Les crimes contre l'humanité et les principes de la légalité: à quoi le contrevenant pourrait-il s'attendre?

Les juges ne sont que la bouche qui prononce les paroles de la loi, des êtres inanimés qui ne peuvent ni en adresser la force ni la rigueur. "
Charles de Secondat Montesquieu, L'esprit des Lois, Livre XI, Ch. III, 127 (1748).
" If the interpretation of laws is an evil, their obscurity, which necessarily entails interpretation, is obvioulsy another evil (...). "
Cesare Beccaria, On crimes and Punishment, 10-12 (D. Young trans. 1986).
For Charles de Montesquieu, judges were only those through whose mouth the law spoke, and they could neither address the law's force or rigor. However if the law is unclear, judges necessarily have to address such considerations, and give their interpretation of its obscure parts. The fundamental "principles of legality" emerged from such social contract theorists, and since then constantly developed. They are enshrined in the maxims nullum crimen sine lege, nulla poena sine lege, and also contain another fundamental principle of criminal law: the prohibition of ex post facto criminal laws and its derivative rule of non-retroactive application of criminal laws and criminal sanctions. A corollary is the requirement of specificity and the prohibition of ambiguity in criminal legislation.
Before Nuremberg and Tokyo, the question of legality only arose once in the entire history of the Permanent Court of International Justice (hereafter PCIJ), in the Advisory Opinion on the Consistency of Certain Danzig Legislative Decrees with the Constitution of the Free City, December 4, 1935 :
"Instead of applying a penal law equally clear to both the Judge and the party accused, (...) there is a possibility under the new decrees that a man find himself placed on trial and punished for an act which the law did not enable him to know was an offence, because its criminality depends entirely on the appreciation of the situation by the Public Prosecutor and by the Judge."
As far as crimes against humanity are concerned the issue of legality arose for the first time from the desire to investigate, try and punish those responsible for the atrocities committed on Axis territory against nationals of non-Allied countries. On 8 August 1945, the four Allied Powers (France, Great Britain, the USSR and the United States) concluded the London Agreement. Annexed to it was the Charter of the International Military Tribunal for the Prosecution and Punishment of the Major War Criminals of the European Axis, article 6 of which provided that the Tribunal had the power "to try and punish persons who, acting in the interests of the European Axis countries, whether as individuals or as members of organisations" committed crimes against peace, war crimes, or crimes against humanity.
The latter category was defined as follow:
c) crimes against humanity: namely, murder, extermination, enslavement, deportation or other inhumane acts committed against any civilian population, before or during the war; or persecutions on political, racial, or religious grounds in execution of or in connection with any crime within the jurisdiction of the Tribunal, whether or not in violation of the domestic law of the country where perpetrated."
Since the crimes were incorporated for the first time in an international instrument, they could have been seen as ex post facto law, and be regarded as violating the principles of legality. In addressing this defence claim the Nuremberg Tribunal concluded: "The Charter is not an arbitrary exercise of power on the part of the victorious nations, but in the view of the Tribunal (...) is the expression of international law existing at the time of its creation; and to that extent is itself a contribution to international law."
It is true that the term "crimes against humanity" existed prior to World War II. The 1868 Saint Petersburg Declaration limited the use in times of war of certain explosive or incendiary projectiles, since they were declared contrary to the laws of humanity. In 1907, the well-known Martens clause provided as follows: "until a more complete code of the laws of war has been issued, () the inhabitants and the belligerents remain under the protection and the rule of the principles of the law of nations, as they result from the usages among civilized peoples, from the laws of humanity, and the dictates of the public conscience." In 1915 the expression "crimes against humanity" was used for the first time as such in the 1915 Declaration by the governments of France, Great Britain and Russia denouncing the massacre of Armenians taking place in Turkey: "crimes against humanity and civilisation for which the members of the Turkish Government will be held responsible together with the agents implicated in the massacres." Also in the 1919 Report of the Commission on the Responsibilities of the Authors of War and on Enforcement of Penalties for Violations of the Laws and Customs of War the majority of the members concluded that the German Empire and its Allies carried out the war "by barbarous or illegitimate methods in violation of the established laws and customs of war and the elementary laws of humanity" and "all persons belonging to enemy countries (...) who have been guilty of offences against the laws and customs of war or the laws of humanity are liable for criminal prosecution."
But whether this was a legislative act creating a new crime or whether it reflected customary international law still remains controversial.
Legislative act or not, the definition given in the Charter of the International Military Tribunal has been challenged, especially concerning the nexus to war. Although it has recently been asserted that "the post-Nuremberg developments have failed decisively to resolve the nexus issue," there should be no doubt that the concept of crimes against humanity under customary international law applies to atrocities committed during peacetime. The nexus to war was not included in the definition of crimes against humanity contained in Control Council Law No. 10. Second, in its report on the development of the laws of war at the conclusion of the Nuremberg and Control Council Law No. 10 trials, the United Nations War crimes Commission concluded that international law may now sanction individuals for crimes against humanity committed not only during war but also during peace. Third, in the International Law Commission's formulation of the Principles of International Law Recognized in the Charter of the Nuremberg Tribunal and in the Judgment of the Tribunal, the International Law Commission indicated that crimes against humanity of the inhuman act type could be committed apart from war. Fourth, article 1 of the 1968 Convention on the Non-Applicability of Statutory Limitations to War crimes and crimes Against Humanity provides that such limitations do not apply to "[c]rimes against humanity whether committed in time of war or in time of peace."
Since the International Military Tribunal, definitions have been as diverse as numerous. At least some particular crimes against humanity such as genocide, apartheid and enforced disappearances have been clearly identified. The next developments have been the adoption by the Security Council of the International Criminal Tribunal for the former Yugoslavia (hereafter ICTY) and the International Criminal Tribunal for Rwanda (hereafter ICTR) statutes , and more recently the International Criminal Court (hereafter ICC) statute.
One may hope the ICC statute will have an authoritative status, being the product of national positions as to the content of customary law. Consequently the present analysis will focus on the definition given in its article 7 concerning crimes against humanity. It will try to give the potential offender some guidelines regarding the definition of the crimes. In the end he may hopefully know what to expect at the threshold of the new millennium, if ever prosecuted.