In those days, before the Church of England existed, excommunication was a terrible penalty. The mere threat of it often caused people to change course.
The Magna-Carta barons remained undaunted. The "Great Charter" is the product of their defiance. (Be sure to use the zoom feature to closely examine this ancient document. Click here to read an English translation.)
Four original copies of the Magna Carta still exist. Two are kept at the British Museum in London; one is located at Lincoln Cathedral (once the tallest building in the world); and the fourth is at Salisbury Cathedral.
For Great Britain, Magna Carta is Statute Number One.