and desist letter, demanding that Pharrell drop the 'I AM' from his I AM OTHER YouTube.com site, prompting Pharrell to ask a judge to protect his right to use the moniker.

And now will.i.am is countersuing his fellow hitmaker/producer, claiming he has a long, copycat history, noting Pharrell is being sued by Marvin Gaye's family for allegedly ripping off Got to Give it Up for his summer anthem Blurred Lines, according to TMZ.com.

Will claims out Williams' I AM OTHER will confuse people because both stars are on the same record label and they have similar musical styles.