Constitutional monarchy
Constitutional monarchy first emerged in England.  At first, the British monarchy was absolute.  However, the nobility under King John felt that the king had abused his power, and forced him to sign a document called the Magna Carta.  This document limited the powers of the king and made him somewhat responsible for the wellbeing of his subjects. The document, however was more focused on maintaining the ability of the nobles to have a say in what the king did.