Jurisdiction in criminal law in the UK is generally limited to acts occurring within the UK though there are some limited exceptions, the main ones being homicide, bribery, certain sexual offences involving children, and some fraud and terrorism offences.

In addition to these specific offences however, there is a small class of offences, which have, over the years since the Second World War, been the subject of various international conventions and treaties. The list of such offences has grown over this period but they can broadly be described as war crimes and related offences.

The result of these treaties and their implementation within domestic UK legislation has been the development of the principle of Universal Jurisdiction in respect of these offences - the ability to prosecute an individual for an offence in this jurisdiction for an offence wholly occurring in another jurisdiction and having no connection whatsoever to the UK. This lack of a requirement of any nexus to the UK marks these limited offences out from those specific offences listed above in relation to which, while they may have occurred overseas, there is invariably an underlying rationale that relates to British citizens or interests.

Alongside these developments in domestic criminal law, since the creation of the International Criminal Tribunal for the former Yugoslavia (ICTY) in 1993, these offences have increasingly been dealt with before international tribunals. The creation of the International Criminal Court (ICC) in 2002 represented the realisation of a longstanding international ambition to establish a permanent institution before which such offences can be prosecuted. The recognition of the concept of Universal Jurisdiction is essential for the operation of the ICC which sits outside any national jurisdiction. Though the operation of these tribunals is wholly independent of the UK, their work can have relevance in the UK; the recent referral of a complaint to the ICC in respect of the actions of British forces in Iraq is a good example of this.

Proceedings for war crimes and other offences of Universal Jurisdiction are rare in the UK. That said, there is some evidence of increased activity by both police and NGOs in respect of investigations relevant to this area of work. When these cases do arise they create unique legal and practical challenges for those involved in prosecuting and defending and for the courts. As well as the normal considerations that arise in the preparation of a serious criminal case, there are a range of additional issues that are not usually encountered in criminal cases in the UK. In the determination of these issues the courts must often look beyond the usual criminal law jurisprudence of the English courts, both because of its limited relevance to such cases, and because issues of Public International Law are invariably engaged.