Bill Cosby faced the start of a sentencing hearing on Monday at which a judge will decide how to punish the 81-year-old comedian who blazed the trail for other black entertainers and donated millions to black causes but preyed on at least one young woman and perhaps many more.

Cosby was the first celebrity to go to trial in the #MeToo era and could be the first to go to prison — perhaps for the rest of his days — after being convicted in April of drugging and sexually assaulting former Temple University employee Andrea Constand at his suburban Philadelphia home in 2004.

Daniel Filler, dean of Drexel University's Kline School of Law, said judges can’t help being influenced a little by the “optics” of a case — that is, how it is going to look to the public.

In this instance, “the judge is going to get flak”, he said. “The judge is going to get less flak if they see Bill Cosby walk out in cuffs.”

Attorney Gloria Allred (centre) with her clients, Bill Cosby accusers Chelan Lasha (left) and Lise-Lotte Lublin, takes questions from reporters at the Le Meridien Hotel in Philadelphia on Sunday. AP

At the end of the potentially two-day hearing, Montgomery county judge Steven T. O’Neill could sentence Cosby to as much as 30 years in prison or send him home on probation. The state guidelines for someone like Cosby, with no prior convictions, call for about one to four years behind bars.

“Obviously, the allegations are serious, and, except for his age and poor health, would normally warrant some jail time,” said Samuel Stretton, a veteran defense lawyer not connected to the case.

Cosby is legally blind and uses a cane, something his lawyers are certain to point out along with his achievements and philanthropy. Prosecutors hoped to call some of his other accusers to paint Cosby as a sexual predator deserving of prison.

Whatever the sentence, Cosby is likely to be deemed a sexually violent predator and will have to undergo monthly counseling the rest of his life, in prison or out. Neighbours and schools will be warned he is living nearby.

In the years since Constand first went to police in 2005, more than 60 women have accused Cosby of sexual misconduct, though none of those claims have led to criminal charges.

In this March 6, 1992, file photo, Bill Cosby appears on the set with Gary Gray and Jessica Vaughn during the taping of the final episode of The Cosby Show, in New York. AP

Cosby, who grew up in public housing in Philadelphia, became the first black actor to star in a prime-time TV show, I Spy, in 1965. He remained a Hollywood A-lister for much of the next half-century, hitting his peak in the 1980s with the top-rated Cosby Show as the warm, wisecracking dad, Dr Cliff Huxtable.

But behind the scenes, according to testimony, the married star sought out sexual encounters with young women, including actresses he offered to mentor, models seeking a part on his shows, and flight attendants he met in his travels. He also acknowledged obtaining quaaludes, a sedative-hypnotic drug, in the 1970s to give to women before sex.