Sources of International Criminal LawPaweł Aleksander Kupis
‘Crimes against international law are committed by men, not by abstract entities, and only by punishing individuals who commit such crimes can the provisions of international law be enforced’. This is probably the most renowned phrase from the judgement of the International Military Tribunal at Nuremberg. In more than six decades which have passed since the International Military Tribunal judgement was handed down, the recognition and the understanding of the concept of individual responsibility under international criminal law has been significantly reinforced and developed. Particularly, since the establishment of the International Criminal Tribunal for the former Yugoslavia, the International Criminal Tribunal for Rwanda, the International Criminal Court as well as other hybrid courts or internationalised domestic courts and tribunals such as the Special Court for Sierra Leone, the Extraordinary Chambers of Cambodia, Kosovo Regulation 64 panels, East Timor Special Panels for Serious Crimes, the Bosnia War Crimes Chamber, the Special Tribunal for Lebanon, the Iraqi High Tribunal and the Serbian War Crimes Chamber. The concept of individual responsibility under international criminal law has a much higher profile today, than ever before in the history. The rules of international law concerning international crimes and individual responsibility have not always appeared sufficiently clear.
Unlike national law, international law is not the ‘product of statute for the simple reason that there is yet no world authority empowered to enact statutes of universal application. International law is the product of treaties, conventions judicial decisions and customs which have received international acceptance or acquiescence’. Because of the anarchic nature of world politics, the formation of international law is more complicated than that of domestic law. The traditional starting point for an enquiry of the sources of international law is Art. 38 of the statute of the International Court of Justice. Article 38 provides that:
(1) The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shall apply:
(a) international conventions, whether general or particular, establishing rules expressly recognised by the contesting States;
(b) international custom, as evidence of a general practice accepted as law;
(c) the general principles of law recognized by civilized nations;
(d) subject to the provisions of Article 59, judicial decisions and the teachingsof the most highly qualified publicists of the various nations, as subsidiary meansfor the determination of rules of law.
Article 38(1) does not, of course, exhaust the list of the sources of international law. Although the Article 38 is only limited to the sources of international law which the International Court of Justice must apply, it is generally accepted by the international community that this Article identifies the general sources of international law. There is no indication of any priority or hierarchy of the sources listed in Art. 38, except for the single reference to subsidiary means in item (d).
International treaties and international custom are the most important sources of public international law, and thus international criminal law. Conventions or treaties are more modern and more deliberate method of creating law because they represent an agreement reached between states in accordance with the principle of “pacta sunt servanda”. According to the Vienna Convention on the Law of Treaties, ‘every treaty in force is binding upon the parties to it and must be performed by them in good faith’. Examples of the treaties which are relevant in terms of international criminal law are the Hague Conventions of 1907, the four Geneva Conventions of 1949 with the Additional Protocols I and II of 1977and the Convention on the Prevention and Punishment of the Crime of Genocide of 1948.The Rome Statute of the International Criminal Court is also a multilateral treaty. Boththe Statute of the International Criminal Tribunal for Rwanda and the Statuteof the International Criminal Tribunal for the former Yugoslavia were adopted pursuantto Chapter VII United Nations Security Council resolutions and are binding on all United Nations member states.
Custom is the oldest source of international law. The existence of customary rules has evolved from the state practice which gives rise to a legitimate expectation of similar behaviour in the future. Obviously, there are certain conditions which must be fulfilled before practice becomes a binding international law. These conditions derive mainly from the decisions, rulings and advisory opinions, of the International Court of Justice and its predecessor, the Permanent Court of Justice. It is not a requirement that each and every state conforms to a certain practice in order for a universal norm of a customary law to develop. The practice must be fairly general. Customary international law is binding on both existingand new States. The development of those rules is usually a time consuming process because it takes a considering amount of time for the practice to be established. The reportof the United Nations Secretary-General on the International Criminal Tribunal for the former Yugoslavia Statute gives some support to the rules of customary law relevant to international criminal law:
’ 34. (...) the international tribunal should apply rules of international humanitarian law which are beyond any doubt part of customary law so that the problem of adherence of somebut not all States to specific conventions does not arise. This would appear to be particularly important in the context of an international tribunal persecuting persons responsiblefor serious violations of international humanitarian law‘.
The principle of individual criminal responsibility under international law was recognised in the Charter and then in the Judgement of the Nuremberg Military Tribunal.The International Law Commission, at the request of the United Nations General Assembly, prepared a formulation of the principles of international law recognised by the Charterand the Judgement of the Nuremberg Tribunal.
 International Military Tribunal. Judgement: The Law of the Charter, available at http://avalon.law.yale.edu/imt/judlawch.asp, 14.01.2012.
 Vide: e.g. W. Schabas, The UN International Criminal Tribunals: The Former Yugoslavia, Rwanda and Sierra Leone, Cambridge, 2006., R. Kerr, The International Criminal Tribunal for Former Yugoslavia: An Exercise in Law, Politics and Diplomacy, Oxford, 2004.
 Vide: e.g. V. Morris, M.P. Scharf, The International Criminal Tribunal for Rwanda, New York, 1998., L.J. van den Herik, The Contribution of the Rwanda Tribunal to the Development of International Law, The Hague, 2005.
 W. Schabas, International Criminal Court in: D. McGoldrick, P. Rowe, E. Donelly (eds.), The Permanent International Criminal Court: Legal and Policy Issues. Oxford, 2004.
 Vide: e.g. C.P.R. Romano, A.Nollkaemper, J.K.Kleffner, Internationalized Criminal Courts, Oxford, 2004., Cryer et al., Introduction to International Criminal Law., L.A. Dickson, The Promise of Hybrid Courts, 97 AJIL, 2003, p.295., The UN International Criminal Tribunals.
 United States of America v. Josef Altstoetter et al, Trials of War Criminals Before the Nuremberg Military Tribunals Under Control Council Law No. 10, Vol. III, pp. 974–975.
 M. Dixon, Textbook on International Law, New York, 2007, p.23.
 M.N. Shaw, International Law, 2008, pp.70 – 71.
 J. Thormundsson , The Sources of International Criminal Law with Reference to the Human Rights Principles of Domestic Criminal Law, available at http://www.scandinavianlaw.se/pdf/39-17.pdf, 14.01.2012
 Vienna Convention on the Law of Treaties 1969, Article 26, available at http://untreaty.un.org/ilc/texts/instruments/english/conventions/1_1_1969.pdf, 14.01.2012
 Vide: United Nations Security Council Resolutions S/RES/1512 (2003) and S/RES/827 (1993)
 M.Dixon, op cit, pp. .31-34.
 Vide: Military and Paramilitary Activities in and against Nicaragua, 1986, I.C.J. 14., United Kingdom v. Norway, 1951 I.C.J. 116
 Report of the Secretary-General Pursuan to Paragraph 2 of Security Council Resolution 808 (1993), available at http://www.icty.org/x/file/Legal%20Library/Statute/statute_re808_1993_en.pdf, 12.01.2012
 Charter of the International Military Tribunal, Article 6.:‘The Tribunal shall have the power to try and punish persons who (...) as individuals or as members of organisations, committed any of the following crimes. The following acts [crimes against peace, war crimes and crimes against humanity] are crimes coming within the jursidition of the Tribunal for which there shall be individual responsibility., Available at http://avalon.law.yale.edu/imt/imtconst.asp, 14.01.2012.
 R. Gallmetzer, M. Klamberg, Individual responsibility for crimes under international law; The UN ad hoc Tribunals and the International Criminal Court. The Summer School on International Criminal Law, 2005, available at http://ssrn.com/abstract=1576024, 14.01.2012.