U.S. District Judge Tanya Walton Pratt ruled that the Indiana Department of Correction violated mentally ill prisoners' constitutional right against cruel and unusual punishment by keeping them separate from other inmates and failing to provide them with adequate treatment.

"The Court finds that mentally ill prisoners within the IDOC segregation units are not receiving minimally adequate mental health care in terms of scope, intensity, and duration and the IDOC has been deliberately indifferent," Pratt wrote.

Pratt did not mandate a remedy in her ruling Monday. Lawyers for both sides are supposed to meet within 45 days to discuss how to correct the problem.

The Department of Correction referred comment to the Indiana attorney general's office, which represented the state. A spokesman for that office, Bryan Corbin, said Wednesday that the agency will review the ruling with the Department of Correction and determine the next steps.

The American Civil Liberties Union of Indiana represented the state Protection and Advocacy Services Commission in the class action lawsuit that was filed in 2008 on behalf of the more than 5,800 mentally ill inmates in Indiana prisons. The commission advocates for the rights of the disabled.

Commission attorney David Smith said in an email that the agency "strongly agrees with the ruling."

"IPAS looks forward to working with and assisting the Court in determining an appropriate remedy to this problem which will stop the non-treatment and mistreatment of inmates in IDOC with serious mental illness now and in the future," Smith added.

A survey by the corrections agency in 2010 found that 22 percent of the 26,700 inmates in state prisons were diagnosed mentally ill. The system has two mental health units, which together have room for about 250 patients. Many of the rest are placed in segregation, kept separate from other inmates and mostly confined to their cells despite a consensus that segregation is detrimental to their condition, the order said.

Mental health care, like other medical care, is provided by a private contractor called Corizon. Spokesmen for the company didn't respond to requests for comment Wednesday.

A psychiatrist who visited the prison system's main psychiatric unit at New Castle said some of the patients there were "frankly psychotic," yet received little treatment and were inappropriately taken off medications.

"In practice, however, mental health treatment is principally limited to issuance of medication, prisoner conversations with the mental health staff, and mental health staff's response to incidents of actual and attempted self-harm," Pratt wrote in her 37-page opinion issued in federal court in Indianapolis more than a year after a July 2011 bench trial.

"The pervasive function of mental health staff within the IDOC has become a mixture of responding to crises and responding to prisoner requests to be seen," she added.

Pratt noted one instance in which a prisoner committed suicide about a week after he missed two mental health appointments — at least one because no guards were available to escort him.

Advocates say the number of mentally ill people in prison has risen over the years as states have cut budgets for treatment.

Josh Sprunger, executive director of the Indiana chapter of the National Alliance on Mental Illness, said the state corrections agency has improved its treatment of mentally ill inmates in the last decade, but more resources are needed to get people into treatment in the first place.