A lot of valid points have been brought up on both sides of this issue, with respect to how the criminal justice system works (and does not work).
It is fair to say that one could undertake to obtain a master's degree on this subject and still not cover every aspect of this. Which is why, for example, I prefaced some of my own opinions on the matter as "I do not hold with the general concept of..."
Debating any one aspect of the CJ system is an open invitation, therefore, to expound upon all the OTHER "stuff" that is messed up in some tangential fashion.
How to fix this isn't just a matter of "fixing the criminal justice system", however.
Why?
Because the whole issue with respect to the criminal justice system revolves around one key word: "criminal".
Human behavior is predicated upon individual character traits. From a psychological stand point, our core values, upon which all our behavior is based upon, is well established before we reach double digit age. From that point, we are essentially exploring the world around us based upon those core values in a fashion which further cements them in our minds. THIS IS WHY A STABLE AND WELL GROUNDED FAMILY IN THE FORMATIVE YEARS OF CHILDREN IS SO CRITICAL.
By core values, I mean behavioral and value concepts such as "honesty", "integrity", "empathy", "right and wrong", etc.
Core values, however, are NOT subject to change on a whim. This is both a blessing and a curse.
If you are an honest person (truth has a high value with you and how you interact with others) with integrity (does the right thing, even when nobody else is around to see it), then this is how you tend to view and interpret the world around you as well. You are this way, so your basic assumption is that most others also behave this was as well. This affects the way you interact with others and is typically an excellent type of person to be socially.
If you are NOT an honest person and have little integrity, this is likewise how you tend to view other people around you: your assumption is that most others are this way as well, which motivates you to assume the worst in them...and you tend to take advantage of those who are otherwise honest using their values against them.
These core values, being ingrained at an early age and constantly reinforced throughout life, DO NOT CHANGE without a deliberate, and concerted, effort on the part of the individual. And many times it take a pretty significant traumatic event to cause a person to question their core values enough to WANT to change them.
So the curse, with respect to criminals, is that their core values are NOT subject to easy change AND that change MUST COME FROM WITHIN. It cannot possibly come from without.
Which means "The System", whatever that system may be, can neither force a change, nor can they produce a reliable and predictable change EVEN FOR THOSE WHO MAY WISH TO CHANGE.
NOTE HERE:
I'm deliberately addressing criminal behavior which is "malum in se" (wrong because the behavior itself is bad/evil) as opposed to "malum prohibitum" (wrong only because the act is forbidden). (Also, keep in mind that just because a behavior is "malum prohibitum" does not mean laws about such acts are "wrong". But that's not germane at this point and would be more appropriate for another time.)
A lot of people do not understand this...that you cannot change people who do not want to be changed; that even if they DO want to change, it's not easy and they may not be able to no matter how much they might wish; that instituting ever increasing punishments will not change the underlying issue with human behavior in general and typically has the effect of increasing the cost to society in both resources and sacrificing of principles as a result, and that "The System", being designed, made up of, and run by people are ALSO subject to the full spread of human behavioral characteristics as well.
What does that last part mean?
It means that "The System" itself is just as susceptible to criminal behavior as what most people consider to be "criminals".
Only, in the case of "The System", you're talking about the full power and authority of the State itself.
THIS is the problem I have with criminalizing more and more human behavior, as well as the tendency to up the ante through ever increasing punishment. We're intentionally empowering an already hugely powerful entity, with all the same faults as any other member of humanity, and expecting it to be "perfect", "just", "honest", and of solid "integrity".