Final answer:
The English Magna Carta and the American Constitution both incorporate the legal principle of due process, securing a free man's right to a lawful judgment by peers.
Step-by-step explanation:
The legal principle present in both the American Constitution and the English Magna Carta is the principle of due process. This principle ensures that a free man cannot be penalized except through a lawful judgment by his peers, or according to the law of the land. It laid the groundwork for the Fifth and Sixth Amendments to the U.S. Constitution, which outline due process rights and the right to a fair trial. The Magna Carta has been influential in shaping modern democratic values and legal systems, emphasizing the importance of protecting individual rights and limiting government power.