Criminal Injustice: Is abnormal non-sustainable?

We at SustainZine look for things that are abnormal, things that are so inefficient and clearly irresponsible that they should be categorized as non-sustainable. We think the Criminal Justice system in the USA qualifies and non-sustainable.

Question, what is a "normal" rate of incarceration for you citizens? And if you are a way out-of-control outlier to the other developed countries, does this represent non-sustainability.
That is, if you don't put anyone in jail, are you leaving your citizens to be rampaged by mobs and vigilantes? If you have far more people in jail than any other developed country, is this non-sustainable. When does it fully represent a "broken" system of (in)justice.

Our sister site ScenarioPlans.com (or DelphiPlan.com) talks about the US criminal system of incarceration. It is clearly broken, and totally not sane: More prisoners in US than any other country: Criminal (In)Justice Scenarios.

Here is the first paragraph:

The US has the most people incarcerated of any country in the world… Even though we only have 4.3% of the world’s population, we have more inmates -- 2.2 million -- than China (1.5m) and India (0.3m), combined (36.4% of world population)! We have 23% of China’s population but 40% more incarcerated. We have almost 1% of our population (0.737%) incarcerated! We have 6 times higher incarceration rate than China, 12 times higher that Japan, and 24 times the rates in India and Nigeria. That’s right, an American has a 1,200% greater chance of being incarcerated than a Japanese citizen. We have even a 20% higher incarceration rate than Russia with 0.615% of their population in (Siberian) prisons and jails.

Tell us what you think. Is this insane? Do we need to reform? What do you think could be rationally called a "sustainable" level of incarceration?