The Art of Forensic Psychology
When Lyle and Erik Menendez murdered their parents in California in 1989, they claimed that their father had long abused them both and that they had been acting in a protracted form of self-defense inspired by "learned helplessness." In both of their trials (two a piece), mental health professionals took part, including Erik's former therapist. There ensued a battle between experts over the psychological symptoms of a battered person, and even a criminal profiler addressed whether the crime scene manifested the behavior of planning. Those mental health experts who interviewed the brothers had to determine whether their tales of abuse were authentic or their symptoms malingered, and they had to make their findings understandable to the juries. Thus, they had to know their roles for the court system: They were there to provide expert opinion, not act as therapists. They were to evaluate the brothers' state of mind at the time of the incident, not draw legal conclusions for the jury. In the first set of trials, held at the same time in the same courtroom, both juries hung. In the second set in 1995, when the judge disallowed the battered person syndrome defense for lack of evidence, both juries convicted the brothers of two counts of first-degree murder.
Forensic psychologists must know the procedures and expectations of the court. As expert witnesses, they must be credible, competent, and prepared. They should also understand that the court prefers jargon-free assessments and objective information that directly addresses the issues at hand -- and only those issues. In fact, the legal system's approach may clash with the general attitude of psychology as a science, so those professionals who accept such cases must be prepared for some tension. For example, the court expects that people have free will and are therefore responsible for their criminal choices; psychologists view choices in a context of other causal factors. The court seeks certainty; psychologists work within probability. The court seeks brief statements; psychologists may seek to offer complex explanations.
In any event, mental health experts have a specific role in legal proceedings, directed by whoever hires them, and the most effective witnesses know what the attorneys do in an adversarial arena and how to address the fact-finders, whether judges or jury members. In general, as expert witnesses they will either offer the results of a specific assessment or findings from their own field of expertise. Let's look first at the psychological approach to evaluation.