In jurisprudence, duress or coercion refers to a situation whereby a person performs an act as a result of violence, threat or other pressure against the person. Black's Law Dictionary (6th ed.) defines duress as "any unlawful threat or coercion used... to induce another to act [or not act] in a manner [they] otherwise would not [or would]". Duress is pressure exerted upon a person to coerce that person to perform an act that he or she ordinarily would not perform. The notion of duress must be distinguished both from undue influence in the civil law and from necessity.