Matthew Yglesias, commenting on a man who is in jail for murder despite exculpatory DNA evidence, propounds an interesting theory:
The true limiting factor in determining how many people are in jail is the amount of space available in the jails which, in turn, is limited by the amount of money folks are willing to dedicate to prison construction and maintenance. In practice, if the jury had let this guy off the hook the space he occupied just would’ve been taken up by harsher sentences for several people convicted of lesser crimes like robbery and assault. In crime-reduction terms, the net effect of convicting any particular person — even if he’s guilty — is likely to be zero. Prosecutors would’ve just pushed for tougher sentences in plea bargain negotiations with other offenders, since they would’ve had more beds to fill.
Have there been any studies on the extent to which available jail space factors into prosecution decision-making? I can’t imagine that the correlation is especially high, particularly in cases where the prosecuting attorney is at a different level of jurisdiction than the incarceration facility. Why would, say, a local D.A. care how much room is available in a state penitentiary? For that matter, would have even know? I would think that prosecutors would be inclined to push for the maximum sentence they think they can get in every instance.
Matt also wonders what goes through the minds of juries that convict based on apparently flimsy evidence:
The evidence here isn’t so strong and I do have some doubts that the guy is guilty. But I think he’s probably guilty since I basically trust prosecutors and the police. Moreover, he’s accused of a really awful crime and crime is really awful. We can’t take the risk of letting these people out on the streets or else a bad crime situation in this country will get even worse. So let’s convict, but no death penalty.
This strikes me as quite plausible. I have sat in on a handful of trials, and the type of reasoning Matt suggests was a large thrust of the DA’s closing argument to the jury: “We have a huge problem with drugs/rape/etc. and this guy is charged with that. Drugs/rape/etc. are very, very bad. You must send a message that this community won’t tolerate drugs/rape, etc. If you don’t convict this man, you’re condoning drugs/rape, etc.” That said, in the few trials I’ve watched where I would have voted to acquit, the jury did.
