Very true. It alone tells us nothing except that, not knowing the cause of this conviction rate, you must accept any plea bargain whatever it is.

To get a better understanding we would have to ask whether persons convicted under even the most careful trials (death penalty cases) are later exonerated eg https://www.aclu.org/dna-testing-and-death-penalty

We might also ask whether jurors enter the courtroom convinced the defendant is guilty before the trial even starts. Even here it might a coincidence: the defendants are always guilty anyway so the prejudice of the juries is irrelevant. Or we have to convince ourselves that prejudiced jurors always become open minded somewhere between voir dire and jury instruction. I suggest the later is not too believable and the former outright disturbing.

We would have to explain why federal courts have significantly lower conviction rates than lower courts by saying something like lower court prosecutors prepare their cases better or federal judges are significantly more lenient. Intuitively neither explanation seems very satisfying.

Finally we'd have to explain how charges that a DA is willing to drop during a plea bargain are then proven beyond a reasonable doubt at trial and explain how such a system, however money saving, has anything to do with justice.

Ideally, given that the number of innocent people jailed is not zero, we'd determine objectively and openly what the number is and whether we are satisfied with that rate.

1. It doesn't tell you at all that you "must" accept a plea bargain. It very well may tell you that you should bluff and proceed to trial so the prosecutor will drop your case in order to preserve his conviction rate.

2. Again, the metric is too coarse. It's not a random representative sampling of all accused criminals who make it through a full trial - the prosecution is like a football team that has the power to call off the match at any point up until the last minute if it looks like they might lose. We shouldn't be surprised that they tend to win when they choose not to do so.

3. This is well-studied and very intuitive: the more serious (and newsworthy) the charges, the more personal and political pressure to pursue a case, even a marginal one. You don't consider this possibility when speculating why federal courts have lower conviction rates.

4. A bargain requires both sides to give something up - if the prosecutor would only let you plea to the charge/punishment he thinks you'd get at trial no ones would ever plead out!

1. DA's do not drop cases after the defendant refuses a plea bargain, it is so rare as to be effectively nonexistent. Not only that, defense attorneys almost always advise their clients to take the plea bargain because they too know the chances at trial are effectively nil (and because public defenders have far smaller budgets than prosecutors). So to reject a plea bargain the defendant will also almost always be going against the advice of counsel.

And even if there was no possibly of conviction at trial, then how is it just to try to jail the accused anyway with a bluff and threat? Presumably the DA alone has decided the defendant is guilty but believes the trial system is broken so has taken it on himself to try to incarcerate the accused.

Yet all other western nations have far greater restrictions on plea bargains, the UK disallows plea bargains all together. Yet their societies have not collapsed nor become overrun with violent crime.

2. The DNA testing of death row inmates is indeed biased but not in direction you imagine. Many states simply do not allow DNA tests of convicted persons solely because it would reopen too many cases. Likewise is is also necessarily limited to those for which DNA evidence exists.

But even if the aclu testing were 100% biased toward exoneration and even if every single innocent person has now been exonerated by it, both of which are impossibly unlikely, it still means at least 17 innocent people were on death row. Even at that rate there is a far higher percentage of innocent people on death row than citizens murdered in the street. By orders of magnitude.

Even if it were just 17, it means there were more innocent Americans on death row than have died in terrorist attacks this entire decade. If we know there are terrorists in the world then we should at least be aware there is something wrong with parts of the trail system.

4.>if the prosecutor would only let you plea to the charge/punishment he thinks you'd get at trial no ones would ever plead out!

This is why it is done not why it is a good thing to do. We would never justify torture on the grounds it gets more defendants to plead out. So the question is, where is the line of too much coercion and is it currently crossed. I'd suggest where one draws that line is influenced buy whether you're already convinced every accused person is guilty and all the expense of trials is really just a waste of money.