Landlover, yes, I do strongly believe that. If a person commits a crime and is sent to jail..what happens? This person commits crimes again once out of prison. UNLESS, during his/her stay in prison the mindset is changed with /therapy etc...THEN there is a chance this person stays away from crime.
So, it is not the punishment that prevents crime, but the change of mindset...which are 2 totally different things.

I am NOT saying people should not be sent to jail, the time in jail should be used to change this person's mindset effectively.