The International Criminal Court (ICC) Prosecutorial Strategy 2009–12 reaffirmed the commitment of the Office of the Prosecutor (OTP) to positive complementarity. The Prosecutor recognised the inability of the ICC to deal with all cases of mass atrocities and the importance of relying on national systems if international criminal justice is to be effective. The article first proposes a two-pronged approach to complementarity that distinguishes between its legal and policy dimensions. On the basis of the analysis of the situations in the Democratic Republic of Congo, Uganda and Colombia, it will be argued that the OTP has taken controversial decisions from the viewpoint of complementarity stricto sensu and positive complementarity that may undermine filling the impunity gap as well as the legitimacy of the ICC. Attention is then drawn to the common substratum of the ad hoc tribunals' completion strategy and positive complementarity. It is explained how the experience of the completion strategy offers a valuable cluster of lessons to be applied within the spectrum of positive complementarity. In concluding, the article suggests measures for the execution of positive complementarity and the Law Enforcement Network, with the intention of optimising efforts and resources within the ICC system.

The transfer of intermediate and lower rank indictees from the International Criminal Tribunals for the Former Yugoslavia and Rwanda to competent national jurisdictions is a central component of the so-called completion strategy. When the ad hoc Tribunals contemplate the referral of a case, however, they find themselves hemmed in from two sides. On the one hand, a decision to refer a case will appear justified only if there are strong reasons to believe that national proceedings will be conducted in accordance with international due process standards. On the other hand, the risk that national authorities deny or minimise the responsibility of transferred indictees must be avoided. These two exigencies were given positive expression in the Rules of Procedure and Evidence of both Tribunals, under Rule 11bis. This paves the way for a comparison between Rule 11bis case law and human rights jurisprudence concerning potential violations. For the purposes of this article, comparative analysis provides the basis for asserting that, when the ad hoc Tribunals decide whether or not to refer a case under Rule 11bis, they are bound by human rights standards which go beyond the right to receive a fair trial and are stricter than those normally applicable to a state which is about to extradite or expel an individual.