Kanye West also co-produced the single named in the case

New Jersey group IOF say the stars lifted beats and lyrics from one of IOF's songs to produce the Ludacris and West co-written hit Stand Up in 2003.

Lawyers played both tracks to the jury, who were seen nodding their heads in time to the Ludacris record.

Both rappers are expected to testify at the trial.

Key phrase

At issue are the words "like that" which appear more than 80 times in both songs.

Ludacris appeared in Oscar-winning film Crash

However, IOF use the phrase "straight like that", while in the Ludacris song the phrase appears as "just like that".

Lawyer for the defendants, Christine Lepera, criticised the case.

"There are scores of songs out there with the words 'like that' with that type of rhythm," she said.

"None of you can monopolise certain expressions."

The lawyer said that both songs had a simple beat, and clapped her hands to demonstrate the point.

"Do you think your three-year-old can do that?" she asked jurors, suggesting that neither recording could claim to have an original rhythm.

Promotional copies

The IOF song, Straight Like That, was not a hit and only received airplay on a handful of college radio stations in 2001.

Kanye West has won six Grammy Awards in two years

However, the band's lawyer, Mel Sachs, said Ludacris "had access to the song on numerous occasions".

Promotional copies of Straight Like That had been distributed to one of Ludacris' record companies, the lawyer claimed.

IOF "put a lot of time and effort into doing this song and then it was taken away from them," he told the jury.

Sachs also noted that Ludacris' single had "catapulted" his career, selling more than 500,000 copies.

As well as rapping, Ludacris is known for his acting roles in Crash and Hustle and Flow.

West, who co-produced the Ludacris song, is one of the most popular producers and rappers in hip-hop.

His first two albums, The College Dropout and Late Registration, have sold millions of copies.

The trial is expected to last a week and will determine liability. If liability is found, a second phase will assess damages.