Duress (law Lat. durities; Fr. duresse), in law, the constraint by means of which a person is forced to act against his will. Duress is either of imprisonment, which must be either without lawful process, or by abuse of lawful process for an unlawful purpose; or it is per minas, where the compulsion is through fear of personal injury. Duress is admitted as a defence to a criminal charge only under several important restrictions. 1. It is not in general a justification for a felony, but only for the lesser offences called misdemeanor. 2. There must be apprehension of danger such as might reasonably be entertained by a person of ordinary courage; though in determining this, the age, sex, health, temperament, etc, of the person are important elements to be considered. 3. The injury threatened must be such as to endanger life or limb, and not of personal chastisement merely, or of injury to reputation or property. 4. Command by a father or master is not a justification to a child or servant for the commission of a crime; yet the wife was by the common law held to be in the power of the husband so far that what was done by her in his presence was deemed to be done under duress, and was a justification even for capital offences, except treason and murder.

This was upon the legal presumption that if the husband was present the wife acted by his coercion; still greater would be her claim to exemption if actual coercion could be proved. There was, however, a singular inconsistency in not allowing the same excuse on the ground of coercion, actual or presumed, in respect to mere misdemeanors. It has been plausibly suggested that the reason of this anomaly was that the wife was not entitled to the benefit of clergy, while the husband was so entitled; and as he could therefore escape from punishment for certain offences, but the wife was subject to the penalty, the law humanely interposed and relieved her from all legal liability in cases where husband and wife were jointly chargeable, but in which a claim to benefit of clergy was allowed, and this privilege did not apply to misdemeanors, nor to murder or treason. - As a defence to contracts, duress is admitted with much greater liberality. In general any contract entered into under duress of imprisonment, and in order to obtain relief therefrom, may be avoided for the compulsion; a reasonable fear of unlawful injury to one's person or reputation, or of destruction to one's property, may also constitute a valid defence; and in some cases it has been held that fear of unlawful imprisonment is legal duress, and that even detention of goods may be sufficient to avoid one's contract where he has no other speedy means than the giving of the contract for obtaining possession of them.