Related Rule
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]