Bill Cosby trial: Prosecutor says 'trust, betrayal, and the inability to consent' is at heart of case

Bill Cosby offered his victim pills that he said would help her "relax" before sexually abusing her once she was incapacitated by the drug, a court heard.

The 79-year-old entertainer is charged with sexually assaulting Andrea Constand at his home in the Philadelphia suburbs in 2004.

She is one of dozens of women who have accused Cosby of sex assault but hers is the only case recent enough to be subject to criminal prosecution.

The first witness, Kelly Johnson, told the Montgomery County Courthouse in Norristown, Pennsylvania, that Cosby had given her a pill in a Los Angeles hotel suite in 1996

She said she initially hid the pill under her tongue but that Cosby checked to see if she had swallowed it.

She later woke up disoriented and partially clothed in Cosby's bed with the comedian behind her, grunting, before he forced her to touch his genitals, she said.

"I was trying to say something," she said. "I don'€™t know if I was actually speaking."

Her emotional testimony was intended to persuade jurors that Cosby demonstrated a pattern of behaviour when he allegedly attacked Constand in 2004.

The entertainer's lawyer, Brian McMonagle, claimed she offered much different details during a 1996 deposition, including that the assault occurred in 1990, six years earlier than she testified on Monday.

He also suggested she used drugs in the 1990s, which she denied, and accused her of having "selective amnesia" after she could not recall details of her deposition or her medical leave from her employer following the Cosby incident.

Earlier, prosecutor Kristen Feden said the case was about "trust, betrayal, and the inability to consent".

"This is a case about a man, this man, who used his power and his fame and his previously practised method of placing a young trusting woman in an incapacitated state so he could sexually pleasure herself, so she couldn't say no," Ms Feden said.

Cosby sat among a group of supporters – including former “Cosby Show” co-star Keshia Knight Pulliam – in the front row of the Montgomery County courthouse. Notably missing from the group was his wife, Camille Cosby.

Throughout the opening arguments, the legally blind former comedian leaned forward in his seat, listening intently.

At one point, Mr Cosby’s defence attorney, Brian McMonagle, gestured toward him.

“When you look at him, what do you see?” Mr McMonagle asked the jury. "Be the juror you would want if it was your grandfather, or your son or you."

Prosecutors meanwhile, attempted to show a darker side of the comedian, based largely on Ms Constand’s testimony about the night in question.

"The last words she remembers is, 'I'm going to let you relax,'" Ms Feden told the jurors. "And then as she went in and out of consciousness, she witnessed her body being used to sexually gratify the defendant."

Mr McMonagle, in response, attempted to cast doubt on Ms Constand’s version of events. He told jurors that the 44-year-old had changed her story multiple times, changing the date of the encounter from mid-March to mid-January, and initially claiming she had not spoken to Mr Cosby after the encounter. Mr Monagle says phone records show the two spoke 72 times after the incident.

The lawyer then relayed Mr Cosby’s recollection of the encounter: “She wasn’t paralysed. She wasn’t incapacitated. We were together. It was romantic.”

“Sexual assault is a terrible crime,” Mr Monagle added. “The only thing worse than that is the false accusation of sexual assault.”

The defence was allowed to call one additional accuser to the stand to testify. The woman, known publicly only as Kacey, claimed Mr Cosby drugged and assaulted her when she was working for his talent agency in 1996.

Kacey told the jury Mr Cosby invited her over for lunch at his hotel one day, and told her to meet him as his bungalow. When she arrived, she said, he forced her to take a pill that made her feel like she was “underwater”. Then he forced her to touch his penis.

Kacey says she reported the alleged assault to her parents, and eventually took her case to a lawyer.

"He asked me if I wanted to be followed and become tabloid fodder,” she said.

Mr Cosby’s highly-publicised trial is expected to last two weeks.