Psychologists are Ph.D.'s. Psychologists tend to have greater expertise in psychometric testing such as the MMPI or Rorschach tests. There are other practitioners of psychotherapy such as licensed clinical workers and marriage, family and child counselors. Psychiatrists attend four years of post-graduate education following medical school in order to become board eligible. Approximately half of psychiatrists who have completed their training go on to become certified by the American Board of Psychiatry and Neurology.
Forensic psychiatry is the application of medical mental health expertise for legal purposes.
This is distinguished from correctional psychiatry which is the practice of clinical psychiatry in a prison or other correctional facility. There is a subspecialty examination of the American Board of Psychiatry and Neurology called Special Qualifications in Forensic Psychiatry. At this time there are only a few hundred psychiatrists nationwide who have taken and passed this examination of which Dr. O'Brien is one. A forensic psychiatrist may deal with mental health issues related to either criminal or civil issues. An example of the former would be examination of a defendant for insanity or incompetence.