Now, the department has agreed to meetings with the nonprofit law firm.

"The California Department of Corrections and Rehabilitation is working with the Prison Law Office on the issue they identified," CDCR spokesperson Terry Thornton said.

Citing departmental records, the Prison Law Office reported more than 75 episodes during a six-month period last year when prisons imposed severe restrictions on all inmates of a particular race in response to incidents that were "reported to involve only a small number of identified inmates of that race …"

The average length of the lockdowns during the period was 109 days, according to the letter. During lockdowns, inmates are confined to their cells and usually unable to participate in programs.

Prison Law Office attorney Rebekah Evenson said the state's readiness to discuss lockdown policies was a positive first step.

"We're hoping for a constructive dialogue with the department that will lead to policies that treat prisoners as individuals and not according to racial stereotypes," Evenson said.

The group is seeking a binding agreement with the department to end "racially-discriminatory lockdowns and implement a formal policy of conducting individualized assessments of all prisoners on lockdown status as soon as possible after the incident causing the lockdown." 

Terry Thornton said CDCR policies prohibit the use of lockdowns to target specific racial or ethnic groups "unless there is a legitimate penological interest in doing so."

Thornton said she was unable to discuss the policies in detail because they are part of a confidential section of the CDCR's operations manual

However, Thornton said the public will be able to read and comment on the policies later this year when the department begins the process of writing them into CDCR regulations .

The Prison Law Office has won major legal battles with the Department of Corrections on issues ranging from health care to excessive force.