Norma relacionada
Colombia
Practice Relating to Rule 101. The Principle of Legality
Colombia’s Instructors’ Manual (1999) provides: “Nobody can be tried except according to the laws that pre-existed the alleged act.” 
Colombia, Derechos Humanos & Derecho Internacional Humanitario – Manual de Instrucción de la Guía de Conducta para el Soldado e Infante de Marina, Ministerio de Defensa Nacional, Oficina de Derechos Humanos, Fuerzas Militares de Colombia, Santafé de Bogotá, 1999, p. 10.
Colombia’s Law on the Disciplinary Regime of the Armed Forces (2003) states: “The addressees of the present rules may only be investigated and disciplinarily sanctioned for acts which constituted an offence according to the law in force at the time when the acts took place.” 
Colombia, Law on the Disciplinary Regime of the Armed Forces, 2003, Article 3.
Colombia’s Criminal Procedure Code (2004) states: “Nobody may be subjected to an investigation or convicted except in accordance with the procedural law in force at the time of the acts”. 
Colombia, Criminal Procedure Code, 2004, Article 6.
In 2007, in the Constitutional Case No. C-291/07, the Plenary Chamber of Colombia’s Constitutional Court stated:
Taking into account … the development of customary international humanitarian law applicable in internal armed conflicts, the Constitutional Court notes that the fundamental guarantees stemming from the principle of humanity, some of which have attained ius cogens status, … [include] the obligation to respect … the principle of legality regarding crimes and penalties. 
Colombia, Constitutional Court, Constitutional Case No. C-291/07, Judgment, 25 April 2007, p. 112.
[footnote in original omitted]
In 2009, in the Constitutional Case No. C-801/09, the Plenary Chamber of Colombia’s Constitutional Court was called upon to decide on the constitutionality of the 2002 ICC Elements of Crimes, the 2002 ICC Rules of Procedure and Evidence and the corresponding domestic law approving them. Regarding the compatibility of these instruments with the principle of legality, the Court stated:
[I]n the … Case No. C-578 of 2002, the [Constitutional] Court identified the provisions of the [1998] Rome Statute of the International Criminal Court that contain different treatment to that provided for in the [1991] Political Constitution, recognizing that, in any case, these were expressly authorized by Legislative Act No. 2 of 2001, as long as it is understood that their effects are limited exclusively within the scope of the said Statute.
2.2.18 … The Court highlighted that even though articles 22 and 23 of the Rome Statute establish the principle of legality and the prohibition of analogy as fundamental principles for the prosecution of international crimes, … articles 6, 7 and 8 are imprecise in the description of [penalized] conduct. This would suggest that such provisions are subject to a different standard from the principle of legality that guides domestic criminal law. However, the Court explained that this difference was possible because … it was accepted by international law and expressly authorized by Legislative Act No. 2 of 2001 …
5.3.11. This Court has stated that, in accordance with the principle of legality, the punishable conduct, the penalties themselves, the criteria for their determination and the procedures for their imposition must have been defined in advance, by law and in a sufficiently clear manner, so that the people to whom they are addressed know with certainty when they should answer for the conduct prohibited by law. The Rome Statute and the complementary instrument containing the [2002 ICC] Rules of Procedure and Evidence and the [2002 ICC] Elements of Crimes are in line with this principle, as they regulate in a clear, systematic and harmonious manner all the aspects related to the offences within the jurisdiction of the International Criminal Court, as well as their investigation, prosecution and punishment. 
Colombia, Constitutional Court, Constitutional Case No. C-801/09, Judgment, 10 November 2009, §§ 2.2.13, 2.2.18 and 5.3.11.
[emphasis in original]
In 2010, in the Plazas Vega case, Colombia’s Third Criminal Court of the Specialized Circuit of Bogotá stated:
From its earliest conception until today, the principle of legality has been conceived as including three essential premises, namely: (i) only a penalty established in law prior to the facts can be imposed (nulla poena sine lege), (ii) for someone to be convicted, his or her conduct must have been previously defined as a crime (nulla poena sine crimine) and (iii) a legal penalty must be attributed to the violation (nullum crimen sine poena legale). In view of the above, the [1998] Rome Statute of the International Criminal Court established the following requirements: a person may only be punished for an act which (a) was provided for at the time it was committed (lex scripta), (b) [according to a law that was] in force at the time it was committed (lex praevia), (c) defined in a sufficiently clear manner (lex certa), (d) was not expanded through analogy (lex stricta) and (e) was attributed a penalty by the relevant rule (nulla poena).
All this is supported by article 29 of the [1991] Constitution… , which states: “no one may be tried except in conformity with the laws that predate the act of which the person is accused, before a competent court or tribunal and in accordance with the procedure appropriate to each case”.
In the same vein, article 6 of Law 599 of 2000 [Penal Code] provides for this judicial guarantee in the following terms:
Legality. No one may be tried except in conformity with the laws that predate the act of which the person is accused, before a competent court or tribunal and in accordance with the procedure appropriate to each case …
The permissible or favourable law, even when subsequent, shall, without exception, be applied rather than the restrictive of unfavourable [law]. It also applies to convicted persons.
Analogy shall only be applied to permissive matters. 
Colombia, Third Criminal Court of the Specialized Circuit of Bogotá, Plazas Vega case, Judgment, 9 June 2010, pp. 95–96.
[footnotes in original omitted]
Regarding the application of the principle of legality to the crime of enforced disappearance, in view of the permanent nature of this crime, the Court held:
[I]f the crime is of an instantaneous nature, the applicable law will be the one in force before the commission of the punishable act. However, in view of the permanent nature of the crime of enforced disappearance, … it is possible to apply the law [in force] during the unlawful situation, which was willingly maintained by the defendant …
In the same vein, the Inter-American Court of Human Rights … [stated]:
… The Court observes that the crime of enforced disappearance has been in force in the Mexican legal system since the year 2001 … , that is, prior to the presentation of the preliminary inquiry before the District Judge on duty in August 2005 … In that sense, the Court reiterates, as it has done in other cases, that since this is a crime of permanent execution, with the entry into force of the legal definition of the crime of enforced disappearance of persons in the State, the new law is applicable since the criminal behavior is still in execution, without this representing a retroactive application.
Moreover, … [the situation where] a permanent offence for which, during the period of its execution, several laws entered into force in succession, the last one of which was less favourable to the defendant because, for instance, of providing for a higher penalty, [is different from the situation where] the criminal conduct … continues to be executed and later on receives a different legal classification … as was the case for the crimes of aggravated kidnapping and aggravated enforced disappearance. In the first case, according to constitutional law and the case law of the higher courts, the most favourable law must be applied. In the second case, on the other hand, the principle of favourability is not a criterion for determining the legal classification to be applied to a specific case. In this situation, the principles regarding the apparent concurrence of laws shall be applied. 
Colombia, Third Criminal Court of the Specialized Circuit of Bogotá, Plazas Vega case, Judgment, 9 June 2010, pp. 96–98 and 100–101.
[footnotes in original omitted]
Regarding the application of the principle of legality to the crime of enforced disappearance in view of the provision for this crime under international law, the Court found:
[T]the crime [of enforced disappearance] is a crime against humanity. Although it was not provided for in criminal law before the entry into force of Law No. 589 of 2000, nor before the approval of the [1994] Inter-American Convention on the Forced Disappearance of Persons, one must consider that, at the time of the facts, there were already international instruments that protected the rights that are nowadays protected by the provision on the crime [of enforced disappearance] and that, since ancient times, have constituted rules of ius cogens or customary law, which were recognized in the Constitution of 1866 and which must be complied with by the State. In this sense, the Criminal Chamber of the Supreme Court of Justice, when called upon to decide on the crime against humanity of genocide, which, at the time of the facts, … was not incorporated into the criminal legislation and whose conduct was included in the general crime of aggravated homicide, stated:
… [A]lthough it is certain that the principle of legality requires a crime to be legally provided for before someone can be convicted of it, it is also certain that the domestic legislation must comply with the content of international treaties … This is why … the content of these instruments can be applied as a source of law in view of the delay of the legislator in adapting the laws accordingly. Therefore, it would be possible to apply, without violating the principle of legality, the content of an international treaty recognized by Colombia that criminalizes and imposes a punishment for a certain crime, regardless of the lack of a domestic law in this sense. 
Colombia, Third Criminal Court of the Specialized Circuit of Bogotá, Plazas Vega case, Judgment, 9 June 2010, pp. 98–100.
[footnotes in original omitted]
The Court further stated:
The present investigation originated on 6 and 7 November 1985, when the … self-styled “Iván Marino Ospina” branch of the guerrilla movement calling itself “M-19 – 19 April Movement” violently occupied the Palace of Justice in the centre of Bogotá, in an “operation” paradoxically named “Antonio Nariño for human rights”, with the aim of subjecting the then President of the Republic … to a political trial in light of the government’s alleged non-compliance with the peace agreements signed with the rebel group.
Moments after the start of the seizure [of the building], the Chief of Staff of the Thirteenth Brigade … activated the National Defence Plan “Tricolor 83” and the Brigade Operations Centre.
A tactical and intelligence operation was then carried out, directed and coordinated by the National Army and aimed at retaking the Palace of Justice and freeing the hostages …
… [T]he freed hostages were identified, questioned, listed and classified as follows: personnel not involved in the subversive operation; participants in the assault; and possible M-19 collaborators from inside the Palace of Justice …
In this way, members of the armed forces rescued from the Palace of Justice more than 200 people who, … in accordance with the recovery and rescue plan, were almost all moved to the Casa Museo del Florero and, after being identified, were released. However, 11 of the rescued persons have never been traced.
[I]t must be said that … at the time the events took place, the “secret” “special intelligence operations plan No. 002/80” was in full force. This plan was designed to “simultaneously identify, locate, capture and question M-19 members operating in the area under the jurisdiction of the BIM [Brigade XIII, of which the accused was a Colonel]” and assigned military targets belonging to this illegal armed group to the Cavalry School.
In view of the reprehensible actions of the members of the M-19 subversive group, who placed in danger the lives of the civilians who were inside the Palace, the Court cannot ignore the fact that the intervention of the public forces was imperative to re-establish the constitutional order that had been shattered. Likewise, it was legitimate for the military to work towards identifying and sorting the people who were evacuated from the conflict zone, and it was appropriate to use the Casa del Museo del 20 Julio as a command post for this work, in accordance with the operational manuals in force at the time. What, however, is inconceivable in a Social and Democratic State governed by the rule of law is that the authorities responsible for the security of their fellow citizens, for the maintenance of peaceful coexistence and fairness, act surreptitiously with total disregard for domestic and international norms related to the protection of human rights. 
Colombia, Third Criminal Court of the Specialized Circuit of Bogotá, Plazas Vega case, Judgment, 9 June 2010, pp. 1, 3, 5, 128 and 285–286.
[footnotes in original omitted]
In 2010, in the Diego Vecino and Juancho Dique case, the Justice and Peace Chamber of Colombia’s High District Court of Bogotá convicted two members of the paramilitary group Autodefensas Unidas de Colombia (United Self-Defence Forces of Colombia) of several crimes committed against the civilian population. The Court stated:
V.2.2. Deportation, expulsion, transfer or forced displacement of the civilian population
72. In the proceedings … it was mentioned that “considering the date of the facts, 10 March 2000, the legislation in force was the Decree-Law No. 100 of 1980, which did not provide for this conduct. However, considering that forced displacement is an offence of a permanent nature, its consummation ended when those responsible for this crime were demobilized because, by that date (July 2005), inhabitants of Mampuján had not yet returned.” Therefore, the applicable legislation is article 159 of Law 599 of 2000 [Penal Code].
V.2.3. Aggravated murder
79. It is clear that, while the legislation in force at the time when the massacre took place was the Decree-Law No. 100 of 1980, modified by Law No. 40 of 1993, in application of the principle of the most favourable legislation, the applicable legislation will be Law 599 of 2000, articles 103 and 104.
144. In summary, these demobilized individuals are convicted of grave breaches of international humanitarian law because, as participants in an armed conflict, they attacked the civilian population by displacing it from its territory, taking the lives of non-combatants and pillaging its property after the incursion. However, owing to the limitation imposed by the principle of legality and considering the date when the acts took place, the offences are considered to be ordinary crimes. 
Colombia, High District Court of Bogotá, Diego Vecino and Juancho Dique case, Judgment, 29 June 2010, §§ 72, 79 and 144.
[footnotes in original omitted]
In 2010, in the Constitutional Case No. C-936/10, Colombia’s Constitutional Court stated:
While the principle of discretionary prosecution involves the possibility of suspending, interrupting or even waiving prosecution, these possibilities are subjected to the principle of legality …
… [T]he Court emphasizes that the principle of legality informs the entire Colombian criminal legal system. It is a guarantee for citizens to have equal access to the administration of justice, under conditions of legal certainty and with confidence that the prosecution of crimes is preceded by clear rules that ensure that the administration of criminal justice will not be dependent on the goodwill of the authorities tasked with its execution.
In its strict sense, the principle of legality is known as the principle of specificity and requires penal provisions to be defined in law in a clear or specific way, so that the task of judicial officials (judges or prosecutors) is limited to determining whether a conduct or situation fulfils the requirements clearly described by the legislative body.
66. The principle of discretionary prosecution is conceived as an exception to the principle of legality and mandatory prosecution … [T]he conditions for its application must be fully defined and delimited by law. Vague and ambiguous rules regarding its functioning may lead to an extension of this principle to hypotheses that were not envisaged by the legislative body and may make decisions on suspension, interruption or waiver of prosecution more difficult. 
Colombia, Constitutional Court, Constitutional Case No. C-936/10, Judgment, 23 November 2010, pp. 50 and 92.
Regarding the context in which the amendment was made, the Court stated:
In recent years, the Colombian State has adopted various laws aimed at overcoming the situation of internal armed conflict in the country. Hence, while it is clear that the conflict has not fully ceased, it is also clear that all those measures have been aimed at disarming and reintegrating into society members of illegal armed groups. In other words, they have been aimed at achieving peace, without, however, admitting that the victims’ rights to truth, justice and full reparation can be disregarded. 
Colombia, Constitutional Court, Constitutional Case No. C-936/10, Judgment, 23 November 2010, p. 167.
In 2010, in the El Iguano case, the Justice and Peace Chamber of Colombia’s High District Court of Bogotá convicted a member of the paramilitary group Autodefensas Unidas de Colombia (United Self-Defence Forces of Colombia) of several crimes committed against the civilian population. The Court stated:
197. … [I]t is possible to conclude that the murders, torture, acts of terrorism, forced displacement, destruction of protected objects and extortions or arbitrary contributions attributed to the accused have a functional link with the internal armed conflict and, therefore, must be classified as war crimes regardless of the date when they were executed …
198. The facts … that took place before 25 July 2001 – when domestic legislation did not yet provide for crimes violating international humanitarian law – must also be classified as war crimes, in accordance with the guidelines of the Supreme Court of Justice in a recent decision. This does not violate the principle of legality because the 1949 Geneva Conventions entered into force for Colombia on 8 May 1962 by virtue of Law No. 5 of 1960, and the 1977 Additional Protocols, in particular Additional Protocol II of 8 June 1977, entered into force for Colombia on 15 February 1996 by virtue of Law No. 171 of 1994. Consequently, the State has the obligation to prevent and combat violations of international humanitarian law that have occurred since these dates, because:
it is acceptable to argue that the content of these instruments is applicable, as a source of law, in view of the delay of the legislative body in adapting the laws to what was defined therein. Therefore, it would be possible to apply, without violating the principle of legality, the content of an international treaty recognized by Colombia with regard to a crime prohibited and punished therein, even if there is no prior domestic law in this regard.
199. Pursuant to article 214 of the [1991] National Constitution, [these conventions] are part of the so-called “constitutional block” and, therefore, prevail in the domestic order and cannot be limited in a state of exception. This gives rise to the obligation of the Colombian State to “adapt its hierarchically inferior rules of the domestic legal order to the content of international humanitarian law, with the aim of fostering the material fulfilment of these values”. However, if the State does not comply with its duty to criminalize and punish acts that violate international humanitarian law, this does not imply that these acts will remain unpunished. Impunity should not be understood only as an absence of investigation and punishment, but also as having an investigation and punishment that do not correspond to the gravity of the crime committed, diminishing its importance at the national and international levels.
200. Therefore, the facts [at stake] … should be classified as war crimes despite the date of their execution being prior to 25 July 2001.
201. That being said, in respect of the constitutional principle of legality of crimes and penalties, in the moment when the criminal penalty will be assessed, the accused will be convicted of the crime of aggravated murder pursuant to articles 103 and 104 of the [2000] Penal Code.
202. The remaining facts – murders, acts of terrorism, forced displacements, destruction of protected objects and extortions or arbitrary contributions – , … committed before the entry into force of part II of the special part of our Penal Code (Law 599 of 2000), shall be punished as grave breaches of international humanitarian law pursuant to the specific criminal offences. 
Colombia, High District Court of Bogotá, El Iguano case, Judgment, 2 December 2010, §§ 197–202.
[footnotes in original omitted]
Regarding the classification and punishment of the offences committed by the group as crimes against humanity in view of the principle of legality, the Court stated:
247. Although the [1998] Rome Statute entered into force on 1 November 2002 by virtue of Law No. 742 of that same year, the Colombian State has not included a special title [in the Colombian Penal Code] regarding crimes against humanity. However, certain facts constitutive of these grave violations are criminalized.
248. In view of the above, there is a problem: although, in application of the “constitutional block”, it is possible to classify certain offences as crimes against humanity pursuant to the Rome Statute from the date of its entry into force for Colombia, how to classify those acts committed before those dates, as it cannot be retroactively applied?
249. The Inter-American Court of Human Rights has provided in its case law the doctrine in relation to crimes against humanity and their characteristics. The Court affirmed that the prohibition of these crimes has the character of jus cogens, which imposes on States the obligation to prosecute those responsible and not to grant them amnesty.
262. Likewise, the European Court of Human Rights [ECtHR] decided on the application of crimes against humanity by State domestic courts. In Kolk and Kislyiy v. Estonia, the domestic courts of Estonia had convicted the appellants of crimes against humanity committed in 1979. The ECtHR found that these convictions did not violate the [1950] European Convention on Human Rights because, characteriziing the crimes as crimes agains humanity, the relevant criminal conducts are not subject to statutes of limitation, regardless of whether on the date of the commission of these acts crimes against humanity were or not part of Estonian domestic law.
263. In its decision of 17 January 2006 in the Kolk and Kislyiy v. Estonia case, the ECtHR reaffirmed a well-known principle of international law regarding these serious crimes, stating:
266. The Court notes that even if the acts committed by the applicants could have been regarded as lawful under the Soviet law at the material time, they were nevertheless found by the Estonian courts to constitute crimes against humanity under international law at the time of their commission. The Court sees no reason to come to a different conclusion. It is noteworthy in this context that the Soviet Union was a party to the London Agreement of 8 August 1945 by which the Nuremberg Charter was enacted. Moreover, on 11 December 1946 the United Nations General Assembly affirmed the principles of international law recognized by the Charter. As the Soviet Union was a member State of the United Nations, it cannot be claimed that these principles were unknown to the Soviet authorities. The Court thus considers groundless the applicants’ allegations that their acts had not constituted crimes against humanity at the time of their commission and that they could not reasonably have been expected to be aware of that.
268. In application of the concepts presented by the Inter-American Court of Human Rights, the European Court of Human Rights and the International Criminal Tribunal for the former Yugoslavia to the Colombian case, it is clear that, based on the general principles of international law and the rules of jus cogens, a conduct can be classified as a crime against humanity although not criminalized as such at the domestic level. 
Colombia, High District Court of Bogotá, El Iguano case, Judgment, 2 December 2010, §§ 247–249, 262–263, 266 and 268.
[footnotes in original omitted]
In 2010, in the Juancho Dique case, the Criminal Appellate Chamber of Colombia’s Supreme Court of Justice stated:
Two legal questions are raised by the appeal that is now being decided: … the second is related to the validity of laws over time, and in particular whether it is possible that rules provided for in Title II of Book II of the [2000] Penal Code, entitled “Offences against Persons and Objects Protected by International Humanitarian Law”, which entered into force on 25 July 2001, are applicable in the punishment of conduct undertaken before that date.
1. The Chamber starts by asserting the principle of legality, recognized in our [1991] Political Constitution as a bastion of protection against arbitrariness. The recognition of this principle originates in the claims of the eighteenth-century European bourgeoisie, which was concerned about the imprecise content of what was prohibited … and thus imposing the arbitrariness of the sovereign …
Thus, legality limited the arbitrariness of the sovereign and modified the relation between men, power and the law, transforming subjects into citizens.
Under the principle of legality, the criminal law of the liberal State was born, understood as the scenario protecting the accused against an extremely broad discretionary capacity of the sovereign …
2. However, the principle of legality, as conceived by the French revolutionary, supposed the existence of the national State with three public powers working together harmoniously and sincerely committed to the development of the people they represented and protected, judicial guarantees being, above all, a barrier to the arbitrary power of the sovereign. This situation began to change in the middle of the twentieth century.
This was because, in the aftermath of the Second World War, the community, horrified by the military confrontation, the barbarity and intolerance that went beyond national borders and capacities, started to build a new criminal law with an international dimension, limited to four categories of crimes that offended humanity as a whole: the crime of aggression, genocide, crimes against humanity and grave breaches of international humanitarian law.
The civilized community reacted to these so-called “international crimes” because the rights violated concerned the whole of humanity. This gave rise to a new field of law within the international framework, which had some categories significantly different from those of domestic law. These differences were due to the degree of complexity resulting from the lack of a legislative body stricto sensu and of a judicial authority with universal power.
The universal community and the conscience of humanity became the recipients of the protection afforded by the international principle of legality. Thus, both the scope of such protection (from the local to the global) and its legal source to be applied and its drafter were modified.
Making legality more flexible, which implies a restriction of judiciable guarantees in favour of the fight against a criminality that affects all humanity, is justified by the fact that [international crimes] are usually backed or systematically committed by totalitarian States, which, of course, would not be interested in criminalizing their own acts.
The earliest experience of this more flexible principle of legality or of its redefinition within the international framework was during the Nuremberg trials …
For their part, the “Principles of international cooperation in the detection, arrest, extradition and punishment of persons guilty of war crimes and crimes against humanity” state:
1. War crimes and crimes against humanity, wherever they are committed, shall be subject to investigation and the persons against whom there is evidence that they have committed such crimes shall be subject to tracing, arrest, trial and, if found guilty, to punishment.
2. Every State has the right to try its own nationals for war crimes against humanity.
Thus, it is clear that, regardless of when the war crime was committed, it has to be prosecuted, but at the same time the State where the crime was committed is entitled to investigate it and, if necessary, impose the appropriate sanctions.
Thus, the principle of legality, in dealing exclusively with international crimes – aggression, war crimes, crimes against humanity and genocide – is redefined according to the sources of law, extending them, pursuant to article 38 of the [1945] Statute of the International Court of Justice, to treaties, custom, general principles of law, case law and international doctrine.
In this context of broadening the concept of law, it is important to recall that our country is a party to international conventions which provide for the punishment of international crimes, including grave breaches of international humanitarian law.
Those instruments were incorporated into the domestic legislation of our country, since Law 5 of 1960 approved the four 1949 Geneva Conventions, Law 11 of 1992 approved the [1977] Additional Protocol I and Law 171 of 1994 approved the [1977] Additional Protocol II.
Pursuant to articles 26 and 27 of the Vienna Convention on the Law of the Treaties of 23 May 1969, it is a principle of international law that provisions of domestic law cannot prevail over provisions of a treaty when it comes to relations between States Parties, and that a contracting party cannot invoke its own constitution or domestic legislation to evade its obligations under international law to comply with the treaties in force.
Moreover, there have been numerous instances where, at the international level, punishments have been applied in cases of international crimes without [corresponding] local legislation. This has built international custom and jurisprudence, clarifying the scope of the principle of legality in this context, beginning with the trials in Nuremberg and Tokyo, which inaugurated so-called international justice, aimed at the protection of humanity.
Also, Cambodia … suffered the tyranny of the Marxist-Leninist-Maoist regime of the Khmer Rouge, with the dictatorship of Saloth Sar (called Pol Pot), between 17 April 1975 and 6 January 1979, which was called Democratic Kampuchea and during which at least one third of the population was exterminated. In 2006, at the request of the UN, extraordinary chambers were set up to try these crimes. One of these chambers issued, on 26 July, the first instance judgment against Kaing J.C. Eav … convicting him as a leader of the regime, despite the lack of domestic legislation establishing that the atrocities committed against the population were considered international crimes.
In Europe as well, the European Court of Human Rights in Strasbourg has made it clear in several judgments that, in terms of the principle of legality, the applicable law extends not only to those rules written in the domestic order but also to unwritten rules, making express reference to jurisprudence, custom and international doctrine.
In that regard, when it comes to international crimes, legality involves incorporating international treaties into domestic legal systems with full effect as prior law in order to make it possible to impose sanctions, even if they were not provided for under the domestic legislation at the time of their commission, as concluded in cases brought by the Supreme Courts of Justice of Uruguay, Argentina, Chile, Peru and others.
Another source limiting the principle of legality in the Southern Cone countries comes as the result of the ruling issued by the Inter-American Court of Human Rights on 14 March 2001 in the Barrios Altos case … in which the Court found the Peruvian amnesty and “Full Stop Law” to be incompatible with the Pact of San Jose, as such law was intended to guarantee impunity for crimes committed by bodies or agents of the State. This has opened the way for new judgments of international crimes in the region.
In this context, the Supreme Court of Justice of Argentina, in the so-called “Simón case”, issued a judgment on 14 June 2005 removing the effects of “Full Stop” and obedience laws … which favoured impunity for crimes committed during the periods of the military dictatorships … In this judgment, the Court validated the use of an ex post facto international instrument, such as the [1994] Inter-American Convention on Forced Disappearance of Persons, as the basis for conviction.
Therefore, it can be affirmed that it is not possible to refrain from punishing international crimes under the justification of an omission in domestic legislation. This doctrine was built on cases in which it was well-known that the perpetrators exerted influence over the legislators who, owing to intimidation, connivance or simple lack of interest, abstained from incorporating the criminalization of such conduct into domestic legislation.
In this sense, even before the existence of international law punishing war crimes, it was predictable that such crimes would be provided for, according to the European Court of Human Rights judgment of 17 May 2010 in the Vassili Kononov case concerning a former Soviet military officer who was convicted by a Latvian tribunal in 2004, a decision subsequently endorsed by the Strasbourg Court.
It is important to emphasize that such flexibility of the principle of legality is applicable only to the four categories of the so-called international crimes, namely genocide, crime of aggression, crimes against humanity and violations of international humanitarian law.
This Chamber has recently addressed this issue and has recognized international treaties to which our State is a party as sources of criminal law regardless of the absence of a domestic law incorporating them. Therefore, since the entry into force of a treaty, it is legitimate to punish the conduct it provides for, as its provisions are considered to have been incorporated into the domestic legal order.
Thus, as … the four 1949 Geneva Conventions and their Additional Protocols have the status of international human rights treaties, they are automatically incorporated into domestic legislation, since all the steps required at the national level have been taken.
… [I]t does not matter that the law criminalizing violations of international humanitarian law has a temporal limitation starting on 25 July 2001. As the relevant international treaties were signed and ratified by our country, the obligation of positivization and sanction was established. 
Colombia, Supreme Court of Justice, Juancho Dique case, Judgment, 16 December 2010, pp. 12–13, 22–26 and 28–35.
[footnotes in original omitted; emphasis in original]