Liman Center Research in Spotlight as States Advance Solitary Confinement Bans


As New York State banned long-term solitary confinement this month and Connecticut considers a similar measure, research by the Arthur Liman Center for Public Interest Law at Yale Law School has contributed by documenting that the use of solitary confinement remains widespread throughout the United States.

“State and federal legislatures across the country are recognizing their vital role in bringing to an end the profound isolation of people held in detention,” said Judith Resnik, Liman Center Founding Director and Arthur Liman Professor of Law at Yale Law School. “Our data illuminate how much needs to be done.”

Beginning in 2012, the Liman Center has worked with the Correctional Leaders Association (formerly, the Association of State Correctional Administrators), an organization of directors of state and federal prisons. Liman and the Correctional Leaders Association have together produced the only national, longitudinal database on the use of solitary confinement around the United States. This data includes the number of people held in isolation in the United States and the conditions in which they live.

The most recent report, released in September 2020, is based on data from the summer of 2019, before COVID. At that time, an estimated 55,000 to 62,500 prisoners in the United States were held in isolation for an average of 22 hours a day for 15 days.

The Center cited this research in testimony submitted in March to the Connecticut legislature, which is considering a bill that would largely end solitary confinement in the state. The Center was one of about 130 individuals and groups commenting on the bill, developed by Stop Solitary CT.

“The use of solitary confinement that we documented represents thousands of hours, days, months, and years of unnecessary human suffering,” the testimony notes. A recent firsthand account of solitary confinement published in The New York Times cited the Liman 2018 report.

For the 2020 report, 39 state prison systems provided data on 825,473 prisoners. These states reported housing a total of 31,542 individuals — or 3.8 percent of the total prison population in those jurisdictions — in solitary confinement. Across the set of 39 states, percentages of the prisoners held in isolation varied from 11 percent to zero. And in a shift from prior reports, four states said they no longer keep anyone in those conditions.

The report, available online, provides insights into the race, ethnicity, gender, and age of people held in solitary. The report also outlines some of the conditions in solitary confinement.

Among the report’s findings:

  • Black women made up a larger percentage of women in solitary confinement than white women.
  • Jurisdictions described more than 3,000 people in solitary confinement as having serious mental illness.
  • Nearly 3,000 people — or 11 percent of all the people for whom statistics were provided — had been kept in solitary confinement for more than three years.

A report overview and previous years’ reports are available at