No freeman shall be taken or imprisoned, or be disseised of his freehold, or liberties, or free customs, or be outlawed, or exiled, or any other wise destroyed; nor will we not pass upon him, nor condemn him, but by lawful judgment of his peers, or by the law of the land. We will sell to no man, we will not deny or defer to any man either justice or right.
That clause (naturally, repealed in the UK) is still on the books in New Zealand today. Its a bit tattered, with the passage of asset forfeiture and refugee detention and the abolition of jury trials for most crimes, but its still there as a reminder that the government must act within the law. 800 years on, we should be strengthening these provisions, not repealing them.
As for the UK, the British government appears to want to celebrate 800 years of freedom by repealing their major legislative guarantee of it, the Human Rights Act. Which tells you just how far from Magna Carta they've strayed. 800 years ago, a group of barons claimed freedom from an over-mighty King at swordpoint; now its time for the people of the UK to save it from their over-mighty Parliament.