»Lex Posterior Principle and Constitutional Law«: The lex posterior principle resolves conflicts in law by reference to the criterion of time: the later law prevails. Reducing this principle to a tool of legal interpretation does not do justice to its constitutional dimension. This work situates the derogation rule within the order of the German Basic Law and locates its roots in the legal order’s openness to change – a possibility that is warranted by the democracy principle and allows to navigate tensions between continuity and flexibility in the exercise of state authority.