With respect, it is, in my view, a mistaken understanding to say that customary international law recognises any such immunity for anyone before an international court in the exercise of criminal jurisdiction.
To begin with, the matter of immunity is governed by the terms of the treaty that Kenya and its fellow States Parties signed: the Rome Statute. All States Parties agreed in it that the ‘Statute shall apply equally to all persons without distinction based on official capacity.
In particular, official capacity as Head of State or Government [etc] shall in no case exempt a person from criminal responsibility under this Statute, nor shall it, in and of itself, constitute a ground for reduction of sentence.’
The Statute also provides that ‘[i]mmunities or special procedural rules which may attach to the official capacity of a person, whether under national or international law, shall not bar the Court from exercising its jurisdiction over such a person.’ The point of these provisions is that they guide the question of immunity for officials of a State Party, regardless of what customary international law says. [But, I discuss extensively below what customary international law really says and how it got to saying that.] It is important to stress in this connection that, contrary to the assertion in the AU press statement quoted above, it is not generally the case that incumbent Heads of State enjoy immunity from prosecution.
Kenya is one country that does not recognise immunity for its Head of State in respect of certain offences. In particular, the Constitution of Kenya does not recognise immunity even for the President of Kenya with respect to prosecutions under the Rome Statute. Notably article 143(1) recognises immunity for the President or persons performing the functions of the President ‘during his tenure.’
But, in a specific exception, article 143(4) provides that ‘[t]he immunity of the President under this Article shall not extend to a crime for which the President may be prosecuted under any treaty to which Kenya is Rome Statute, article 27(1).
Immunity for heads of State
I now turn to the argument that customary international law does not permit the trial of a sitting Head of State or of senior State officials. That proposition lacks strong support. The legal developments that make it so will now be considered.
First, the ICJ has rightly said that customary international law prevents the trial of officials of a State in the national courts of another State. But that rule does not operate when it comes to trying officials of States before international courts.
There is no precedent that supports the successful plea of immunity before an international criminal court. The point may be illustrated in this way. On the Scheveningen beach, on a warm summer day (a rare event that no one can help), any man may feel fully entitled to wear his own Speedo®. Custom may absolve him. But it is something else to say that there is — as yet — any custom that entitles the same man to dress the same way, as a lawyer, when representing clients further up the road in the courtrooms of the ICC.
Second, even the review of international legal history leaves no room at all for the proposition that a Head of State, whether still in office or out, may claim immunity before an international criminal court.
The point may become clearer with a review of the historical development of the idea of individual criminal responsibility, particularly in the manner that culminated in the norm now codified in article 27(1) of the Rome Statute. But, before delving into history, it may help to address certain provisions of the ICC basic documents that may lead to some headscratching about the question of immunity at the ICC as a matter of customary international law.
My aim in this is to address what may be a temptation to deduce official position immunity as a customary norm that applies at the ICC, at the substrate or residual level, by inferring it from nothing more than the sheer logic of verbal contamination.
This is an excerpt from presiding judge, Eboe-Osuji, public redacted version of the decision on defence applications for judgments of acquittal in the Ruto-Sang case.