An investigation of the California prison system revealed troubling numbers of female inmates who had been sterilized without their consent, in addition to many other breaches of protocol.

A report released on Thursday by the California State Auditor examined 144 cases of tubal ligations (more commonly referred to as having one’s “tubes tied”) performed on imprisoned women over the course of eight years.

“Some of the inmates were sterilized unlawfully, and there were certain safeguards that were designed to limit those occurrences, and those failed,” Margarita Fernández, the auditor’s chief of public affairs, tells TIME.

Among the 144 cases, 39 sterilizations were performed without the inmate’s lawful consent. In another 27 cases, the inmate’s physician did not sign the form that confirmed two key components of consent: first, that the patient was mentally competent and understood the lasting effects of the procedure, and second, that the required waiting period had been satisfied.

State law requires that at least 30 days and no more then 180 days must pass between the inmate signing over their consent and undergoing the procedure. In some cases, this waiting-period window was not observed properly, Fernández said. One sterilization took place 196 days after consent was given.

The auditor called on the Medical Board of California to investigate the 39 cases in which consent was not obtained, and asked the California Department of Health to investigate physician and hospital practices. The move comes after the Center for Investigative Reporting broke a story that reported over a hundred cases of unlawful sterilization.

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