The US comedian Bill Cosby has gone on trial for sexual assault in a court in Pennsylvania. He is accused of drugging and sexually assaulting Andrea Constand in 2004.
Cosby, 79, was a beloved entertainer known for his family-friendly brand of comedy.
He arrived at a court in the Philadelphia suburb of Norristown, accompanied by actress Keshia Knight Pulliam, who played his daughter Rudy Huxtable in the US hit series The Cosby Show.
Cosby is accused of drugging and sexually assaulting Constand, a former basketball player at Temple University, at his home in 2004.
Her accusation is the only one to result in criminal charges out of dozens of similar allegations from women stretching back decades.
Cosby has denied ever assaulting anyone, saying the encounters with Constand and others were consensual.
The first witness in the trial Kelly Johnson stated that in 1996 in a Los Angeles hotel room, Cosby insisted on giving her a white pill to help her "relax" and that she later lost consciousness and was partially clothed when she awoke beside Cosby.
Johnson said she felt "underwater" after taking the pill and could not object.
"I was trying to say something," she said. "But I dont know if I was actually speaking."
The lawyers for the prosecution wanted this witness to show that there was a pattern in Cosby's behaviour that led to the alleged assault on Constand eight years later.
Cosby's lawyer claims that Cosby is a victim of false accusations and he said that Constand's initial allegations were found to be insufficient in 2005. He appealed to the jury to help him right a wrong, claiming that there were inconsistencies in her account to the police.
He said that she told police that she had not maintained contact with Cosby after the incident and Cosby's lawyer said that she had in fact called him 53 times.
The trial is expected to last two weeks.
