Disgraced TV legend Bill Cosby was back in court Tuesday with his lawyers fighting to dismiss the first criminal charge filed against him among dozens of allegations of sexual assault spanning four decades.

Dressed in a suit and tie, the megastar turned pariah walked into court in Norristown, just outside Philadelphia, Pennsylvania, using a walking stick and steered by two bodyguards. His legal team says he has now lost his sight.

It marked the 78-year-old's first appearance in court since posting bail of $1 million on December 30 and since his lawyers filed a petition last month, asking the court to dismiss the charge.

They claim it violates a 2005 agreement that Cosby would never be prosecuted over allegations of assault made by Andrea Constand, a former employee of Temple University in Philadelphia.

Constand says Cosby forced himself on her at his suburban Philadelphia home in 2004. Prosecutors say he urged her to take pills and drink wine, leaving her unable to resist as he committed aggravated indecent assault.

On Tuesday, the comedian appeared in better spirits than during his bail hearing, when he walked stony-faced through the media scrum, by chatting and smiling with his bodyguards and lawyers.

Cosby's team called as a witness Bruce Castor, the former Montgomery County district attorney who reached the agreement that the actor would not be prosecuted over the alleged 2004 assault if he testified in a civil suit.

Castor told the court that Constand had "ruined her credibility" by going to a lawyer and that the civil agreement offered the best possible justice.

She gave "inconsistencies" in different accounts of what happened, he said.

"Within days, she had changed the day for when it happened from March to January. There were numerous examples of that," he added.

"The matter was resolved and I am hopeful that I had made Ms Constand a millionaire," the former prosecutor added.

If found guilty, Cosby — who has surrendered his passport to the court but has yet to enter a plea to the criminal charge — could face up to 10 years in prison and a $25,000 fine.

 STATUTES OF LIMITATION

The court will resume proceedings on Wednesday and Judge Steven O'Neill said he would like to reach a decision the same day.

More than 50 women have publicly alleged sexual abuse by the pioneering black comedian, who attained his greatest fame for his role as a lovable obstetrician and family man in the hit 1980s sitcom "The Cosby Show."

But his attorneys repeatedly deny any wrongdoing by the veteran TV actor whose career spanned four decades.

In the Pennsylvania case, they argued that an "inexcusable" 10-year delay since the alleged 2004 incident had also "greatly prejudiced Mr Cosby."

Prosecutors say the charge stems from new evidence in the case that came to light in July, prompting the reopening of the investigation.

They accuse Cosby of fondling the woman and penetrating her with his fingers.

Statutes of limitations have prevented most of the women who have accused the comedian of sexual assault from taking legal action. In the Pennsylvania case, the statute of limitations is set to expire early next year.

The accusations against Cosby have led television networks to back away from projects connected to him, and several universities have stripped him of honorary degrees.

In December, he filed a defamation suit against seven of his accusers.

In a deposition Cosby gave as part of the civil suit filed by Constand, which was settled in 2006, the actor insisted all relations with her were consensual, and accused her of lying about the assault.

"I think Andrea is a liar and I know she's a liar because I was there. I was there," Cosby said in the deposition, cited by The New York Times.

Prosecutors said the release of court documents in July and the subsequent release of the deposition had in part led to the reopening of the case.

Constand said she was willing to cooperate with prosecutors, according to prosecutor Kevin Steele.