Kanye West has been accused of plagiarism during a hearing at the New York District Court in Manhattan.
IOF, a New Jersey group, have said that West, along with rapper Chris 'Ludacris' Bridges, stole the lyrics and beats from their song 'Straight Like That', to create the 2003 hit 'Stand Up'.
The words "like that" are at issue in the case, and appear more than 80 times in both songs.
In the IOF track, the phrase "straight like that" is used, while in the Ludacris tune, the words "just like that" appear.
Both Ludacris and West - who co-produced 'Stand Up' - are expected to testify at the trial, BBC News reports.
Christine Lepera, lawyer for the defendants, has already criticised the case, telling the court: "There are scores of songs out there with the words 'like that' with that type of rhythm. None of you can monopolise certain expressions."
She then went on to clap her hands to demonstrate the simple beat of both songs and that neither could claim to have an original rhythm, and asked the jurors: "Do you think your three-year-old can do that?"
'Straight Like That' was not a hit for IOF and only could be heard on a few college radio stations during 2001, whereas Ludacris' 'Stand Up' sold more than 500,000 copies.
IOF's lawyer Mel Sachs however claims that Ludacris "had access to the song on numerous occasions" and that promotional copies of 'Straight Like That' had been sent out to one of the rapper's record companies.
Sachs told the jury: "(IOF) put a lot of time and effort into doing this song and then it was taken away from them."
In order to determine liability, the trial is expected to last a week. If liability is then found, a second phase of action will occur to assess damages.