On May 26, Chicago’s Cook County Jail appointed a clinical psychologist as its executive director. Some 25 to 35 percent of the jail’s “9,000 inmates suffer from serious mental illness, making it the largest mental health institution in the country,” Cook County Sheriff Thomas J. Dart, said in a statement last month.

Over the last few years, the Cook County Jail has experienced a spike in the number of mentally ill inmates amid deep cuts to mental health services. Activists say the selection of a psychologist is part of a growing recognition for the criminal justice system’s unsuitability for those with mental illness. Given their difficulty adapting to the violent and rigid culture of incarceration, mentally impaired inmates are particularly vulnerable. And because correctional facilities are not designed for this population, they are inflicting grievous harm on those inmates.

Statistics on the use of force by corrections staff against people with mental disabilities are lacking. But in a new report earlier this month, Human Rights Watch (HRW) released the first comprehensive review of the mistreatment and abuse of mentally ill inmates in prisons and jails across the country. The report estimates that 1 in 5 U.S. prisoners exhibits signs of serious mental illness and many more experience less severe or intermittent symptoms. Yet in the vast majority of states, prisons and jails are the biggest mental health institutions.

There are 10 times as many people with serious mental illness in prisons and jails as in psychiatric facilities, according to the Treatment Advocacy Center, a Virginia-based nonprofit group that promotes access to mental health care. A recent study by the Urban Institute, a think tank based in Washington, D.C., found that more than half of state inmates and nearly half of federal inmates have mental health problems yet only one-third of state prisoners and one-sixth of jail inmates report that they have received treatment. When treatment provided, it is often limited to medication and is not tailored to the individual mental health needs of inmates.

The prospects for mentally ill inmates were not always so bleak. The deinstitutionalization movement of the 1970s, which advocated for community-based treatment of people with mental illness, was hailed as a watershed moment for their humane care. Instead of warehousing the mentally ill in abysmal and countertherapeutic institutions whose bleak vistas now serve as the backdrop for horror movies, the government pledged to develop robust community treatment programs to enable those with mental disabilities to live in minimally restrictive environments.

But the initial promise of more humane treatment never materialized when funding and political will gave way to other priorities and social safety nets were gutted. Now the demand for community and residential mental health programs far outstrips the supply, and those seeking or requiring treatment often languish without support on the margins of society.

To make matters worse, there are few alternatives to incarceration for minor offenders whose mental illness minimizes their culpability and for whom prison will likely worsen their conditions. As a result, the U.S. effectively reinstitutionalizes the mentally disabled population it once vowed to treat humanely. Unfortunately, many mentally ill inmates now leave correctional facilities more impaired then when they entered.