The "duty to protect" doctrine heralded by the Tarasoff decision seeks to prevent physical harm to third parties by psychiatric patients. Recent court cases have mandated the testimony of a criminal defendant's psychotherapist both about the Tarasoff warning itself and about confidential treatment information that was associated with the warning. One court further ruled that some clinical sessions were not psychotherapy and therefore were not afforded the protection of psychotherapist-patient privilege. The continuing erosion of confidentiality has resulted in psychiatrists and other mental health professionals becoming prosecution witnesses at the criminal trials of their own patients.