The Magna Carta established important principles of constitutional law and due process. It subjected the king to law instead of allowing him absolute power. It protected certain rights of freemen and established that no person could be imprisoned or punished without a fair trial by their peers. Over time, as the population became fully free, the Magna Carta's protections expanded to all people. It also protected the rights and liberties of the church and established rules regarding feudal obligations and taxes as well as standards for trade, commerce, and movement within the kingdom.