If your metric is time spent in jail by innocent people, then the optimum is obvious: don't prosecute anyone.

That's absolutist, too. If we define a goal of 'zero jailed innocent people', even accepting it as a goal we can likely only ever asymptotically approach, then it shows an impedance mismatch between how to attain this, and the motivations of prosecutors which are not the same, but rather typically, 'show a high and increasing rate of convictions to show a toughness of crime'.

This is not to say that all prosecutors are railroading sociopaths, of course not. But there is a valid question in the sense of "should a prosecutors role be to a) see the guilty punished, or b) to see the most convictions?".

I don't disagree with any of this. My objection with this entire subthread has been the assertion that plea deals violate rights. I find that crazy. When presented with the facts of a case, a good prosecutor and defense attorney will be able to reasonably assess probabilities for the possible verdicts. Hammering out a plea that's around the average outcome can be beneficial to everyone.

I think there should be some onus on the prosecution to show (beyond grand jury levels) some more grounds that they'd reasonably win a case before being allowed to offer a plea deal.

Obviously there's a threshold - how do you do so without a 'mini trial' of sorts (which I get is part of the purpose of the grand jury)? And where the plea deal is initiated by the defendant, then this is waived.

I'm not outright against plea deals. But I do think they are massively overused here in the US, and there needs to be some safeguards that you're not shoehorning someone into something, just to get anything.