Article 28
[Land constitutions – Autonomy of municipalities]

(1) The constitutional order in the Länder must conform to the principles of a republican, democratic and social state governed by the rule of law within the meaning of this Basic Law. In each Land, county and municipality the people shall be represented by a body chosen in general, direct, free, equal and secret elections.

(…)

Article 38
[Elections]

(1) Members of the German Bundestag shall be elected in general, direct, free, equal and secret elections.