Insurance company Mutual of Omaha is suing Oprah Winfrey and her production company over the talk show host’s use of the phrase “aha moment.”

In February, Mutual of Omaha started using the slogan “official sponsor of the aha moment.” A complimentary website – ahamoment.com – was unveiled at the same time. Mutual saws it began researching trademark rights to the phrase in July 2008 and filed an application with the US Patent and Trademark Office in August of that year. No opposition was made to the application.

Meanwhile, Oprah Winfrey’s attorney says the talk show host has been using “aha moment” as her signature phrase. Her lawyer claims the phrase is now synonymous in the public’s mind with Ms. Winfrey. Harpo, Oprah’s production company, is claiming rights to the phrase.

Mutual filed the lawsuit on April 22^nd. It is seeking a legal declaration allowing it to use the slogan and pronouncing that Mutual has not infringed on Harpo’s or Ms. Winfrey’s alleged rights.