EDITED TO ADD: To note I do agree with you that what if jail/prison is not a deterrent then we are doing it wrong. To some extent this is a true statement. It has been shown that some collateral consequences of punishment can actually lead to increased crime. A collateral consequence being one that is not handed down by a judge but is the result of another law, policy, regulation, etc.. For example, if you are arrested for DWI the judge may sentence you to 30 days in jail. The collateral consequence is that your driver's license may be suspended by the Department of Motor Vehicles.
If you are arrested and convicted of a felony drug charge, serve your time, and get out a collateral consequence can be that no one will hire you because of your conviction. Many states, counties, and cities are starting to realize this actually creates more crime and are passing Ban the Box laws that prohibit asking about criminal convictions on job applications and delay background screening.
"the studies reviewed do not
provide a basis for inferring that increasing the severity of sentences generally is capable of enhancing deterrent effects."
I find it very disturbing that this is not included the basis of legislation and investigated further.
I think the telling statement in the whole report is:
"Research to date generally indicates that increases in the certainty of punishment, as opposed to the severity of punishment, are more likely to produce deterrent benefits."
I am not saying that plea deals are all bad or that they should be eliminated. I think they serve a purpose with first time offenders or to secure testimony in cases where there are significantly bigger stakes. But some plea deals are just absolutely absurd and destroy the certainty of punishment. If people knew that there were guaranteed consequences I think we could reduce jail sentences to some extent. Instead we have increased jail sentences because we have increased the plea deals. What used to be a guaranteed 30-day sentence now has turned into 90-days because with the plea deal and good time the person will only serve the original 30 days.
http://www.sentencingproject.org/doc/deterrence%20briefing%2...
EDITED TO ADD: To note I do agree with you that what if jail/prison is not a deterrent then we are doing it wrong. To some extent this is a true statement. It has been shown that some collateral consequences of punishment can actually lead to increased crime. A collateral consequence being one that is not handed down by a judge but is the result of another law, policy, regulation, etc.. For example, if you are arrested for DWI the judge may sentence you to 30 days in jail. The collateral consequence is that your driver's license may be suspended by the Department of Motor Vehicles.
If you are arrested and convicted of a felony drug charge, serve your time, and get out a collateral consequence can be that no one will hire you because of your conviction. Many states, counties, and cities are starting to realize this actually creates more crime and are passing Ban the Box laws that prohibit asking about criminal convictions on job applications and delay background screening.