The Magna Carta, signed in 1215, had a profound impact on constitutional law by establishing the principle that everyone, including the king, is subject to the law. This foundational document emerged from the conflict between King John of England and his barons, who demanded limits on his power and protection of their rights. The Magna Carta introduced concepts such as due process, the right to a fair trial, and protection from unlawful imprisonment. Its legacy inspired later constitutional developments, including the English Bill of Rights and the U.S. Constitution, promoting democratic governance and individual liberties.