Live by the jury, die by the jury. As Americans, for good or ill, we don't just make policy at the ballot box.
Whenever a jury turns loose an alleged murderer, I never blame the jury - I blame the prosecutor. I blame the lack of trust in the criminal justice system and the police. But most of the time the case gets made, even on circumstancial evidence. I'd wager far more juries convict people than turn them loose, even if our popular culture makes it seem the other way around.
Back in the day, juries were compromised, and routinely fixed by the laws of the time. Minorities could not get a fair trial with an all white jury and the prejudice of the day. It was problematic when juries would throw out the facts and decide cases based on prevailing racial attitudes. (#KilledMockingbirds)
But sometimes, a jury's behavior might surprise you. Like the time that jury in Montana refused to even hear a prosecutor's case because of the small amount of marijuana involved in the defendant's arrest.
By not even hearing the case, they didn't hear about the defendant's full criminal history. But he wasn't on trial for his prior deeds, he was on trial for a 1/16 ounce of controlled substance. Hearing the charges, the jury didn't see fit to waste their time on the matter, leaving a stunned prosecutor, defense attorney, and judge even as they voted themselves out of the courtroom en masse.