The principle of legality and international humanitarian law In the aftermath of World War II the international community, outraged by the In the aftermath of World War II the international community, outraged by the

atrocities committed, decided to update and improve the international standards for humanitarian treatment in war. This way, a series of agreements were reached in 1949 adopting or updating the four Geneva Conventions.⁸²⁷ Following the contemporary

823 UDHR, Art. 5; ICCPR, Art. 7; Geneva Convention (GC) I, Art. 12; GC II, Art. 12; GC III Arts. 13, 17 and 87; GC IV Arts. 27 and 32; UN General Assembly, Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment, 10 December 1984, Res.

39/46, 1465 UNTS 85, available at:

https://www.ohchr.org/en/professionalinterest/pages/cat.aspx; UN General Assembly, Convention on the Rights of the Child, 20 November 1989, UNTS vol. 1577, p. 3, Art. 37 (a), available at: https://www.ohchr.org/en/professionalinterest/pages/crc.aspx. Also see, among others the 1977 GC Additional Protocol I, Art. 75(2)(a)(ii); 1977 GC Additional Protocol II Art. 4(2)(a); ECHR, Art. 3; ACHR, Art. 5(2); ACHPR, Art.5.

824 UN General Assembly, Convention on the Non-Applicability of Statutory Limitations to War Crimes and Crimes Against Humanity, 26 November 1968, A/RES/2391(XXIII).

825 Convention on the Non-Applicability of Statutory Limitations to War Crimes and Crimes Against Humanity, Art. 1.

826 UN General Assembly, International Convention on the Suppression and Punishment of the Crime of Apartheid, 30 November 1973, A/RES/3068(XXVIII), Art. I. For further information on the codification process of international crimes, see with various further references M. Cherif Bassiouni, «Codification of International Criminal Law», Denver Journal of International Law and Policy 45, n.^o 3 (2017): 333-64; Boot, Nullum crimen sine lege and the subject matter jurisdiction of the International Criminal Court: genocide, crimes against humanity, war crimes, 401-608; Cassese, «Crimes Against Humanity»; Bassiouni, Crimes Against Humanity in International Criminal Law. Margalida Capellà, La tipificación internacional de los crímenes contra la humanidad, 359 (Valencia: Tirant lo Blanch, 2005).

827 ICRC, Geneva Convention for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field (First Geneva Convention), 12 August 1949, 75 UNTS 31; ICRC,

trend to internationally recognise the right of individuals against retroactive laws and punishments, the Third and the Fourth Geneva Conventions included provisions enshrining the principle of legality. Article 99 of the Third Geneva Convention relative to the Treatment of Prisoners of War established that

“No prisoner of war may be tried or sentenced for an act which is not forbidden by the law of the Detaining Power or by international law, in force at the time the said act was committed.(…)”⁸²⁸

The Fourth Geneva Convention relative to the Protection of Civilian Persons in Time of War included as well the protection against ex post facto laws and the prohibition of retroactive application of laws against a civilian population by an occupying power. Thus, Article 65 establishes:

“The penal provisions enacted by the Occupying Power shall not come into force before they have been published and (…) (t)he effect of these penal provisions shall not be retroactive.”⁸²⁹

Accordingly, Article 67 determines:

“The courts shall apply only those provisions of law which were applicable prior to the offence, and which are in accordance with general principles of law, in particular the principle that the penalty shall be proportionate to the offence (…).”⁸³⁰

Additional Protocols I and II to the Geneva Conventions, approved in 1977, relating to the protection of victims of international and non-international armed conflicts, also incorporate the non-retroactive rule. Article 75(4)(c) of Protocol I determines that:

“No one shall be accused or convicted of a criminal offence on account of any act or omission which did not constitute a criminal offence under the national or international law to which he was subject at the time when it was committed;

nor shall a heavier penalty be imposed than that which was applicable at the Geneva Convention for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea (Second Geneva Convention), 12 August 1949, 75 UNTS 85;

ICRC, Geneva Convention Relative to the Treatment of Prisoners of War (Third Geneva Convention), 12 August 1949, 75 UNTS 135; ICRC, Geneva Convention Relative to the Protection of Civilian Persons in Time of War (Fourth Geneva Convention), 12 August 1949, 75 UNTS 287.

828 Third Geneva Convention, Art. 99.

829 Fourth Geneva Convention, Art. 65.

830 Ibid., Art. 67.

time when the criminal offence was committed; if, after the commission of the offence, provision is made by law for the imposition of a lighter penalty, the offender shall benefit thereby.”⁸³¹

To better understand the scope and meaning of this provision it is relevant to examine the ICRC comments on this Article. First, the Committee recognised that the provision was directly inspired by ICCPR Article 15 and ECHR Article 7.⁸³² Then, the ICRC acknowledged that regarding criminal law, domestic courts firstly apply their own national legislation and that in some countries international law provisions could only be applied if they have been previously incorporated in the national legislation.

The Committee recalled that in numerous European States the punishment of international crimes has, since the Second World War, frequently encountered

“obstacles which could only be overcome by invoking the need to repress crimes rightly condemned by all nations, even in the absence of rules of application. This reference to international law has often been called the "Nuremberg clause".”⁸³³

The ICRC continued explaining that even though the principle of legality is fundamental in domestic criminal law “the lex should be understood in the international context as comprising not only written law, but also unwritten law, since international law is in part customary law”.⁸³⁴ The Committee concluded stating that governments should adopt the necessary legislation for the repression of international crimes, and in this way “they can avoid the criticism of acting arbitrarily by promulgating retroactive penal laws, even though international law may authorize them to do so.”⁸³⁵

831 GC Additional Protocol I, Art. 75(4)(c). Similarly, GC Additional Protocol II Art. 6 (c):

“No one shall be held guilty of any criminal offence on account of any act or omission which did not constitute a criminal offence, under the law, at the time when it was committed; nor shall a heavier penalty be imposed than that which was applicable at the time when the criminal offence was committed; if, after the commission of the offence, provision is made by law for the imposition of a lighter penalty, the offender shall benefit thereby.”

832 ICRC, Commentary on the Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I),

1987, Geneva, para. 3101, available at: https://ihl-

databases.icrc.org/applic/ihl/ihl.nsf/Comment.xsp?action=openDocument&documentId=E4634 0B132AC1B86C12563CD004367BF.

833 Ibid, para. 3103.

834 Ibid, para. 3104.

835 Ibid, para. 3105.

The nullum crimen provision of the Additional Protocols I and II are significantly more complete than those of the Third and Fourth Geneva Convention. In fact, Protocol I provision is almost identical to the one in the ICCPR, and except for the Nuremberg clause, it incorporates most of its elements, as the express reference to international law as a source of criminalization, nulla poena or lex mitior. Both Protocols clearly prohibit retroactive crime creation and retroactively increased penalties. And they required that the law grounding a criminal prosecution had to be applicable to the actor at the moment he committed the crime.

The inclusion of the non-retroactivity rule in the Additional Protocol II is of particular significance since it applies to internal armed conflicts. Generally, these situations represent a serious danger for the rule of law and fundamental principles as non-retroactivity could easily be ignored. However, 169 States have already adhered to the Protocol, and therefore, have accepted the international obligation to respect in their domestic legal systems the principle of non-retroactivity of crimes and punishments even in the extreme circumstances of a civil war. The widespread adoption of this Protocol is very strong evidence of the prominence of the nullum crimen, nulla poena rule in the international community.⁸³⁶ Moreover, the International Committee of the Red Cross has found that the prohibition of retroactive crimes and punishments has become “a norm of customary international law applicable in both international and non-international armed conflicts.”⁸³⁷

In conclusion, international humanitarian law enshrines a version of the legality principle that recognises international law as a valid source of criminalization. The non- retroactivity provisions do not require the previous law criminalising the conduct to be a written statute, and therefore customary international law is accepted as a valid legal ground for prosecutions.⁸³⁸ Similarly, States should in all circumstances respect the prohibition of retroactive crimes and punishments that is understood as a non- derogable obligation.

836 Olásolo, ‘El Principio Nullum Crimen Sine Iure En El Derecho Internacional Contemporáneo’, 24; Kenneth S. Gallant, The Principle of Legality in International and Comparative Criminal Law (Cambridge: Cambridge University Press, 2008), 208.

837 Federico Andreu Guzmán, Retroactividad Penal de Crímenes Internacionales, ed. Comisión Colombiana de Juristas (Bogotá, Colombia: Opciones Gráficas Editores Ltda., 2012), 39.

838 Kai Ambos, La Parte General Del Derecho Penal Internacional, trans. Ezequiel Malarino (Montivideo, Uruguay: Konrad-Adenauer-Stiftung e. V., 2005), 104. For further information on the principle of legality in the international humanitarian law system, see Gallant, The Principle of Legality in International and Comparative Criminal Law, 207–13.

CHAPTER 4: THE PRINCIPLE OF LEGALITY APPLIED BY MODERN