The panel has deliberated more than 45 hours without reaching a verdict on charges that Cosby drugged and molested a woman inside his home in Cheltenham Township, Montgomery County, in 2004.
"The judge can say, 'Do you think more deliberations would be helpful?' But the judge can't say, 'How are you split?'" explained Bradford Colbert, a professor at Mitchell Hamline School of Law in St. Paul, in an interview with Minnesota Public Radio.
Each of the three counts carries a standard sentence range of five to 10 years in prison.
Jury deliberations have now lasted about as long as the prosecution and defense cases combined.
Dozens of women have come forward to say he drugged and assaulted them, but this was the only case to result in criminal charges. Judge Steven O'Neill said Friday that defense lawyers have made at least four bids for a mistrial as the deliberations have worn on without a verdict.
"I thank you from the bottom of my heart for everything you have done", O'Neill told them. They began deliberating Monday evening and have continued into Friday.
Cosby's lawyer objected in court Friday to the panel's repeated requests to review testimony, saying it suggested some jurors were trying to coerce other jurors in an attempt to bring an end to the deadlock.
"The jury can always write a note to the judge what the vote is, but the courts prefer not to have that information", Slotnick says.
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Through its lengthy deliberations, the jury made six requests asking to rehear sections of testimony, including statements from Constand, deposition testimony from Cosby and statements from police who spoke to the pair about the night the comedian allegedly sexually assaulted her.
Benedict Morelli, a prominent trial attorney who represented Tracy Morgan in the case against Wal-Mart, told Business Insider that the fact that the jurors asked the judge to clarify the concept of reasonable doubt means that it's likely one or two jurors are holding out against finding Cosby guilty rather than the other way around.
The jury, bused in from the Pittsburgh area, has paused a half-dozen times to revisit key evidence, including Cosby's decade-old admissions that he fondled Constand after giving her pills. She got into a heated argument with Cosby supporters outside the courthouse after the jury announced they were deadlocked.
It's alleged he sexually assaulted college administrator Andrea Constand at his Philadelphia-area home in 2004, after giving her pills she said left her unable to thwart his advances.
But he said he no longer had them when he met Constand in 2002 at Temple University.
His spokesman Andrew Wyatt said Cosby "wasn't bothered" by the disturbance.
"Very often, juries that are deadlocked are able to come to a verdict on Friday afternoons or the day before a holiday", says NY criminal defense lawyer Stuart Slotnick, who's been following the trial. During that "aggressive conversation", Gianna Constand testified, Cosby discussed in graphic detail the physical contact he had with Andrea, apologized and claimed he felt "perverted". "I've seen deadlocks in even the simplest of misdemeanor cases".
They've deliberated almost 40 hours since getting the case. He has said it was Benadryl, a cold and allergy medicine.