A federal judge has approved an agreement designed to improve conditions in the maximum security facility that houses Mississippi’s most dangerous criminals.

The American Civil Liberties Union sued the Department of Corrections in 2005 over conditions in Unit 32 of the Mississippi State Penitentiary at Parchman.

Opened in 1990 at the sprawling prison in the Mississippi Delta, Unit 32 houses nearly 1,000 convicts, including 65 on death row. For years, the unit was notorious among inmates and deplored by activists who said violence and chaos were a detrimental way of life.

The agreement, known as a consent decree, was approved Thursday by U.S. Magistrate Jerry A. Davis. It sets specific guidelines for the treatment of mentally ill convicts, the prison’s use of force policy and the classifications of prisoners.

The agreement does not end the lawsuit immediately, but could be the first step if conditions improve during an “indefinite” monitoring period, said Margaret Winter, associate director of the National Prison Project of the ACLU.

Winter said the new guidelines are some of the most progressive prison changes in the country and be could used as a model for other states.

“There are still problems in Unit 32, but there have been such dramatic and profound changes in the past several months that there is now hope,” Winter said in a statement. “Unit 32 is a safer and more humane place for prisoners and for prison employees too, thanks to the hard work of all the parties in this case.”

Corrections Commissioner Chris Epps said many of the conditions in the agreement have already been implemented. Virtually all inmates were locked down 23 hours a day when the unit first opened, but now hundreds of them are allowed out of their cells for various activities, Epps said.

“We’re going to continue to move forward and make Mississippi corrections second to none in the country,” Epps said. “It’s our goal everyday to try to rehabilitate these inmates and make them better when they leave than when they came in.”

Among requirements in the agreement are:

— Mentally ill prisoners are not to be held in Unit 32 longer than 14 days.

— Those with severe psychiatric problems are taken to another prison where they “can receive the full range of appropriate treatment programs.”

— Inmates who need intermediate psychiatric care would be housed in a newly created “Mental Health Step-Down Unit” at Parchman staffed by at least one full-time psychologist.

— Inmates won’t be put in the restrictive administrative segregation classification without the approval of key officials.

— Gang members would not be put in administrative segregation based solely on their affiliation with a gang.

— At least 41 new security cameras should be put in Unit 32 for a total of 341.

— All uses of force must be approved and videotaped.