Quoting DisturbedComputer,
The whole idea (in theory anyway) of prison is that a person can be reformed. I think that basically these types of rules are saying that any convicted felon can never be reformed since they will be punished for the rest of their lives. If the courts decide that you can't be reformed, then that is what a life sentence is for.
That used to be the idea of prisons, back in the 70s. Today prisons, in the US anyway, are just for warehousing and punishing the convicted.
It's also questionable whether punishment even works--whether criminals consider the consequences before they commit a crime. Most murders, for example, are crimes of passion, committed on the spur of the moment due to raised emotions. Bank robbery is an addictive behavior, like cocaine abuse (I was told in college that bank robbery has the highest rate of recidivism). You have to think, when a person weighs the cost/benefits of armed robbery, why don't they conclude that it would pay more to get a part-time job, knowing that the average take from an armed robbery is under $1000 and the consequence could be 20 years in prison? There was an article in Freakonomics that showed crack dealers earn, on average, less than minimum wage.
To make progress in the war on crime we have to address lifestyle choices and personal responsibility. Mold young people into productive citizens. Separate out those who display dangerous behaviors for special attention. The compulsory education system provides a framework for doing this. But, the education system is based on a founding principle of preparing workers for an industrial, assembly-line, society, and it does not differentiate between the creative/artistic principle and the anti-social.
The morals of the US do not differentiate between marijuana use and crack use, where they should see marijuana use as roughly equivalent--or even preferential--to alcohol use. Marijuana abuse, even--being high all the time--is less destructive than alcohol abuse. You don't get hungover or irritated or psychotic from smoking too much weed over the weekend. We need to reevaluate our morality to pull it in line with scientific truth, and then we can work on developing a more moral populace.