You may well be right, I've not read my copy of the Magna Carta for a while, I must admit. On the other hand, you could be totally wrong, as the MC was nothing to do with the common man, but was worded to allow the barons and lordly landowners more freedomes to raise their own taxes.
Might you be thinking of the shot-down in flames and ignored 1689 Bill of Rights? The one that says that every Protestant man should have a gun?
tac