In Assessing the Truth: How Forensic Psychiatrists and Psychologists Evaluate Litigants, Dr. Mark Levy, a Distinguished Life Fellow of the American Psychiatric Association and ADA expert writes:
Unlike a treating clinician whose mission is to alleviate suffering and, thus, when called to testify, is appropriately an advocate for his patient, the forensic psychiatrist and psychologist have a different mission: our task is to determine as accurately as possible what is objectively true with regard to diagnosis, the medical course, treatment and prognosis, based upon clinical evidence. Accurate diagnosis is all important. The other opinions such as course, prognosis and treatment flow from this.
Modern medicine is evidence-based and so too is modern forensic psychiatry. It is no longer enough for an expert to simply rely upon his authority and say, in effect, “I have been in practice for 30 plus years and have earned this and that degree and credential and honor, therefore what I say is true, is true because I say so.” Today, an expert must be prepared to answer the underlying question, “Upon what objective clinical evidence, Doctor, do you base your opinions and conclusions?”