Bill Cosbyis a free man, but prosecutors are asking the highest court in the land to review his case ... claiming he was never given immunity from a PA prosecutor in the Andrea Constand case.
According to new legal docs obtained by TMZ ... prosecutors in Pennsylvania are asking the U.S. Supreme Court to look at the PA Supreme Court's ruling which overturned Cosby's conviction -- leading to his immediate release from prison.
Remember, Cosby walked free back in June after serving more than 2 years of a 10-year sentence in his sexual assault case. The PA Supreme Court ruled the conviction was bogus because Cosby had relied on an agreement with a previous prosecutor to not criminally charge him when he was deposed in the Constand case.
In new docs, prosecutors are calling on the U.S. Supreme Court to right what they say is a "grievous wrong," arguing Cosby's overturned conviction is a slippery slope that could set a dangerous precedent.
They insist Cosby wasn't given lifetime immunity from prosecution just because the former prosecutor declined to criminally charge him at the time.
The appeal is a bit of a Hail Mary on behalf of prosecutors. The U.S. Supreme Court hears less than 1% of petitions, but there's still a chance ... however slim.
Cosby's spokesperson, Andrew Wyatt, is ripping prosecutors over the appeal, saying the D.A.'s Office is "unwilling to accept its epic loss" and he's calling it a "pathetic last-ditch effort that will not prevail."