"Forensic psychology" sometimes conjures images of crime scene investigations or criminal profiling amongst the lay public. However, the reality of the discipline is considerably more mundane. Forensic psychology exists at the interface between psychology and law. It involves the use of psychological principles to assist with legal and administrative decisions. While the evaluation of things like competency to stand trial, criminal responsibility, diminished capacity, and sex offender risk may most frequently be thought of in association with forensic psychology, the truth is that many other types of evaluations are most appropriately considered to be forensic. These include, but are not limited to, mental health evaluations of personal injury, disability, fitness for duty, competency to manage one's own affairs, parental fitness, factors related to the credibility of abuse allegations, and competency to testify. Forensic psychology sometimes applies traditional psychological knowledge and sometimes applies knowledge specific to the specialty area. It may sometimes follow a layperson's perception of common sense, but research sometimes proves that "common sense" to be dead wrong.
To appropriately understand forensic psychology, it is helpful to draw contrasts between traditional psychology and forensic psychology. Even mental health providers sometimes blur the lines between the two in ways that create ethical problems and malpractice exposure. Some distinctions between the two are as follows: