Universal Jurisdiction Meets Complementarity: An Approach towards a Desirable Future Codification of Horizontal Complementarity between the Member States of the International Criminal Court

This paper will propose a first draft provision concerning horizontal complementarity between the member states of the ICC. Firstly, the idea of subsidiary universal jurisdiction will be introduced. At its heart, the work will bring the concepts of vertical complementarity and subsidiary universal jurisdiction into relation to define a desirable future codification of horizontal complementarity. The author will focus on the following seven issues that have to be addressed during the drafting of such codification: The relationship between the actors; the legal qualification of horizontal complementarity; the underlying idea and ratio behind the concept; a positive or negative determination of complementarity; the definition of horizontal complementarity; the question who the final arbiter of a determination should be; the matter of compliance with decisions. It will be seen that Art 17 ICC Statute can serve as a useful basis of this codification but that the special relationships on the inter-state level will inevitably lead to some deviating requirements of this principle.