Sentence:  The <WSD>Magna Carta</WSD> harkens back to 1215 when King John of England was forced by an assembly of barons to write down the traditional rights of the country's free persons. By so doing, he bound himself and his heirs to grant "to all freemen of our kingdom" the rights and liberties described in the great charter, or Magna Carta. Each subsequent ruler did the same. The 1297 Magna Carta represents the transition from a brokered agreement to the foundation of English law, upon which U.S. law is based. 
Meaning of the word marked with <WSD> tags:  A charter granted by King John to the barons at Runnymede in 1215, which is one of the bases of English constitutional tradition; a physical copy of this charter, or a later version.