Answer:
The Magna Carta
Step-by-step explanation:
This was written as a way to give some of the power to the people after King John failed to rule well. It is said that when the king was forced to sign the document, he only had 7 knights that were still loyal to him.
Monarchs after him tended to ignore the Magna Carta when they wanted to and to differing degrees. Some followed it, others did what they wanted, and some regularly followed it but would break the rules too.
Another fun fact, during the world wars, the magna carta was actually stored in the US because Britain feared that it would be damaged or if they lost the war it would be destroyed.