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. Not the Magna Carta barons. 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 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.