(Reuters) - Attorneys for Bill Cosby outlined their grounds on Tuesday for appealing his sexual assault conviction, citing what they called errors in legal procedure that may have biased the jury and warrant a new trial for the once-beloved comedian.

FILE PHOTO: Actor and comedian Bill Cosby leaves the Montgomery County Courthouse after his first day of sentencing hearings in his sexual assault trial in Norristown, Pennsylvania, U.S., September 24, 2018. REUTERS/Jessica Kourkounis

The 81-year-old performer, best known for his role as the lovable family man and physician on the hit television sitcom “The Cosby Show,” was found guilty by a Pennsylvania jury in April of drugging and sexually assaulting a onetime friend in 2004.

It marked the first such criminal conviction of a celebrity accused of sexual misconduct since the #MeToo movement that has brought down dozens of powerful, privileged men in American media, politics and business since the autumn of 2017.

In September, the trial judge, Steven O’Neill, designated Cosby a “sexually violent predator” under Pennsylvania law, requiring the entertainer to register as a sex offender for life, and sentenced him to a term of three to 10 years in prison.

Cosby, who is married, has insisted all along that any sexual encounters he had were consensual. He was found guilty on three counts of aggravated indecent assault.

In an eight-page filing laying out the basis of their appeal, Cosby’s lawyers focused on several instances they said introduced bias into the trial, including the judge’s refusal to excuse a juror that the defense argued was unable to be fair and impartial.

The defense asserted that the juror in question had stated an inclination to believe Cosby guilty at the outset of the trial, and that fellow jurors were never interviewed to determine whether they had heard the comment or were swayed by it.

In addition, according to the filing, O’Neill failed to recuse himself or disclose a biased relationship with Bruce Castor, a former Montgomery County district attorney with whom defense lawyers said the judge had a confrontation.

Cosby’s lawyers have argued that Castor promised in 2005 that Cosby would not be prosecuted if he agreed to sit for a sworn deposition in a civil suit brought against him by his accuser, former Temple University administrator Andrea Constand.

That deposition, in which Cosby acknowledged giving sedatives called Quaaludes to young women for purposes of having sex with them, was unsealed a decade later, and Castor’s successor, District Attorney Kevin Steele, cited it as a crucial piece of evidence when criminal charges were brought.

The judge should not have allowed Cosby’s civil deposition testimony about Quaaludes to be introduced in his criminal trial, the defense said, arguing it was not relevant to Constand’s allegations and was highly prejudicial because it included statements regarding the illegal act of giving a narcotic to another person.

Cosby’s attorneys also faulted the judge for allowing prosecutors to call as witnesses other accusers whose allegations, the defense argued, were too remote in time and too dissimilar to Constand’s allegations.

Moreover, the defense asserted that a prosecution expert who testified relied on hearsay evidence of about 50 additional women who had leveled sexual misconduct allegations against Cosby.

Under the state’s appeals process, the trial judge will write an opinion by explaining his reasoning for the rulings the defense has challenged, and the matter will ultimately be decided by Pennsylvania’s appellate-level Superior Court.

A representative for the prosecution did not immediately respond to a request for comment on the filing.