The Magna Carta, sealed in 1215, is significant in limiting the powers of the monarchy and establishing the principle that everyone, including the king, is subject to the law. It introduced key concepts like due process and trial by jury, which served as the foundation for modern legal rights. The Magna Carta aimed to protect the barons' feudal rights against the arbitrary power of King John of England; however, its impact resonated beyond feudal society. Over time, it became a symbol of liberty and justice, influencing later constitutional documents, including the United States Constitution, by promoting the idea of a government accountable to its citizens.