Cosby is charged with three counts of aggravated indecent assault for allegedly drugging and sexually assaulting former Temple University employee Andrea Constand in January 2004 at his mansion in Elkins Park, Pennsylvania. He has pleaded not guilty to all charges, and has repeatedly denied similar claims from other women. Aggravated indecent assault carries a potential maximum sentence of 10 years in prison.
On Monday morning, assistant District Attorney Kristen Feden presented the prosecution's opening statements to presiding judge Steven O'Neill, in which she stressed that the case is about "trust, betrayal and the inability to consent."
"When you think whether or not he knew what effect those pills would have on Andrea, I would submit that he did," Feden stated. She went on to present the possibility that the actor's status as a public figure has the potential to skew public perception, arguing, "Our society celebrates [celebrities] to the point that they become gods. …Because of that, we think we really know them."
Cosby's defense attorney, Brian McMonagle, staunchly denied all accusations presented against his client, and presented the case that the claims made about Cosby were patently false.
"The only thing that is worse than [sexual assault] is the false accusation of sexual assault," McMonagle said, adding that a false allegations can "destroy a man's life."
Addressing the jury -- which is made up of seven men and five women -- McMonagle said, "Try to be the juror that you would want if it was your grandfather or your father or your son or you sitting over there. No distractions! Be that jury."
The first witness to present testimony was Kelly Johnson, one of multiple women who claim to have been drugged and sexually assaulted by Cosby over the last four decades.
According to Johnson's testimony, after meeting Cosby in 1990 and striking up a friendly, fatherly friendship, she alleges that, in 1996, Cosby offered her a pill during a private meeting at his bungalow and sexually assaulted her. She says she was scared and did not consent.
While recounting the alleged incident, Johnson broke down in tears. She went on to say that she didn't go to the police at the time because, "I was afraid."
The defense called into question the validity of Johnson's testimony upon cross-examination. McMonagle questioned her reported timeline, supposed inconsistencies with a deposition based on a lawyer's notes from 1996, and her claim that she was not a social drug user at the time of the incident.
"You, never having done drugs, took a pill out of a man’s hand, who was in a robe, and took it? That’s your sworn testimony?" McMonagle asked.
Cosby is not on trial for any allegations made by Johnson. Her testimony was presented by the prosecution in an attempt to establish an alleged pattern or history of behavior. Cosby has previously denied Johnson's claims, and all other claims made against him.
Pulliam -- who played one of Cosby's daughters, Rudy Huxtable, on The Cosby Show from 1984 to 1992 -- spoke with reporters during a recess and opened up about why she was attending the first day of the trial.
"I came to support [Cosby] because this is where you hear the facts. This is where the truth happens," Pulliam, 38, stated. "Ultimately, it's easy to support someone and to be in their corner when things are great, when things are good. But...true family, friendship, integrity is how people show up and support when things aren't looking so great, when they aren't shining."
In an exclusive statement to ET on Tuesday, Pulliam made it clear she doesn't "condone or support sexual assault."
"As a woman, mother, Spelman College Graduate & champion of empowering girls thru my non-profit Kamp Kizzy, I in no way condone or support sexual assault," the statement read. "At the same time, I believe you are innocent until proven guilty. This is one of our fundamental rights under our Constitution. There is a difference between opinions and facts."
"The man that the world is painting Mr. Cosby to be is simply not the man I know or have ever experienced," she added. "I am showing up in the manner I would hope my loved ones would show up for me, if the shoe was on the other foot. Mr. Cosby is still a person, father, son & husband. This is a horrible situation for all parties. Now it is up to the jury to decide. I trust that the jury will make the right decision after hearing, reviewing and deliberating the evidence."
Earlier in the day, before proceedings kicked off, Pulliam was seen walking with Cosby into the courthouse. The pair appeared to be in good spirits. Cosby later thanked Pulliam for her support on Twitter, writing, "Thank you to Cliff and Claire's 4 year old daughter (Rudy) and the Brilliant Spelman Alumnus."