The pioneering black comedian faces three counts of aggravated indecent assault in one of America's biggest celebrity lawsuits in years. Each charge carries a maximum sentence of 10 years in jail and a $25,000 fine.
"I wanted it to stop," 44-year-old Andrea Constand told the second day of the trial in Norristown, Pennsylvania about an evening in January 2004 at Cosby's mansion in Cheltenham, just outside Philadelphia.
Constand says Cosby, whom she considered a mentor, plied her with pills and wine before sexually assaulting her on his couch after she sought his advice about moving to Canada and switching careers.
The then-30-year-old director of women's basketball at Temple University -- where Cosby was serving on the board of trustees -- said she had asked the television star if the pills were herbal, and that he indicated they were.
"I said I trust you," she recalled saying at the time.
About half an hour later, Constand said, she had trouble talking and difficulty moving and was suffering double vision. After briefly losing consciousness, she came round as Cosby was touching her private parts, she testified.
"In my head, I was trying to get my hands to move, get my legs to move, but I was frozen and those messages didn't get there," she said, her voice breaking.
Constand's testimony is central to the case against the disgraced 79-year-old star of "The Cosby Show," which legal experts say will essentially boil down to her word against his.
Tuesday marked her first public appearance since she submitted to a deposition against Cosby in late December 2005, after waiting a year to report the alleged assault.
Smiling, dressed in a pale blue jacket and a white top, she answered initial questions from assistant district attorney Kristen Feden with a calm voice. But her demeanor changed when the testimony switched to the night in question.
"I felt really humiliated and I was really confused," she said after gathering herself together.
Cosby says he gave Constand Benadryl to relieve stress, insisting their sexual relations were consensual and accusing her of lying.
Around 60 women have publicly accused the Emmy-winning television star of being a serial sexual predator for decades, ending his career and leaving him isolated by friends and celebrities.
But Constand's allegations are the only ones to have been brought against him in a criminal case so far.
