King John's predecessor's (king Richard I "the Lionheart") involvement in the Crusades and kidnapping on his way back to England, which meant extremely heavy taxation, plus the great loss of lands in France, led a great number of barons to threaten king John to rebel against him unless he agreed to make distinct concessions to each baron. Instead of addressing individual and particular concessions, king John came up with a document offering to set limits of the royal power against his noble subjects.
For the English colonies in America, Magna Carta was widely seen as an example of the crown subjects' right to curtail the power of the rulers protecting them from authoritarianism, oppression and abuse.