The word "diet" derives from Latin and was a common name for an assembly in medieval European polities like the Holy Roman Empire. The Meiji Constitution was largely based on the form of constitutional monarchy found in nineteenth century Prussia and the new Diet was modeled partly on the German Reichstag and partly on the British Westminster system. Unlike the post-war constitution, the Meiji constitution granted a real political role to the Emperor, although in practice the Emperor's powers were largely directed by a group of oligarchs called the "genrō" or elder statesmen.