and under the conditions previously established by the Constitution or by a law established pursuant thereto (material aspect) and also strictly subject to the procedures objectively defined in the law (formal aspect)”104 96. With respect to the requirement of legality and the police powers to detain, the Court believes it relevant to recall that wrongful action by the police represents “one of the main threats to the right of personal liberty.”105 Therefore, the rules that determine police powers to prevent and investigate crimes must include specific and clear references to parameters that avoid arbitrary or unconstitutional detentions. 106 The detentions that occur without being en flagrante or without a judicial order must be exceptional107 and the lawfully established police powers must be interpreted restrictively. In order that a detention by the police without a judicial order be exceptional and strictly lawful, there is a legal obligation that the intervening officials clearly indicate the grounds and motives that, in applying the law, have justified the detention.108 97. It must be noted that the arbitrariness of a deprivation of liberty, which is protected by Article 7(3) of the Convention, is not only unlawful, but is also broader in that it includes elements of impropriety, injustice and unpredictability. Thus, the deprivation of liberty for “for grounds and by methods that, while classified as legal, could be deemed to be incompatible with the respect for the fundamental rights of the individual because it was, among others, unreasonable, unforeseeable or lacking in proportionality, would be arbitrary.”109 98. The Court has also pointed out that under Article 7 of the Convention in order that a preventive measure of deprivation of liberty related to a criminal proceeding is not arbitrary, the following parameters must be observed: i) that there are elements to formulate charges or to prosecute: there must exist sufficient indicia that allow the reasonable assumption that an unlawful act has occurred and that the person brought to trial Cf. Case of Gangaram Panday v. Suriname. Merits, Reparations and Costs. Judgment of January 21, 1994. Series C No. 16, para. 47 and Case of Fernández Prieto and Tumbeiro v. Argentina. Merits and Reparations. Judgment of September 1, 2020. Series C No. 411, para. 66. In the same sense, Case of Villarroel Merino et al. v. Ecuador, para. 84. As has been stated, the Court, in order to rule on the conventionality of a deprivation of liberty, must analyze whether the requirement of legality has been complied with. In doing so, the Court must rule in accordance with the Convention, since it is the Convention that refers to the domestic law. The Court is not conducting a control of constitutionality or of legality, but only of conventionality (Case of Azul Rojas Marín et al. v. Peru. Preliminary Objections, Merits, Reparations and Costs. Judgment of March 12, 2020. Series C No. 402, para. 110 and Case of Fernández Prieto and Tumbeiro v. Argentina, para. 66). 104 Case of Servellón García et al. v. Honduras. Judgment of September 21, 2006. Series C No. 152, para. 86 and Case of Fernández Prieto and Tumbeiro v. Argentina, para. 64. 105 106 Cf. In the same sense, Case of Fernández Prieto and Tumbeiro v. Argentina, para. 90. In this case, the Court indicated that “those provisions that include and enable conditions that permit a detention without a court order or in flagrante delicto, in addition to meeting the requirements of legitimate purpose, appropriateness and proportionality, must establish the existence of objective elements so that it is not mere police intuition or subjective criteria, that cannot be verified, that are the reasons for a detention.” 107 Cf. Case of Fernández Prieto and Tumbeiro v. Argentina, para. 92. 108 Cf. In the same sense, Case of Fernández Prieto and Tumbeiro v. Argentina, para. 97. 109 Case of Gangaram Panday v. Suriname, para. 47 and Case of Villarroel Merino et al. v. Ecuador, para. 86. 26