The Magna Carta, is a legal charter, originally issued in the year 1215. The Magna Carta required King John of England to proclaim certain rights, respect certain legal procedures, and accept that his will could be bound by the law. It explicitly protected certain rights of the King's subjects, whether free or fettered, allowing appeal against unlawful imprisonment.
The Magna Carta was arguably the most significant early influence on the extensive historical process that led to the rule of constitutional law today in the English speaking world.
An A3 size poster showing the Magna Carta with colourful shields around the text and the seal of King John.