I'll speak on behalf of the one case for which I was subpoenaed. Ironically, it was almost 20 years after I worked at the Ottawa-Carleton Detention Centre. We take our clinical notes, and somehow they ended up in court during the hearing of a dangerous offender application. There were some notes taken about violence in the family, and it turned out that the victim had been a repeat offender. Also, the person who perpetrated the offence had re-victimized this individual repeatedly over the years.
Basically I was called upon to testify about the veracity of the clinical assessments that were done at a point in time to establish a pattern of criminality over a period of time.