Judgement in the high-profile extradition appeal of Rwanda v Vincent Brown & Ors is expected imminently. The Rwandan Government’s appeal is likely to be its final bid to secure the extradition of five alleged genocidaires to stand trial in Rwanda. If the appeal fails the men will remain in the UK—which raises the question, must the UK authorities investigate the allegations?

The recent Trial International Report shows that use of universal jurisdiction is on the rise. In 2016, 13 countries opened 47 cases based on the principle, including two for offences of genocide. Following our previous blog on universal jurisdiction and the refugee crisis, which set out the various ways in which the UK is able to exercise jurisdiction over certain extra-territorial offences, this post examines whether there is an obligation to do so, specifically over offences of genocide.

Obligations on states arise as a matter of public international law, the main sources of which are treaty law and custom. If we look to treaty law as a possible source of an obligation to exercise jurisdiction, the starting point is the Convention on the Prevention and Punishment of the Crime of Genocide 1948. Article 6 states that persons charged with genocide “shall be tried by a competent tribunal of the State in the territory of which the act was committed, or by such international penal tribunal as may have jurisdiction”. It doesn’t envisage states, such as the UK, trying perpetrators for acts committed outside their territory, much less require them to do so. The ICJ considered the issue in the case of Bosnia v Serbia, Judgment of 26 February 2007 and held that while Article 6 does not prohibit states from conferring jurisdiction on their courts in such circumstances, “it certainly does not oblige them to do so”.

Turning to customary law—these are the ‘unwritten rules’ of international law which develop over time. As a practice develops it may crystallise into a legally binding norm. Two elements are necessary for this to occur; first, states must act in a particular way (known as “state practice”) and second, they must do so because they believe they are under a legal obligation to do so (termed “opinio juris”). Though there is some controversy over this point, it is usually assumed that state practice must be representative, extensive and virtually uniform.

Can it be said that a rule of custom has developed which obliges states to prosecute perpetrators of genocide? Probably not. A survey of cases via the Trial Watch Project database shows that domestic prosecutions for genocide have only been brought in 16 states (out of a total of 195). Six states have refused extradition requests for offences of genocide without instituting domestic proceedings. Furthermore, Amnesty International has published a survey of domestic criminal legislation which shows that fewer than 50% of states permit prosecutions for genocide under universal jurisdiction principles. This evidence hardly seems to live up to the requirements of extensive and virtually uniform state practice.

Turning to opinio juris, the International Law Commission has, in the course of its work on the principle of aut dedere aut judicare, asked States whether they consider “the obligation to extradite or prosecute as an obligation under customary international law and if so to what extent”. Of the responses received, Belgium is the only state which claimed unambiguously that a customary obligation exists to prosecute or extradite for offences of genocide. Notably the UK replied that it applies the “extradite or prosecute” principles only to certain offences, including torture. Those offences do not include genocide.

At this point in time, there is probably no legal obligation on states to prosecute offences of genocide pursuant to universal jurisdiction. But, as the Trial International report demonstrates, practice in this area of law is rapidly developing. Another factor which may spur the development of the law is the war in Syria; because an international tribunal seems unlikely, domestic prosecutions offer the only real hope of combating impunity there. There may soon come a time when state practice supports the creation of a customary rule, at least within Europe.