In 1946, Harvard Law School purchased what was thought to be a copy of the Magna Carta for $27.50, but it has been discovered to be an original document from 1300, one of only seven surviving copies. Professors David Carpenter and Nicholas Vincent confirmed its authenticity through various tests. The document asserts the principle that rulers are subject to the law, marking a significant foundation for law and democracy. The discovery is seen as a major find for Harvard, with potential high value in today's market.