Competency is a legal concept that refers both to a person's right and ability to manage his/her own affairs and make life decisions. A competent person is entitled to make decisions; an incompetent person has a legal representative, or "guardian," who makes decisions on behalf of the person determined to be incompetent. Adults are presumed competent while minors are presumed incompetent. The presumed incompetence of a minor can be overcome by "emancipation" or can be modified by laws pertaining to certain proceedings. The presumed competence of an adult can be overcome by special judicial proceedings to declare the person incompetent, proceedings for "interdiction", or for a "continuing tutorship". Without clear proof, adults are considered competent and able to make their own decisions.
The capacity to make autonomous decisions. Health-care professionals often run up against the difficult question of whether patients' expressed preferences represent their real preferences or are by-products of impaired reasoning, perception or judgment, due to various medical factors. Chronic conditions can make some patients unable to effectively direct the course of their own treatment or to follow necessary prescriptions of physicians, nurses, etc. Such patients may be declared "incompetent" and treated differently than others, e.g., with concern for their health overriding their expressed wishes. [See Case Studies related to Competency
Term used in legal situations where a person's competency to change a will, look after their affairs, or be tried for criminal actions is in doubt. Careful mental state testing is required, often repeated, to determine competency. In those people with problems various legal protections can be organised.