- 53 - doing so,209 an analysis of the effectiveness of criminal proceedings and of access to justice can lead the Court, in cases of serious human rights violations, to examine the proportionality between the State’s response to the unlawful conduct of a State agent and the legal right allegedly affected by the human rights violation. Under the rule of proportionality, in the exercise of their obligation to prosecute such serious violations, States must ensure that the sentences imposed and their execution do not constitute factors that contribute to impunity, taking into account aspects such as the characteristics of the crime, and the participation and guilt of the accused.210 Indeed, there is an international legal framework which establishes that the punishments established for crimes involving acts that constitute serious human rights violations must be appropriate to their gravity.211 151. Regarding the punishment imposed, the perpetrators, as co-authors of the crime of first degree murder, were sentenced to the principal punishment of 43 years’ real imprisonment, and 10 years of loss of civil rights as an accessory penalty, and this was confirmed in its entirety by the appeals court. Subsequently, in March212 and June 2006,213 the convicted men obtained a reduction of sentence to 26 years, 10 months and 15 days. Finally, owing to benefits granted while they were serving their sentences, Zuñiga Labrador was granted release on parole in March 2006,214 and Medina Camacho in May 2007.215 Hence, in reality they served sentences of 11 years and 72 days, and 12 years and 122 days imprisonment, respectively, and are currently at liberty. 209 Cf. Vargas Areco v. Paraguay. Merits, reparations and costs. Judgment of September 26, 2006. Series C No. 155, para. 108, and Case of Usón Ramírez v. Venezuela, supra note 54, para. 87. 210 Cf. Hilaire v. Trinidad and Tobago. Preliminary objections. Judgment of September 1, 2001. Series C No. 80, paras. 103, 106 and 108; Case of Heliodoro Portugal v. Panama, supra note 51, para. 203; Case of Boyce et al. v. Barbados, supra note 36, para. 50; Case of the La Rochela Massacre v. Colombia, supra note 16, para. 196; Raxcacó Reyes v. Guatemala. Interpretation of the judgment on merits, reparations and costs. Judgment of February 6, 2006. Series C No. 143, para. 81, and Case of Vargas Areco v. Paraguay, supra note 209, para. 108. Similarly, Advisory Opinion OC-3/83 of September 8, 1983. Series A No. 3, para. 55. 211 Thus, the Principles on the Effective Prevention and Investigation of Extra-legal, Arbitrary and Summary Executions stipulated that “Governments […] shall ensure that any [extra-legal, arbitrary and summary] executions are recognized as offences under their criminal laws, and are punishable by appropriate penalties which take into account the seriousness of such offences” (Principle 1). Furthermore, with regard to torture and forced disappearance, the regional and international instruments establish specifically that the State must, in addition to recognizing them as offenses under their criminal laws, punish them and impose “severe penalties that take into account their serious nature” (article 6, Inter-American Convention to Prevent and Punish Torture) or “an appropriate punishment commensurate with its extreme gravity” (article III, Inter-American Convention on Forced Disappearance of Persons). Likewise, the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment stipulates that “[e]ach State Party shall make these offences punishable by appropriate penalties which take into account their grave nature” (article 4(2)). 212 Cf. Decision on recalculation of sentence based on the most favorable law (law 599 of 2000), in favor of Justo Gil Zuñiga Labrador issued by the Fourth Court for Execution of Sentences and Security Measures of Ibagué, Tolima, on March 31, 2006, in Investigation No. 2001-1374-110013107003-1999-5393 (evidence file, tome IX, attachment 147 to the brief with pleadings, motions and evidence, folios 4258 to 4260). 213 Cf. Decision on recalculation of sentence based on the most favorable law (law 599 of 2000), in favor of Hernando Medina Camacho issued by the Fourth Court for Execution of Sentences and Security Measures of Ibagué, Tolima, on June 8, 2006, in Investigation No. 2001-1374-110013107003-1999-5393 (evidence file, tome IX, attachment 149 to the brief with pleadings, motions and evidence, folios 4269 to 4271). 214 Cf. Note No. 38533/2020 of the Fourth Court for Execution of Sentences and Security Measures of August 21, 2007 (evidence file, tome XV, attachment 21 to the brief in answer to the application, folios 6772 to 6774). 215 Cf. Note No. 38533/2020 of the Fourth Court for Execution of Sentences and Security Measures of August 21, 2007, supra note 214, folios 6772 to 6774.