How the International Criminal Court Upholds the Rule of Law: Exceptions to the Principle of Complementarity and Ne Bis In Idem


A key principle of the rule of law is that the law be applied equally and fairly, such that neither the individual nor the State is above the law. This is partly achieved through judicial systems that are independent, impartial, open, transparent, and provide a fair and prompt trial.  These characteristics extend beyond the confines of national borders into the international sphere. From an international law perspective, the International Covenant of Civil and Political Rights requires that criminal proceedings be conducted by an ‘independent and impartial tribunal’ (Article 14). International jurisprudence has defined some of the features of ‘independence and impartiality’ as including security of tenure;[1] freedom from political influence/bias,[2] and respect for the separation of powers between the executive and judiciary.[3]

The International Criminal Court (ICC) is one example of an international judicial body that aims to promote the rule of law, both in it’s own jurisdiction, and indirectly in nation states. It strives to establish the rule of law by ensuring the most severe crimes of concern to the international community do not go unpunished.  The ICC promotes respect for international law without usurping a State’s sovereignty to investigate and prosecute crimes committed by its own nationals or on its own territory. This is achieved according to the principle of complementarity.


The principle of complementarity, enshrined in Article 1 of the Rome Statute (the Statute governing the ICC) recognizes that the ICC will not unduly supersede or replace national courts. On the contrary, the ICC defers to the courts of national jurisdiction. Article 17(1)(b) provides that where a ‘case has been investigated’ and the ‘State which has jurisdiction over it has decided not to prosecute’, the case will be inadmissible in the ICC unless it can be shown that the State was ‘unwilling or unable’ to genuinely prosecute the accused. The principle of complementarity under Article 17 places significant emphasis on the validity of national judicial systems and their proceedings according to the standard of the rule of law. By examining the “genuineness” of national investigations and proceedings, the ICC upholds the rule of law internationally with the view to end impunity. The term ‘genuinely’ in Article 17 was chosen in preference to other terms, such as ‘effectively.’ The latter could have given the impression that a case would be admissible if the national system was, for example, proceedings more slowly (less effectively) than the ICC, or if the ICC could do a better job. Rather than competition for jurisdiction, the principle of complementarity aims to encourage and facilitate genuine national proceedings.

As a consequence of complementarity, the number of cases that reach the Court should not be a measure of its efficiency. On the contrary, the absence of trials before this Court, as a consequence of the regular functioning of national institutions, would be a major success.

Statement by Mr. Luis Moreno-Ocampo, June 16, 2003 Ceremony for the Solemn Undertaking of the Chief Prosecutor International Criminal Court

There is a presumption that the ICC will be precluded from taking any action when a State has a functioning judicial system. Only if there is no relevant State criminal investigation or prosecution underfoot, or the national courts are clearly “unwilling or unable” to do justice, may the Court investigate the crime(s) (Article 17 & 18). Further, where a case has been investigated by a State, or where both an investigation and trial have been completed, the principle of ne bis in idem applies. Ne bis in idem protects a person from being tried before the ICC for conduct which has already been tried by the ICC itself or by other courts in previous proceedings (including national proceedings). Exceptions include where the purpose of the national proceedings was to shield the person from criminal responsibility; where the proceedings were inconsistent with an intent to bring the person to justice; or where the judiciary lacked independence (Article 20(1) & (3)).

When does the ICC intervene?

The ICC has considered when a national judiciary is “unwilling or unable” to genuinely investigate or prosecute grave crimes. “Inability” may be due to a total or substantial collapse or unavailability of the national judicial system, such as where the State is unable to obtain the accused or the necessary evidence. More pertinent to discussions about the rule of law and abuse of power is where a State is “unwilling”.

Unwillingness may be manifested through the granting of excessively generous amnesties or pardons with the practical effect being that the perpetrators are shielded from prosecution.  Attempts to shield the accused are often due to the accused’s links to the political party that has retained power in a post-conflict State. Other manifestations of unwillingness are suspiciously slow proceedings or a clear lack of independence of the judiciary. The ICC is not precluded from exercising jurisdiction where a State’s unwillingness is clear, albeit implied (i.e. not expressly made). Indeed, in the case of  The Prosecutor v. Germain Katanga, the ICC was interested in whether ‘a State makes clear its unwillingness to bring the accused to justice’,[4] and express statements were merely one manifestation of unwillingness.

The ICC seeks to balance the importance of state sovereignty with upholding the rule of law and seeking justice for the victims of war crimes. Truth and Reconciliation Commissions play an important role in aiding this process.

National Truth and Reconciliation Commissions

It is somewhat ambiguous whether National Truth and Reconciliation Commissions constitute investigations/proceedings. These quasi-judicial bodies may lack various judicial features given that the very nature and purpose of these bodies is often to encourage perpetrators to tell the truth by shielding them from criminal responsibility. Such extrajudicial restorative and transitional justice mechanisms can fail the stringent tests contained within Article 17(1) and Article 20(3), even though they offer invaluable forums for social healing.  The recovery of victims requires the restoration of the socio-political fabric; retributive prosecutions alone may not suffice to address the needs of victims in a post-conflict society. Nevertheless, the rule of law may still operate in conjunction with Truth Commissions. The admissibility of a case before the ICC should not undermine the continued operation of the Truth Commission for ongoing reconciliation, rehabilitation and restoration.

[1] Garcia v Peru (Inter-American Commission on Human Rights, Case No 1/95 11.006, 17 February 1995), [VI 2(a)]; Campbell and Fell v United Kingdom (Judgment) (European Court of Human Rights, Case No 7819/77; 787/77, 28 June 1984) [78]..

[2] Ibid.

[3] Bahamonde v Equatorial Guinea (United Nations Human Rights Committee, Case No 468/1991, 20 October 1993), [7.2].

[4] Prosecutor v Katanga and Chui (Reasons for the Oral Decision on the Motion Challenging the Admissibility of the Case (Article 19 of the Statute)) (International Criminal Court, Trial Chamber II, Case No ICC-01/04-01/07, 16 June 2009), [88] (emphasis added).

About the Author

Louisa Spiteri

Louisa Spiteri writes for The Institute as part of our Blog Intern program run in partnership with the International Law Committee of the NSW Young Lawyers of The Law Society of New South Wales. She is a solicitor whose legal experience spans across the Legal Advisory Section of the International Criminal Court, the Public Defenders Chambers, the Australian Human Rights Centre, an award-winning humanitarian firm, and legal research work for esteemed academics. Louisa undertook her Bachelors of International Studies combined with Law at the University of NSW. She has a passion for government accountability, the rule of law, human rights and international law.