Pharrell Williams has filed a lawsuit against will.i.am of the Black Eyed Peas over the phrase "i am."
In the suit, Williams asks a judge to rule that his trademark for his "i am OTHER" company does not infringe on will.i.am's "I AM" trademark for his line of businesses.
The suit, filed Monday in New York federal court and obtained by ABCNews.com, refers to will.i.am by his real name, William Adams.
"The complaint seeks a declaration from the Federal Court in New York that i am Other does not infringe, dilute or unfairly compete with will.i.am or any of Mr. Adams' alleged 'I AM' trademarks, virtually all of which have been rejected by the USPTO [United States Patent and Trademark Office]," Williams' attorney, Brad Rose, said in a statement to ABCNews.com.
Williams is seeking a declaratory judgment of non-infringement.
An attorney for will.i.am did not respond to ABCNews.com's request for comment.
The two music megastars have been battling over the use of the phrase since last December, when will.i.am sent Williams a cease and desist letter demanding that he stop using the "I AM" trademark for his company, i am OTHER, which he launched in 2010.
Williams' company produces the hit Web series "Awkward Black Girl," as well as other programming, apparel and music artists.
Will.i.am uses "I AM" for his line of endeavors, including IAMAUTO, in which he joined with Chrysler to design a car, and his charity foundation, i.am.angel.
In the lawsuit filed Monday, Williams claimed that will.i.am has been using the words in a Dr. Seuss-inspired way, as in, "Sam I am; I am Sam; I am Sam; Sam I am."
"In contrast, the 'I AM OTHER' mark means 'I am something else,' leaving what that 'else' is to the imagination of the consumer. It certainly does not mean 'I am Will,'" Williams argued in the suit.
Last month, will.i.am filed a notice of opposition to Williams' company to abandon use of the phrase, prompting this statement from Williams:
"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."
In response, will.i.am tweeted, "I am not suing @Pharrell & I never was."
In a statement to the BBC, his lawyer, Ken Hertz, added, "We think their proposed trademark is too close to our registered and common law trademarks. They disagree. … We hope to work out a sensible compromise that will allow both parties to move forward without unnecessary acrimony."
As a member of The Black Eyed Peas, will.i.am has sold more than 31 million albums and won seven Grammys.
Williams, a member of the Grammy Award-winning duo The Neptunes, has teamed with such artists as Justin Timberlake, Kanye West and Jay-Z, and can be heard on Robin Thicke's new No. 1 single, "Blurred Lines," as well as Daft Punk's latest hit, "Get Lucky."