O'Neill denied the prosecution's request to submit those testimonies of "prior bad acts" before Cosby's first sexual assault trial in June 2017.
The defense disputed Constand's testimony at last year's trial that he assaulted her at his suburban Philadelphia home in January 2004, when she was a Temple University women's basketball executive and he was a powerful Temple trustee.
Montgomery County District Attorney Kevin Steele argued that Cosby's new representation from outside the state of Pennsylvania should not be allowed to defend Cosby, arguing they didn't entirely follow the Pennsylvania rules of professional conduct since beginning to represent Cosby in the last eight months.
A judge has denied requests from Bill Cosby's lawyers to throw out his sexual assault case.
O'Neill put Cosby's lawyers on notice after they falsely accused prosecutors of hiding or destroying evidence in his sexual assault case.
The accusers are needed to show Cosby "systematically engaged in a signature pattern of providing an intoxicant to his young female victim and then sexually assaulting her when she became incapacitated", Assistant District Attorney Adrienne Jappe said.
Bill Cosby's lawyers want his sexual assault case thrown out, arguing that telephone records, travel itineraries and other evidence show the alleged incident couldn't have happened when prosecutors say it did. The judge called the allegation serious but says he's reluctant to break up Cosby's legal team with his retrial looming. He has said the encounter was consensual.
As part of the Constand civil lawsuit, Cosby gave a deposition where he admitted to giving women quaaludes before sex, and this deposition was widely circulated after it was unsealed because of a First Amendment request from the Associated Press.
Only Constand and one other woman, Kelly Johnson, were allowed to testify at Cosby's original trial.
At the same time, they argued jurors should hear about Cosby's secret settlement with the woman he's accused of molesting, aiming to portray her as a money-grubbing liar.
O'Neill said that due to the volume of evidence he must review, it was doubtful he would decide on Tuesday whether to allow testimony from the 19 additional accusers.
Cosby and his lawyers didn't comment as they left the courthouse after court adjourned for the day.
"He said January 2004, but now he's saying, 'Oh, I was mistaken, '" O'Neill said, suggesting that Constand should not be locked into the date she says Cosby assaulted her.
Cosby was arrested on December 30, 2015, meaning any encounter prior to December 30, 2003 would've been outside the 12-year statute of limitations.
A smiling, laughing Cosby arrived at court in Norristown, Pennsylvania, minutes before the scheduled start of the second day of a pretrial hearing.
Bliss argued Cosby could not get a fair trial because the prosecution did not investigate Jackson's claim properly and should dismiss the trial.
It was kept out of the first trial, but Mr. Cosby's team now seems willing to admit its discussion.
Monday's hearing comes less than two weeks after the death of his 44-year-old daughter from kidney disease.
The defense withdrew the allegation days later after his former lawyer confirmed he knew that the prosecution interviewed the woman before Cosby's first trial. According to the AP, the fallen television star is seeking to stop some of his accusers from being allowed to testify at his April 2nd criminal retrial.
But defense lawyer Kathleen Bliss asked O'Neill to reconsider that ruling Monday.
They're also trying to insulate Constand from what a prosecutor called "inevitable attacks" on her credibility.