[marcus_holmes]

In the UK that would probably be the Magna Carta [0] which is a written document that constrains the monarch's power, and the monarch was the state at that time (1215).

[0] https://en.wikipedia.org/wiki/Magna_Carta

[mathiaspoint]

That's my point though. The monarch has so little power now it's irrelevant and the democratic government is out of control.