Has to do with bad crime lab evidence:

https://www.sacbee.com/news/politics-government/capitol-alert/article233375207.html

"While the San Francisco Police Department was responsible for running the lab, not Harris’s district attorney office, a court ruled in 2010 that the district attorney’s office violated defendants’ constitutional rights by not disclosing what it knew about the tainted drug evidence.

Judge Anne-Christine Masullo wrote in her decision that prosecutors “at the highest levels of the district attorney’s office knew that Madden was not a dependable witness at trial and that there were serious concerns regarding the crime lab.”