Simon Cowell, pop star, is accused of stealing an idea for a new U.S. television show, which is titled Million Dollar Idea.
The pair, who accuses the Idol, filed a lawsuit in a Los Angeles court alleging that the Pop Idol host had copied the entire premise of a show already being aired, and sold it as his own.
Jean Golden and Todd Walker, who claim they created the original show, have demanded an injunction and unspecified damages from Cowell and US network ABC.
"It is incredibly ironic that our show, the premise of which is to promote, protect and reward small-town American ingenuity, was itself the victim of corporate theft and greed," Golden said in a statement.
Their lawyer, Ann Marie Mortimer, said the couple devised a show of exactly the same name and concept which had run successfully for four years in Minneapolis, This is London reports.
She claimed they had pitched a detailed blueprint of the programme to ABC in 2004 as part of an attempt to develop the brand and reach a wider audience.
"It's impossible to miss the striking similarities between the two shows," she was quoted as saying by This is London. "Not only is the idea the same, this is the ultimate act of arrogance."
"(Golden and Walker) had the show copyrighted, the business plan copyrighted and the name trademarked - it's more than just an idea, it's a three season success, an established brand."
In the ABC show, contestants' ideas will be judged by a panel of three business leaders, dubbed The Millionaires.
Nine hopefuls will get $50,000 each and go through to the final, where the winner will be given $1m (Ј555,000), according to BBC.
Cowell will not present the show because of his American Idol contract with Fox TV.
Production company FremantleMedia North America is also named in the legal action.
The legal papers said: "While imitation may be the sincerest form of flattery, imitation in the form of outright copying is not flattery at all - it is intellectual property theft."
Roaring Entertainment and Million Dollar Idea's creators and hosts Jean Golden and Todd Walker say they offered the show to ABC in early 2004.
They filed the legal case in Los Angeles and are seeking unspecified damages.