The man charged with the murder, Duane “Keffe D” Davis, is not accused of firing the fatal shots, but of arranging the murder.
In Nevada, where the trial is being held, even someone who helps another person commit a murder can be convicted of the crime.
Davis has previously spoken about his role in the murder in an autobiography, among other things, but his lawyers say what was written was fabricated. Davis denies any wrongdoing.
The trial is expected to last a month and will begin in earnest on Monday.
It was on September 7, 1996 that Tupac Shakur, who was travelling in a car with record label boss Suge Knight, was shot dead at an intersection in Las Vegas.
