The significance of the Magna Carta in limiting the power of King John was profound, as it established the precedent that the monarchy was not absolute. Signed in 1215, the Magna Carta introduced fundamental principles of due process and the rule of law, asserting that even the king was subject to the law. This document laid the groundwork for modern democratic governance by promoting the idea of accountability and protecting certain rights. Its legacy influenced future constitutional developments and remains a symbol of the fight for liberty and justice.