For the past five decades, the American criminal justice system has relied nearly exclusively on as the mechanism for reducing and recidivism. The tough on crime era produced skyrocketing prison populations and the highest incarceration rates in the world. The goal was to punish more and more individuals and to punish them more severely.

The mantra was intuitive and logical—“do the crime, do the time” and “lock ‘em up and throw away the key.” It was not just clever slogans. Tough on crime is the brand, and we certainly delivered on the promise.

Not only was there massive capital investment in expanding prisons and jails, sentencing laws underwent radical changes including implementation of mandatory sentences, mandatory minimums, and habitual offender laws like three-strikes. In addition, the criminal law was expanded, dramatically increasing the number of behaviors for which there is criminal liability, in turn, widening the net of the justice system. The war on drugs also played a fundamental role in the expansion of American criminal justice.

Punishment has been meted out for a variety of reasons. Retribution is a common justification for tough sentences. Incapacitation, or preventing crime by keeping people in prison or jail is also a common rationale. Then there is deterrence, the idea that suffering punishment will deter an offender from reoffending.

Retribution or "an eye for an eye" is a perfectly reasonable justification for punishment. But that is not good public policy. The only utility to a retributive sentence is emotional satisfaction.

Incapacitation seems like a proper rationale, at least from a distance. The logic breaks down when we appreciate that incarcerating an offender does not necessarily eliminate the crime. Take drug dealing for example. Arresting a drug dealer simply creates a job opening for which there are usually many eager applicants. In fact, the failure of incapacitation to eliminate crime generally extends to much organized or gang-related offending.

Then there is deterrence, which again, at first glance makes perfect sense. Deterrence theory suggests that threats of punishment or actually experiencing punishment should reduce the likelihood of reoffending. Punishment, after all, has worked for us. Punishment plays a central role in socialization, learning to be civil, social beings. Therein lies the flaw in the thinking—criminal offenders are not like us. Their circumstances and experiences typically differ in fundamental ways from the non-offending population. More on this below.

We have spent $1 trillion on tough on crime and $1 trillion on the war on drugs, and these figures do not include any of the collateral social and economic costs of crime, the costs of criminal victimization, and a variety of other consequences. The total price tag, including criminal justice, drug control and the collateral costs, is estimated at $1 trillion per year.

So, what is our return on investment? What have we achieved with our nearly unilateral focus on punishment? There are several ways of looking at it, but perhaps the most direct is recidivism or reoffending. The overall recidivism rate is about 70%, meaning 70% of offenders are rearrested within five years of being released from the criminal justice system. It is important to note that recidivism is a conservative measure since it only counts those who have been caught.

Another way of assessing return on investment is to statistically estimate the impact of punishment policy on crime declines. Crime in the U.S. dropped dramatically during the late 1990s and has continued a downward trend, producing historically low crime rates today. Surely that is a result of our massive expansion of prisons and jails. Unfortunately, this is not good news either. The scientific consensus is that between 10% and 15% of the crime decline in the U.S. is attributable to punishment policy.

How did we get it so wrong? Why is it that something that is so intuitive and logical has failed to effectively reduce criminal behavior? First, the vast majority of criminal offenders who enter the justice system are disordered. About 60% have at least one mental health problem. Eighty percent have a . Neurodevelopmental and neurocognitive impairments are common.

Between 50 and 60 percent of offenders have had at last one , and the relationship between poverty, and neurocognitive impairment is well established. is quite common, especially the coincidence of substance use disorders and mental health and neurocognitive problems.

The failure to adequately fund public health has resulted in the criminal justice system being the repository for many disordered individuals. Since we do little to address and mitigate these disorders in the justice system, offenders often decompensate. We release them to essentially no safety net in the community.

There is nothing about prison or jail that makes one mentally healthy. Incarceration does nothing to address or substance dependence. Punishment does not mitigate neurocognitive impairment or the effects of trauma and exposure to poverty.

The great irony of the past 50 years of U.S. criminal justice policy is that we could not have intentionally designed and built a better recidivism machine than the one we have.