On 15 June 1215, King John of England set his seal to Magna Carta — the "Great Charter" — at Runnymede beside the River Thames, under pressure from rebellious barons who had captured London.
The document established for the first time that the king was subject to the rule of law, protecting freemen from arbitrary imprisonment and guaranteeing access to justice. Though annulled by Pope Innocent III within weeks and revised many times, Magna Carta became a foundational legal text.
Its legacy reaches forward eight centuries: it directly influenced the English Bill of Rights (1689), the United States Constitution and Bill of Rights, and the Universal Declaration of Human Rights (1948). Clause 39 — *"No free man shall be seized, imprisoned... except by the lawful judgment of his peers"* — is the ancestor of habeas corpus.