The cases presented were selected because they illustrate a point of law, contain some unique psychological feature, or have an unusual resolution. The overall intention of the presentation of the cases is to demonstrate how a psychologist becomes a necessary resource for addressing certain legal issues. A number of the cases reviewed focus upon the use of the psychologist as a resource in determining cognitive and behavioral competency related to a particular legal issue. The cases described address competency in the areas of standing trial, handling one's own affairs, understanding a colloquy, understanding Miranda rights, signing a confession, standing trial as an adult, release from confinement, and release on bail. Cases also explore the determination of competence of a witness, competence of lawyers, and competence in the performance of military duties. Other cases consider the issues of fitness for prison, police screenings, the ability to fake the results of a lie detector test, and determining fitness for probation and parole. Psychological studies of criminals are also included. Six references and a subject index are provided.