Weimar Constitution

The Constitution of the German Reich (German: "Die Verfassung des Deutschen Reiches"), usually known as the Weimar Constitution ("Weimarer Verfassung") was the constitution that governed the Weimar Republic (1919-1933). The constitution technically remained in effect during the Third Reich from 1933 to 1945.
The German state's official name was "Deutsches Reich" until the adoption of the 1949 constitution. 
Origin.
Following the end of World War I, a German National Assembly gathered in the town of Weimar, in the state of Thuringia, in January 1919 to write a constitution for the "Reich". The nation was to be a democratic federal republic, governed by a president and parliament.
The constitution was drafted by the lawyer and liberal politician "Hugo Preuss", who was then state secretary in the Ministry of the Interior and later became Minister of the Interior.