Germany is a federal state organized as three autonomous tiers: the Bund (federal government), the Länder (state governments) and the Städte und Gemeinden (municipal governments). Separation of legislative, administrative and judicial powers is a basic principle. The constitutional principles on which the state is governed – in effect the constitution – are laid down in the Grundgesetz (basic law) promulgated on 23 May 1949, the latest changes to which provided for German reunification on 3 October 1990 (see Ch. 3).