The Constitution of the German Empire (German: Verfassung des Deutschen Reiches) was the basic law of the German Empire. It came into effect on 4 May 1871 and lasted formally until 14 August 1919. Some German historians refer to it as Bismarck's imperial constitution (German: Bismarcksche Reichsverfassung, BRV).
The Constitution created a federation (federally organised national state) of 25 German states under the permanent presidency of Prussia, the largest and most powerful of the states. The presidency (Bundespräsidium) was a hereditary office of the King of Prussia, who had the title of German Emperor. The emperor appointed the chancellor, who was the head of government and chairman of the Bundesrat, the council of representatives of the German states. Laws were enacted by the Bundesrat and the Reichstag, the parliament elected by male Germans above the age of 25 years.