A preliminary hearing was set for January 14.
The charge, a second-degree felony, stems from an alleged sexual assault in early 2004. Steele initially said the charge against Cosby was a first-degree felony, but the District Attorney's office later corrected that statement.
"Today, after examination of all the evidence, we are able to seek justice on behalf of the victim," Steele said. Prosecutors launched a new investigation into the allegations against Cosby after new information about the case emerged in July, he said. The 12-year statute of limitations to file felony charges in connection to those allegations expires in January.
According to the criminal complaint, Cosby faces three counts of the indecent assault charge: assault without consent, assault when the complainant is unconscious or unaware that penetration is occurring, and assault when the person impairs the complainant.
It was the second investigation to examine allegations that the comedian drugged and assaulted former Temple University employee Andrea Constand in 2004. Constand first accused Cosby a year after the alleged assault, but at the time, prosecutors declined to press charges.
On the evening in question, Cosby urged her to take pills that he provided her and to drink wine, the effect of which rendered her unable to move," distract attorney Steele said to reporters, later saying the pills rendered the victim "frozen," and "paralyzed." That was when Cosby allegedly assaulted her.
Legal experts said prosecuting the case will be challenging because of the passage of time. But prosecutors could persuade the judge to allow evidence of similar allegations made against Cosby by women around the country to become part of their case in Philadelphia.
"The passage of time might have had a net positive result for the prosecutors," said Barry Coburn, a former federal prosecutor who now works as a criminal and civil defense lawyer.
Under rules of evidence in Pennsylvania, prosecutors can introduce allegations brought by the other women if those allegations establish a mode of operation or pattern of behavior by Cosby. While a judge could rule against prosecutors, the process of determining whether that evidence is admissible will involve court hearings and never-before-heard testimony from the other alleged victims of the famed comedian and father figure.
"The chances that they can keep this testimony off the public record is poor because the case hinges on these other allegations," Coburn said. "This is going to be devastating to his reputation."
Before the alleged assault, "the victim came to consider Mr. Cosby her mentor and her friend," Steele said to reporters, noting that Cosby made two earlier sexual advances, both of which were denied.
After the alleged assault, Constand moved back in with her mother in Canada, whom she eventually told of the incident. They then notified Canadian authorities who notified counterparts in Pennsylvania, leading to the initial investigation that led to no charges, prosecutors said in a press release.
In October, Constand sued the former prosecutor who declined to charge Cosby a decade ago for defamation. The suit accuses former Montgomery County, Pennsylvania, district attorney Bruce L. Castor Jr. of using Constand as "collateral damage for his political ambitions." Castor, a Republican, unsuccessfully campaigned to regain his old District Attorney position. He lost the November election to Steele, after a campaign season that heavily focused on the Cosby allegations.
Castor said in an interview earlier this year that he thought Cosby "probably did do something inappropriate," but that "thinking that and being able to prove it are two different things."
An attorney for Constand commended the "professionalism" of prosecutors in a brief statement issued to reporters on Wednesday, after the charges were announced. The statement also expresses "appreciation" for the "consideration and courtesy" extended to Constand during the investigation. "In that this matter is now being pursued in the criminal justice system," the statement concludes, "we will not comment further."
Gloria Allred, an attorney representing 29 women who have accused Cosby of assault, told MSNBC that the charges against the comedian the "best Christmas present" many of her clients "have ever received."
Prosecutors took a second look at Constand's allegations this year, based on "new information that came to light in July of 2015," Steele said. After establishing that the statute of limitations had not yet expired for the alleged 2004 assault, the investigation was reopened.
Cosby acknowledged in a 2005 deposition that he intended to give drugs to young women with whom he wanted to have sex. His admission that he obtained Quaaludes to use on women was contained in a 10-year-old deposition given by the legendary comedian in a civil lawsuit filed by Constand.
US District Judge Eduardo Robreno unsealed those records for the first time in July, writing that Cosby "has donned the mantle of public moralist and mounted the proverbial electronic or print soap box to volunteer his views on, among other things, childrearing, family life, education, and crime. To the extent that Defendant has freely entered the public square and 'thrust himself into the vortex of (these public issues),' he has voluntarily narrowed the zone of privacy that he is entitled to claim."
In an extensive investigation of Cosby by Washington Post reporters last year, several of his accusers said Cosby had a ready supply of pills. One woman said Cosby had a special briefcase with compartments for different pills. She said he told her the pills would help her "relax."
Victoria Valentino, a former Playboy model who alleged that Cosby drugged and assaulted her in 1970, said news of the criminal case is vindication for the women who have come forward with similar allegations.
"We knew what the truth is and we made a decision to stand our ground and we were not going to be silenced anymore," said Valentino, now a nursing school instructor in California who first told her story to The Post last year. "We were not going allow the shame and the blame and the humiliation and the fear of the crime that was perpetrated on us to silence us any longer."
Documents containing excerpts of the deposition appeared to support one element of the repeated allegations of sexual assault lodged against Cosby, some of which date to the late 1960s. Dozens of women have said Cosby sexually assaulted them after they were rendered unconscious or incapacitated by unknown substances.
However, Cosby did not admit to any criminal activity in the documents; the deposition was taken as part of a lawsuit filed by Constand, who said Cosby molested her. The lawsuit was settled out of court.
Cosby has denied all wrongdoing - and, until Wednesday, had never been charged with a crime; he and his representatives have steadfastly denied the assault claims by a succession of women. He said in his 2005 deposition that he gave Constand only three half-pills of Benadryl, an over-the-counter allergy medication.
In a deposition taken in late September 2005, Cosby was asked by Dolores M. Troiani, Constand's attorney, "When you got the Quaaludes, was it in your mind that you were going to use these Quaaludes for young women that you wanted to have sex with?"
Cosby replied: "Yes."
Cosby's lawyers said he did not have Quaaludes during the time he knew Constand and did not give them to her.
Cosby admitted in the deposition to getting seven prescriptions for Quaaludes in the 1970s. He also admitted to meeting one unidentified woman after a performance in Las Vegas and offering her the drug. "I give her Quaaludes. We then have sex," he said.
According to the DA's office, Cosby faces a maximum penalty of 5-10 years, and a US$25,000 fine.
