Léon Duguit (born February 4, 1859, Libourne, France—died December 18, 1928, Bordeaux) was a French jurist, one of the most revolutionary legal thinkers of his generation, who elaborated an influential natural-law philosophy.
Duguit studied law at the University of Bordeaux and was appointed professor in the faculty of law at Caen in 1883. In 1886 he returned as professor to Bordeaux, where he became dean of the faculty of law and remained until his death.
Duguit had a significant influence on French public law. Discarding traditional theories that looked upon law as deriving from the authority of the monarch or the state, Duguit instead found the basis of law in the fact that humans are social animals endowed with a universal sense or instinct of solidarity and social interdependence. Out of this sense came the recognition of certain rules of conduct as essential for living together in a society. In Duguit’s view, the state is not a sovereign power but is an institution that has arisen out of the social needs of humans; governments, like individuals, are bound by the rules of law derived from social necessity. Duguit’s work remains an important and original contribution to legal thought. One of his most important works is Traité de droit Constitutionnel, 5 vol. (1921–25; “Treatise on Constitutional Law”).