Two projects to create the international criminal courts were devised during the 20th century. On 1 July 2002, the Rome Statute of the International Criminal Court entered into force. On 16 November 1937, the Convention for the Creation of an International Criminal Court was opened for signature at Geneva. The latter never entered into force, an event made contingent on the coming into force of its companion Convention for the Prevention and Punishment of Terrorism, which also never occurred. The use to be made of law in each court forms the core of this discussion: the Rome Statute Court will rely on both vertical and horizontal approaches to the exercise of jurisdiction, and will utilise a harmonised approach to substantive criminal law; the 1937 court would have utilised domestic criminal law, in that the intent behind the 1937 convention was to make available an alternate forum, should the need arise. It is argued in particular that a horizontal approach to international criminal law may hold more seeds of future discord than a vertical approach, as harmonised law-making and enforcement lack a much-needed critical foundation. Crucially, the new International Criminal Court could greatly disturb the existing distribution of power and authority originally designed into the United Nations Charter, and effect a major shift in power politics, thus upsetting the balance between the principle of non-interference in state domestic affairs and the maintenance of international peace