The US houses the highest proportion of its people in prison of any country, as Adam Liptak discusses thought provokingly. As expected, this appears to reduce the crime rates.
How much suffering should the guilty endure for a given reduction in suffering of the innocent? I think a 1:1 ratio maximum- that is, it doesn't matter who suffers. Suffering should be minimised, even if that means the innocent suffer instead of the guilty. Punishment should only be to prevent greater suffering.
Liptak also draws attention to the relationship between more democratic appointment of judges in the US and harsher punishment, as people demand fierce retribution. I suspect demand for escalating punishment is a result of fear and angry desire for revenge, rather than widespread consideration of mechanism design for minimising harm, or anything mildly reasoned. I don't think society should be allowed to inflict harm on its members arbitrarily like this. Should judge appointment be less democratic then?
Perhaps, but this decision can (and should?) only be reached through other democratic decision making. This is the same problem as arises everywhere. The public, through democracy, interferes with people where it has no right to, but the extent to which citizens should be able to interfere with one another through democracy hasn't been agreed, and so must rely on democratic negotiation.