The requirement of psychiatrist's and psychologist's cooperation with the prosecution authorities in addressing the defense of duress/compulsion and necessity

Three elements - legal, physical and mental – are required to commit a crime. The mental element or guilty intent must be proved by the prosecution. Commitment of crimes under duress and necessity causes not to form the required mental element. This is where the defendant claim that he/she was not consent and has not free will in committing the crime. Considering the circumstances and personality affecting the free will is of much importance. This is a comparative – analytical library study. To do so, after collecting related books, articles and codes they were compared and analyzed. The survey results that the defense of duress and necessity are accepted in both Iran’s and common law systems and if established, is a complete defense. Human being is always the source of duress, while circumstance is the source of necessity. Based on the differences in physical, mental and feeling features, the impact of duress and necessity are different on people. Duress if proved, spoils criminal and civil liability. In common law, contrary to Iran, the defense of necessity if valid, will spoil both criminal and civil responsibility. Individual differences and personality distinctions influenced by duress and necessity are so important that to apply criminal justice the prosecution officials must have psychologists’ and psycho rapists’ scientific comment.