Clarifying the Principle of Complementarity: the ICC Confirms Admissibility of Case Despite Investigation by Kenya

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Chris Stephen is an associate at Volterra Fietta practising public international law. He previously worked as judicial assistant to Lord Hope of Craighead and Lord Mance in the House of Lords (now the UK Supreme Court).

It is trite to state that the jurisdiction of the International Criminal Court (“ICC” or the “Court”) is complementary to the criminal jurisdiction of national courts. Due to both reasons of respect for State sovereignty and the practical constraint of limited resources, it is first and foremost the duty of national courts to effectively investigate, prosecute and punish the perpetrators of the most serious crimes of international concern. Thus it is only when a State fails in that duty, either through an inability or unwillingness to fulfil it, that the ICC may seek to step into the shoes of that State and assert jurisdiction. This is the principle of complementarity.

However, what of the precise content of that principle? When are the investigations or prosecutions conducted by a State deemed sufficient to demonstrate willingness and render a case before the ICC inadmissable? Is this a high threshold to satisfy?

A recent decision of the ICC assists in answering those questions and adds some welcome flesh to the bones of this oft-cited principle. On 30 August 2011, in The Prosecutor v Francis Kirimi Muthaura, Uhuru Muigai Kenyatta and Mohammed Hussein Ali (ICC-01/09-02/11 OA) a majority of the Appeals Chamber (Judge Anita Ušacka dissenting) adopted a judgment dismissing an appeal brought by the Republic of Kenya challenging the admissibility of the case in light of national investigations. 


In late December 2007, widespread violence broke out in Kenya following the announcement of the result of the presidential elections held on 27 December that year. The elections saw incumbent president and leader of the Party of National Unity (“PNU”), Mwai Kibaki, in competition against the leader of the Orange Democratic Movement (“ODM”), Raila Odinga. The result which emerged, in favour of Mr. Kibaki, came after lengthy delays and widespread accusations of vote rigging. In the mass violence which ensued, over 1,200 people are estimated to have been killed.

Kenya and the ICC

Kenya signed the Rome Statute of the ICC on 11 August 1999, with ratification taking place almost 6 years later, on 15 March 2005.  On 26 November 2009, the Prosecutor of the ICC sought authorisation from the Pre-Trial Chamber to conduct an investigation using his proprio motu powers into the violence which had taken place in the post-elections period:

“I received more than 43 communications, including reports describing the alleged crimes. According to Kenyan authorities, 1,220 persons were killed. Hundreds of rapes were documented. Many more, probably thousands, were unreported. 350,000 persons were forcibly displaced, 3600 persons were injured. These alleged crimes were part of a widespread and systematic attack against the civilian population. They … are crimes against humanity.”

On 31 March 2010, Pre-Trial Chamber II granted that authorisation. On 15 December 2010, following an investigation, the Prosecutor of the ICC named six men as suspects:

  • William Samoei Ruto (suspended government minister of higher education, science and technology);
  • Henry Kiprono Kusgey (member of parliament and chairman of the ODM)
  • Joshua Arap Sang (head of operations at Kass FM radio);
  • Francis Kirimi Muthaura (secretary to the cabinet);
  • Uhuru Muigai Kenyatta (deputy Prime Minister and minister for finance); and
  • Mohammed Hussein Ali (chief executive of postal corporation of Kenya)

 The Decision of the Appeals Chamber

On 6 June 2011, Kenya filed an appeal pursuant to Article 19(2)(b) of the Rome Statute, which states:

“2. Challenges to the admissibility of a case on the grounds referred to in article 17 or challenges to the jurisdiction of the Court may be made by:

(b) A State which has jurisdiction over a case, on the ground that it is investigating or prosecuting the case or has investigated or prosecuted…”


The principal issue raised by Kenya in its appeal related to the interpretation of the words contained in Article 17(1)(a) of the Rome Statute:

“The case is being investigated or prosecuted by a State which has jurisdiction over it, unless the State is unwilling or unable genuinely to carry out the investigation or prosecution;”

Firstly, the Appeals Chamber confirmed that a State which seeks to challenge the admissibility of a case bears the burden of proof in doing so. To discharge that burden, the State in question must: “provide the Court with evidence of a sufficient degree of specificity and probative value that demonstrates that it is indeed investigating the case”. (para. 61) Furthermore, this was: “not merely a question of ‘investigation’ in the abstract, but … whether the same case is being investigated by both the Court and a national jurisdiction.” (para. 36)

This of course begs a further question; what is meant by the same case? In this regard, the Appeals Chamber emphasised that the wording of Article 17(1)(a) must: “be understood in the context in which it is applied” (para. 38). In other words, Article 17 of the Rome Statute could apply to a number of scenarios on the spectrum, ranging from preliminary rulings regarding admissibility and the Prosecutor’s decision to initiate an investigation, to cases which have developed much further. Therefore, one must have regard to the specific stage of the proceedings in question when considering the words: “[t]he case is being investigated or prosecuted”. If, for example, an investigation is only in the initial stages and no individual suspects have yet been identified by the ICC, a domestic investigation will not (necessarily) be expected to have done so either and may, perhaps, be sufficient to render a case inadmissible before the ICC. If, on the other hand, the investigation work of the ICC has become more closely delineated and possibly identified particular suspects, it will not be enough for a State to argue that is preparing to take steps or that it intends to investigate other suspects.

In the view of the Appeals Chamber, Article 19 of the Rome Statute relates to the admissibility of: “concrete cases” (para. 39). These cases are therefore framed and defined by the warrant of arrest, summons to appear or charges brought by the Prosecutor and confirmed by the Pre-Trial Chamber. Consequently, the Appeals Chamber held:

“the defining elements of a concrete case before the Court are the individual and the alleged conduct. It follows that for such a case to be inadmissible under article 17(1)(a) of the Statute, the national investigation must cover the same individual and the substantially the same conduct as alleged in the proceedings before the Court.” (para. 39)

Lastly, the Appeals Chamber was keen to emphasise that the genuineness of an investigation was an entirely separate question from determining whether there was an adequate investigation being carried out in the first place:

“For assessing whether the State is indeed investigating, the genuineness of the investigation is not at issue; what is at issue is whether there are investigative steps.” (para. 40)

One may consider this attempt to compartmentalise the contents of Article 17(1)(a) as somewhat artificial. While perhaps logically sound, in reality it is hard to conceive of the Court being able to competently decide one aspect (is there an investigation?) without at least giving some consideration to the other (is that investigation genuine?).


The situation in Kenya is the first instance in which the Prosecutor of the ICC has exercised his proprio motu powers. Kenya is also the first State to raise a challenge to the admissibility of a case. This is therefore an important and informative decision. Crucially, it further illuminates the principle of complementarity which underpins the jurisdiction of the ICC. Indeed, as the Appeals Chamber itself expressly acknowledged, this is the first occasion on which the ICC has had to rule on the issue of whether a national investigation being carried out by a State must always concern the same person(s) involved in the case before the ICC (para. 34). The Appeals Chamber has responded by answering that question in the affirmative (the decision of the dissenting judge, Judge Anita Ušacka, is yet to be filed). In so doing, it has revealed a robust approach as to what the content of a national investigation by a State must embody to render a case inadmissible before the ICC. With the Court possessing a stated determination to end impunity, this is perhaps unsurprising.

Interestingly, it should be borne in mind that this was not a decision in which the Court determined that Kenya was either: “unwilling or unable” to genuinely carry out its investigation. Rather, it was the inability of Kenya to provide sufficient evidence to convince the Court that it was investigating the same individuals now suspects before the ICC which resulted in its challenge to admissibility being dismissed. Charges hearings will now take place for all six men during September 2011.

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Steve says

September 20, 2011

Great analysis, the debate around complementarity principle has been confusing especially to states that are non-cooperative to the ICC process and this article brings this out.

Complementing a process ought to be seen in its true meaning that both the political and legal process are meeting at one point of realising justice. But where the state does not show that commitment and political will, then complementarity is compromised.