Cover: Criminal Justice Policies Toward the Mentally Retarded Are Unjust and Waste Money

Criminal Justice Policies Toward the Mentally Retarded Are Unjust and Waste Money

Published 1997

by Joan R. Petersilia

Research Brief


Persons with mental retardation are a small but increasing portion of the population under the jurisdiction of the criminal justice system. In most states, that system makes little or no allowance for the disabilities of such offenders, resulting in dispositions that are inequitably harsh and in all likelihood costlier to the public than need be the case. Those are the conclusions reached by Joan Petersilia in a recent review of the evidence bearing on this issue. Petersilia is a researcher in RAND's Criminal Justice Program and Professor of Criminology at the University of California, Irvine. This brief summarizes the basis for her conclusions.

Persons with mental retardation are usually defined as those with an IQ below 70, but practically speaking, such persons can be described with fair accuracy as having a childlike quality of thinking, coupled with slowness in learning new material. Mentally retarded persons have little long-term perspective and little ability to understand the consequences of their actions. They are usually followers and are easily manipulated. (The mentally retarded are not typically mentally ill; mental illness can strike persons at any level of intellectual functioning.)

Inequity at Every Step

The preceding characteristics help explain why persons with mental retardation are disproportionately represented at each phase of criminal justice processing:

  • Arrest and Prosecution. Persons with mental retardation often make no attempt to disguise what they have done. In fact, in trying hard to please authority figures, they may confess to what they have not done. And they have little protection against this, as they often waive their Miranda rights (without understanding what they are doing).

  • Pretrial Incarceration. Bail is typically available only for those with jobs or with stable living situations; mentally retarded persons often lack both.

  • Plea Bargaining, Court Processing, and Sentencing. Since persons with mental retardation tend to provide more incriminating evidence to prosecutors than other defendants, they are less successful at plea bargaining. When they go to trial, their testimony may be viewed as less credible because aggressive prosecutors can make them appear unreliable. Probation is commonly granted to persons with higher intelligence and greater educational and work achievement, so the mentally retarded serve jail or prison sentences at higher rates.

  • Incarceration, Parole, and Recidivism. Persons with mental retardation are typically housed with the general prison population, where they are often abused or victimized. They tend to rely on physical responses to physical threats and are thus often reclassified to higher security levels. That, together with a poor record of program participation and an inability to impress parole boards on interview, makes them less likely to be granted parole as early as the average inmate. Once released, mentally retarded persons often have problems meeting their parole requirements and find it more difficult than the average inmate to get a job.

  • The net result is that persons with mental retardation are not afforded an opportunity to respond to the challenges thrown at them by the criminal justice system in a way that is functionally equivalent to that of more-intelligent arrestees. As a result of this inequity, the typical mentally retarded offender costs the public more for incarceration than does the average person convicted of similar crimes.

    A Problem Ignored

    The system fails these individuals, and thus the public, usually because it ignores them. It does not routinely identify them as mentally retarded at any phase of the process. And routine screening would be required for identification, since persons with mental retardation often try to conceal their disabilities. But even when a judge suspects a mental disability, he or she cannot usually act on this suspicion because there are few provisions to treat the retarded any differently (although many provisions target the mentally ill).

    Failure to identify persons with mental retardation makes it difficult to assess the scope of the problem. The best recent estimate suggests that mentally retarded persons make up approximately 4 percent of the prison population. Some 21,000 mentally retarded persons in California alone are on probation or parole or are incarcerated in juvenile or adult facilities — a number that would seem worthy of policy attention. Yet this population has drawn almost no scholarly, public, or policy interest.

    A few cities — Boston, Fort Worth, and Cleveland among them — do have programs that aid the transition of the mentally retarded parolee or probationer to society. And programs in New Jersey and Pennsylvania divert certain convicts to carefully supervised probation. Programs offering daily structure and work to mentally retarded participants seem to reduce considerably their rearrest rates. These efforts raise hopes for broader implementation of programs to serve this population. The objective of such programs is not to excuse mentally retarded offenders from punishment but to recognize their special needs and, in doing so, foster their return to law-abiding behavior and save taxpayers money.

    Incentives for Improvement: Savings and Litigation

    The potential for savings may be recognized by considering the record and promise of intermediate sanctions as applied to the general offender. These sanctions are community-based programs that are tougher than traditional probation, but less stringent and expensive than prison. They have been tried in all states but have not shown the savings anticipated. The main reason is that offenders given intermediate sanctions are those who would have served the least time in prison anyway and would thus have incurred the lowest prison costs; low costs mean low potential for savings.

    Offenders with mental retardation represent a more promising target group for intermediate sanctions. For the reasons mentioned above, they tend to serve long sentences relative to others who commit similar crimes. And, because it appears they can be safely supervised under intermediate sanctions and their recidivism reduced, costs can be lowered further.

    If the potential savings are not enough to induce states to change the way they handle offenders with mental retardation, they are likely to face litigation under the Americans with Disabilities Act. That federal law, signed in 1990, bans discrimination based on disability. In reports interpreting the act, U.S. Department of Justice staff have made it clear that states cannot ignore the needs of prisoners with mental retardation. They must instead review all prison programs to ensure that they are accessible to and usable by disabled inmates. In California, private organizations have already filed a class action lawsuit1 against the governor and the state department of corrections to force compliance with the act. This case could set precedent and, if nothing else, should considerably raise the profile of the issue.

    Whether states take action to save money or to comply with a court order, much more needs to be known to ensure that the actions taken will serve justice, the taxpayer, and the offender with mental retardation. All prisons will have to begin assessing incoming inmates for mental disabilities, as those in Texas now do, so the scope of the problem can be discerned. And more information will be needed regarding the characteristics of offenders with mental retardation and their crimes, how persons with mental retardation become involved in the criminal justice system, and who provides advocacy services on their behalf, among other things.


    • [1] Clark and Woods v. California is now proceeding through the U.S. District Court, Northern District of California.

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