Physicians in California prisons illegally sterilized at least 39 women during an eight-year period, with cases recorded as late as 2011, according to a report put out last week by the state’s own auditing office.

Cynthia Chandler, co-founder of the Oakland-based group Justice Now, which has been raising concerns about prison sterilization processes for years, said that the report’s release “feels like an incredible step and vindication for people who work toward challenging human rights abuses.”

The audit found problems in 39 cases, which account for more than a quarter of the 144 women who underwent the sterilization procedure between fiscal years 2005-6 and 2012-13. In 27 of the cases, inmates’ physicians had failed to sign the necessary consent form detailing that the patients were mentally competent, had understood the lasting effects of the procedure, and that the required 30-day waiting period after initial inmate consent was given had passed. Eighteen cases potentially violated that required waiting period, which is intended to give female prisoners time to think about their decisions before their surgeries take place. In some cases there is even evidence that doctors falsified records, claiming that the waiting period had elapsed when it actually had not.

According to the report, the federal receiver’s office, which has overseen medical care in the state’s prisons since 2006, argues it has no legal obligation of ensuring prison physicians or other employees obey the consent procedures, a claim which state Sen. Ted Lieu (D-Redondo Beach) said was “ludicrous.”

State Sen. Hannah-Beth Jackson (D-Santa Barbara), one of the legislators who called for the report, said its revelations show the problem to be “systemic” in nature and that there is now “clear proof that the prison environment is an environment where consent simply cannot be obtained in a responsible, reliable manner for these procedures.”