Cosby in sworn testimony admitted he gave the now-banned sedative Quaalude to at least one of his accusers and to unnamed others.
His lawyer interfered before he could answer deposition questions in 2005 about how many women were given drugs and whether they knew about it.
Lisa Bloom, lawyer for model Janice Dickinson, who contends she was drugged and raped, said: “If today’s report is true, Mr Cosby admitted under oath ten years ago sedating women for sexual purposes.
“Given that, how dare he publicly vilify Ms Dickinson and accuse her of lying when she tells a very similar story?”
The Associated Press (AP) had gone to court to compel the release of a deposition in a sexual abuse lawsuit filed by former Temple University employee Andrea Constand – the first of a cascade of lawsuits against Cosby that have severely damaged his image as doting TV father Dr Cliff Huxtable on The Cosby Show from 1984 to 1992.
His lawyers objected to the release of the material, arguing it would embarrass him. Ultimately, a judge seized on Cosby’s public moralising as he unsealed portions of the deposition that had been filed in court.
“The stark contrast between Bill Cosby, the public moralist and Bill Cosby, the subject of serious allegations concerning improper (and perhaps criminal) conduct, is a matter as to which the AP – and by extension the public – has a significant interest,” US District Judge Eduardo Robreno wrote.
Cosby, 77, has been accused by more than two dozen women of sexual misconduct in episodes dating back more than four decades. He has never been charged with a crime, and the statute of limitations on most of the accusations has expired.
The entertainer settled Ms Constand’s lawsuit under confidential terms in 2006. Even the judge never saw the settlement terms, although the documents show that Cosby at one point offered the accuser an “educational trust” fund.
Ms Constand’s lawyer said she consented to be identified although she did not want to comment.
Cosby’s lawyers insisted during the deposition that two of the accusers knew they were taking Quaaludes from the comedian, according to the documents.
Nevertheless, lawyers for some of the numerous women suing Cosby seized on the evidence as powerful corroboration of what they have been saying all along, that he drugged and raped women.
“The women have been saying they’ve been drugged and abused, and these documents appear to support the allegations,” said lawyer Joe Cammarata, who represents accuser Therese Serignese, one of three women suing Cosby for defamation in Massachusetts. She has also agreed to have her name published.
Celebrity lawyer Gloria Allred, representing other women, said she also hopes to use the admission in civil court cases against the comedian.
Cosby, giving sworn testimony in the lawsuit accusing him of sexually assaulting Ms Constand at his home near Philadelphia in 2004, said he obtained seven Quaalude prescriptions in the 1970s.
Ms Constand’s lawyer asked if he had kept the sedatives through the 1990s – after they were banned – but was unable to get an answer due to objections from Cosby’s lawyer.