The significance of the Magna Carta, signed in 1215, lies in its role as a foundational document in the history of constitutional law. It established the principle that the monarchy was subject to the rule of law rather than absolute power. The Magna Carta introduced key concepts, such as due process and the idea of individual rights, which later influenced legal systems in many democratic societies. Its legacy can be seen in subsequent historical documents, including the U.S. Constitution and the Universal Declaration of Human Rights, underscoring its enduring impact on governance and civil liberties.