Cato sent me a copy of In the Name of Justice, edited by Timothy Lynch. It's not my field, so I just read Lynch's introduction. He describes a litany of ways in which our criminal justice system takes away Constitutional protection. It fails to conform to any theory of either utilitarian or retributive justice.
I wonder to what extent the practice of criminal justice in this country is centered around the issue of keeping people we consider dangerous off the streets. That might explain why we are happy with incarceration, even though we are not that committed to deterrence and we are not overly concerned with retribution. It might explain why rehabilitation is not such a priority. We have very low expectations for that you will rehabilitate, and we just want you off the streets.
I'm not saying I endorse this approach. It's highly problematic, especially when one considers the subjectivity in deciding who we want to take off the streets. I'm just saying that if you want to explain our justice system in practice, you might go with the theory that its goal is to pull people off the streets based on the judgment of law enforcement officials.