73. Had these been the grounds for the arrest, the Commission recalls that the Court has held that the requirement for making an exception under the law that curtails the right to personal liberty in accordance with Article 7(2) of the Convention is to issue a statutory description of the criminal offense, as specifically as possible, and establish “beforehand” the “grounds” for which, and the “conditions” in which, a person may be physically deprived of their liberty. Thus, any requirement established under domestic law that is not abided by when an individual is deprived of his or her liberty renders such a deprivation illegal and a violation of the American Convention.69 74. As stated in merit reports 66/01 and 40/14, the grounds of “serious presumption of responsibility” are not set forth in the Constitution.70 Moreover, it opens the door to police officers making arrests based not on objective criteria, but rather on what he or she understands as a “serious presumption of responsibility” leaving “the definition to the discretion of the police officer making the arrest.”71 75. In said report, the Commission considered that this provision “contravenes the Convention” since “it leaves the decision as to the appropriateness of the arrest to the subjective judgment of the police officer carrying out the arrest.”72 The Commission understood that the requirement for a statutory description of a crime in order to restrict personal liberty, “is not satisfied by a vague and general prescription such as ‘serious presumption of responsibility.”73 76. Based on the foregoing, the Commission concludes that based on the available information, the arrest was carried out without an arrest warrant in keeping with domestic law or in a situation of flagrante delicto. Moreover, were the grounds for the arrest a serious presumption of responsibility, the Commission reiterates that said provision is in and of itself inconsistent with the principle of legality as it concerns personal liberty. Therefore, the Commission considers that the State of Ecuador violated Articles 7(1) ad 7(2) of the Convention with respect to the obligations set forth under Articles 1(1) and 2 thereof, to the detriment of Mario Montesinos Mejía. 2. The right not to be arbitrarily deprived of liberty and considerations on the length of pretrial detention 77. The Inter-American Commission and Court have held that pretrial detention is limited by the principles of legality, presumption of innocence, necessity, and proportionality.74 The Court has also stated that it is a precautionary, rather than a punitive,75 measure, and that, as the most severe measure that can be imposed on an accused, it should only be used exceptionally. In the view of both organs of the inter-American system, the rule should be for the accused to be on release until a decision is reached on their criminal responsibility.76 69 I/A Court H.R. Case of Chaparro Álvarez and Lapo Íñiguez. v. Ecuador. Preliminary Objections, Merits, Reparations, and Costs. Judgment of November 21, 2007. Series C No. 170, paragraph 55. 70 IACHR, Report No. 66/01, Case 11.992, Merits, Dayra María Levoyer Jiménez, Ecuador, June 14, 2001, paragraph 36; and Report No. 40/14, Case 11.438, Merits, Herrera Espinoza et al., Ecuador, July 17, 2014, paragraph 120. 71 IACHR, Report No. 66/01, Case 11.992, Merits, Dayra María Levoyer Jiménez, Ecuador, June 14, 2001, paragraph 36; and Report No. 40/14, Case 11.438, Merits, Herrera Espinoza et al., Ecuador, July 17, 2014, paragraph 120. 72 IACHR, Report No. 66/01, Case 11.992, Merits, Dayra María Levoyer Jiménez, Ecuador, June 14, 2001, paragraph 37; and Report No. 40/14, Case 11.438, Merits, Herrera Espinoza et al., Ecuador, July 17, 2014, paragraph 121. 73 IACHR, Report No. 66/01, Case 11.992, Merits, Dayra María Levoyer Jiménez, Ecuador, June 14, 2001, paragraph 37; and Report No. 40/14, Case 11.438, Merits, Herrera Espinoza et al., Ecuador, July 17, 2014, paragraph 121. 74 IACHR, Report on the Use of Pretrial Detention in the Americas, OEA/Ser.L/V/II. December 30, 2013, paragraph 20; I/A Court H.R., Case of López Álvarez v. Honduras, Judgment of February 1, 2006, Series C No. 141, paragraph 67; Case of García Asto and Ramírez Rojas v. Peru, Judgment of November 25, 2005, Series C No. 137, paragraph 106; Case of Palamara Iribarne v. Chile, Judgment of November 22, 2005, Series C No. 135, paragraph 197; and Case of Acosta Calderón v. Ecuador, Judgment of June 24, 2005, Series C No. 129, paragraph 74. 75 I/A Court H.R., Case of Suárez Rosero v. Ecuador. Merits. Judgment of November 12, 1997. Series C No. 35, paragraph 77. 76 IACHR, Report on the Use of Pretrial Detention in the Americas, OEA/Ser.L/V/II. December 30, 2013, paragraph 21; I/A Court H.R., Case of López Álvarez v. Honduras, Judgment of February 1, 2006, Series C No. 141, paragraph 67; I/A Court H.R., Case of Palamara Iribarne v. Chile, Judgment of November 22, 2005, Series C No. 135, paragraph 196; and I/A Court H.R., Case of Acosta Calderón v. Ecuador, Judgment of June 24, 2005, Series C No. 129, paragraph 74. 13