WILL.i.am, one of the judges on BBC talent show The Voice, is suing fellow US pop music star Pharrell Williams over his use of the phrase "I am" .
Mr Williams set up his own "i am OTHER" brand to promote talent online and said he was searching for a "diverse group of optimistic, bright minds".
But Will.i.am, real name William James Adams, took exception and filed a lawsuit claiming that he owns the copyright to the phrase "I AM" and that Pharrell's logo is "confusingly similar" to his "i.am+" iPhone camera add-on, according to court documents.
The "registration of the mark.. is likely to dilute the I AM mark and the will.i.am mark", the documents claim.
Pharrell Williams told Rolling Stone magazine: "I am disappointed that Will, a fellow artist, would file a case against me.
"I am someone who likes to talk things out and, in fact, I attempted to do just that on many occasions.
"I am surprised in how this is being handled and I am confident that Will's trademark claims will ultimately be found to be as meritless and ridiculous as I do."
Will.i.am, founder of the hip hop band The Black Eyed Peas, has recently faced accusations of copyright infringement himself after producers Arty and Mat Zo accused him of sampling their song "Rebound" without their permission on his latest recording with singer Chris Brown.
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