The now frail entertainer was slapped in handcuffs, and led out of court in his shirt and braces, his tie and jacket removed.
The comic once known as America's Dad for his role as wise and understanding Dr. Cliff Huxtable on "The Cosby Show" in the 1980s faced anywhere from probation to 10 years in prison after being convicted in April in the first celebrity trial of the #MeToo era.
A decade later, dozens of women came forward to say Cosby drugged and sexually assaulted them over his decades as a powerful actor and comedian.
"You rape women, Bill Cosby, so turn the insane down a couple notches".
Earlier on Tuesday, psychologist Timothy Foley, testifying for the defence, said that the risk of Cosby re-offending was "extraordinarily low".
For years, a nondisclosure agreement kept Constand and her family silent; the Cosby criminal trial provided her with an opportunity to finally reveal what took place almost 15 years ago.
A judge sentenced Bill Cosby to 3 to 10 years in state prison and classified him a "sexually violent predator". He faces up to 30 years in prison, though state guidelines suggest a sentence of one to four years. However, judges are allowed to issue sentences beyond those guidelines.
Prosecutors were seeking a sentence of five to 10 years in prison.
As the Commonwealth of Pennsylvania pointed out in their sentencing memorandum asking for the maximum prison time, "These assaults spanned decades and demonstrate an ingrained pattern of criminality". He is serving time at a state prison in Montgomery County after his sentencing there Tuesday. When O'Neill read those words in court, Cosby "grumbled in a scoffing manner", according to the Washington Post. So Mr Cosby is doing fine. The time has come.More news: Labour should consider joint leadership
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Defense lawyers had argued that Cosby be sentenced to home confinement over the 2004 assault. That didn't change until the end of the two-day hearing. They argued that Cosby should serve his time on house arrest.
Cosby's lawyers have said they will appeal the case. And he ordered Cosby to go to prison immediately.
Cosby made clear in that testimony that he had no verbal consent to engage in sexual contact with the woman, and without it, he was breaking the law, the judge said.
The punishment all but completed the dizzying, late-in-life fall from grace for the comedian, former TV star and breaker of racial barriers. "I had to watch Cosby make jokes and attempt to degrade and diminish me, while his lawyers belittled and sneered at me". He is legally blind.
Cosby must serve the minimum of three years before becoming eligible for parole.
Constand says her training as a professional basketball player had led her to think she could handle anything, but "life as I knew it" ended on the night that Cosby knocked her out with pills and violated her. He will also have to register as a sex offender because of the predator designation. When the judge questioned the usually chatty comedian about whether he understood his decision not to address the court, he audibly answered, "Yes".
The classification means that Cosby must undergo monthly counseling for the rest of his life and report quarterly to authorities. "Judgment day has come".
Cosby was convicted of drugging and raping Constand in April, after his legal team's defense that Constand was fabricating her allegations failed to win over his jury.