Dynamic Logic of Power and Immunity

We present a dynamic logic for modelling legal competences, and in particular for the Hohfeldian categories of power and immunity. We argue that this logic improves on existing models by explicitly capturing the norm-changing character of legal competences, while at the same time providing a sophisticated reduction of the latter to static normative positions. The logic is shown to be completely axiomatizable; an analysis of its resulting dynamic normative positions is provided; and it is finally applied to a concrete case in German contract law to illustrate how the logic can distinguish legal ability and legal permissibility.