50 without any discrimination for reasons of race, color, sex, language, religion, political or other opinion, national or social origin, economic status, birth, or any other social condition. 221. Article 2 of the American Convention provides that: Where the exercise of any of the rights or freedoms referred to in Article 1 is not already ensured by legislative or other provisions, the States Parties undertake to adopt, in accordance with their constitutional processes and the provisions of this Convention, such legislative or other measures as may be necessary to give effect to those rights or freedoms. 222. The Inter-American Court has written that under the rule of law, the principles of legality and non-retroactivity govern the actions of all bodies of the State in their respective fields, particularly when the 174 exercise of its punitive power is at issue. It has also held that in a democratic system greater precautions must be taken to ensure that such measures are adopted with absolute respect for the basic rights of individuals, and 175 subject to careful verification to check for unlawful conduct. The principles recognized in Article 9 of the Convention of nullum crimen sine lege and nullum poena sine lege, prohibit states from prosecuting or punishing persons for acts or omissions that did not constitute criminal offenses, under applicable law, at the time they were committed.176 223. 224. The Commission understands that in the exercise of its criminal policy and based on its history, social and other considerations, it is, in principle, up to a State to determine which behaviors will be classified as crimes over which the State can exercise its punitive authority. However, certain elements can be extrapolated from Article 9 of the American Convention that the States must observe when exercising their power to determine what constitutes a crime. As it pertains to this case and as the case law of the inter-American system has established, the principle of legality has a corollary, which is that criminal law must be drafted without ambiguities and in rigorous, precise and unequivocal language that clearly defines the behaviors being classified as punishable offenses, while also stating what the elements and factors are that distinguish one behavior from other behaviors 177 that are not punishable offenses or are punishable as other criminal offenses. 225. The Commission has written that compliance with the principle of legality in criminal law allows 178 individuals to pattern their conduct to conform to the law. As the IACHR has held, “[t]he principle of legality has a specific role in the definition of crimes; on the one hand, it guarantees individual liberty and safety 174 I/A Court H.R., Case of Ricardo Canese v. Paraguay. Judgment of August 31, 2004. Series C No. 111, paragraph 177; I/A Court H.R., Case of Baena Ricardo et al. v. Panama. Judgment of February 2, 2001. Series C No. 72, paragraph 107; I/A Court H.R., Case of De la Cruz Flores v. Peru. Judgment of November 18, 2004. Series C No. 115, paragraph 80; .I/A Court H.R., Case of Fermín Ramírez. Judgment of June 20, 2005. Series C No. 126, paragraph 90; and I/A Court H.R., Case of García Asto and Ramírez Rojas v. Peru. Judgment of November 25, 2005. Series C No. 137, paragraph 187. 175 I/A Court H.R., Case of Baena Ricardo et al. v. Panama. Judgment of February 2, 2001. Series C No. 72, paragraph 106; Citing, inter alia, Eur. Court H.R., Ezelin, judgment of 26 April 1991, Series A no. 202, para. 45; and Eur. Court H.R., Müller and Others, judgment of 24 May 1988, Series A no. 133, para. 29. See also, I/A Court H.R., Case of De la Cruz Flores v. Peru. Judgment of November 18, 2004. Series C No. 115, paragraph 81; and I/A Court H.R., Case of García Asto and Ramírez Rojas v. Peru. Judgment of November 25, 2005. Series C No. 137, paragraph 189. 176 IACHR, Report on Terrorism and Human Rights, OEA/SER.L/V/II.116, Doc. 5 rev. 1, corr., October 22, 2002, paragraph 225. 177 IACHR, Report on the situation of human rights in Peru (2000), OEA/Ser.L./V/II.106, Doc. 59 rev. 2, June 2, 2000, paragraphs 80, 168; IACHR, Report on Terrorism and Human Rights, OEA/SER.L/V/II.116, Doc. 5 rev. 1, corr., October 22, 2002, paragraph 225; I/A Court H.R., Case of Castillo Petruzzi et al. Judgment of May 30, 1999 (Merits, Reparations and Costs), Series C No. 52, paragraph 121; I/A Court H.R., Case of Cantoral Benavides v. Peru. Judgment of August 18, 2000. Series C No. 69, paragraph 157; I/A Court H.R., Case of Ricardo Canese v. Paraguay. Judgment of August 31, 2004. Series C No. 111, paragraph 174; I/A Court H.R., Case of De la Cruz Flores v. Peru. Judgment of November 18, 2004. Series C No. 115, paragraph 79; I/A Court H.R., Case of García Asto and Ramírez Rojas v. Peru. Judgment of November 25, 2005. Series C No. 137, paragraph 188; I/A Court H.R., Case of Usón Ramírez v. Venezuela. Preliminary Objection, Merits, Reparations and Costs. Judgment of November 20, 2009. Series C No. 207, paragraph 55. 178 IACHR, Report on Terrorism and Human Rights, OEA/SER.L/V/II.116, Doc. 5 rev. 1, corr., October 22, 2002, paragraph 225, and Executive Summary, paragraph 17.