(Latin: Great Charter) Document guaranteeing English political liberties, drafted at Runnymede, a meadow by the Thames, and signed by King John in 1215 under pressure from his rebellious barons. Resentful of the king's high taxes and aware of his waning power, the barons were encouraged by the archbishop of Canterbury, Stephen Langton, to demand a solemn grant of their rights. Among the charter's provisions were clauses providing for a free church, reforming law and justice, and controlling the behavior of royal officials. It was reissued with alterations in 1216, 1217, and 1225. Though it reflects the feudal order rather than democracy, the Magna Carta is traditionally regarded as the foundation of British constitutionalism.