33 treaty-based law. If it is proved that the State did not inform the person of the “reasons” for his detention and failed to notify him of the “charges” against him, the detention would be unlawful and, consequently, contrary to Article 7(2) of the Convention, but it would also constitute a violation of the right embodied in Article 7(4) thereof.143 105. This Court has established that the information on the “motives and reasons” for the detention must be provided “when the detention takes place,” which “constitutes a mechanism to avoid unlawful or arbitrary detentions from the very instant of deprivation of liberty and, also, guarantees the right to defense of the individual detained.”144 In addition, the right to be informed of the reasons for the detention allows the person detained to contest its lawfulness, using the legal mechanisms that all States must offer, in the terms of Article 7(6) of the Convention. 106. The information on the motives and reasons for the detention necessarily supposes, first, providing information on the detention itself. The person detained must understand that he is being detained. Second, the agent carrying out the detention must inform him in simple language, free of technicalities, of the essential facts and legal grounds on which the detention is based. Article 7(4) of the Convention is not satisfied if only the legal grounds are mentioned.145 107. The first part of Article 7(5) of the Convention stipulates that a detention must be subject to prompt judicial review. The Court has understood that immediate judicial control is a measure intended to avoid arbitrary or unlawful detention, bearing in mind that, under the rule of law, the judge must guarantee the rights of the person detained, authorize the adoption of preventive or coercive measures when this is strictly necessary and, in general, ensure that the accused is treated in a manner consequent with the presumption of innocence.146 The European Court has ruled similarly and, in addition, has equated the term “promptly” with the term “immediately” and has established that flexibility in the interpretation of this term must be limited.147 This is so, given that pre-trial detention “is the most severe measure that can be applied to a person accused of a crime, so that its application must be exceptional in nature, limited by the principles of legality, the presumption of innocence, need and proportionality, all of which are strictly necessary in a democratic society,”148 because “it is a preventive rather than a punitive measure.”149 143 Cf. Chaparro Álvarez and Lapo Íñiguez v. Ecuador, supra note 36, para. 69. 144 Cf. Juan Humberto Sánchez v. Honduras. Preliminary objections, merits, reparations and costs. Judgment of June 7, 2003. Series C No. 99, para. 82, and Chaparro Álvarez and Lapo Íñiguez v. Ecuador, supra note 36, para 70. 145 Cf. Chaparro Álvarez and Lapo Íñiguez v. Ecuador, supra note 36, para. 71. 146 Cf. Bulacio v. Argentina. Merits, reparations and costs. Judgment of September 18, 2003. Series C No. 100, para. 129; Chaparro Álvarez and Lapo Íñiguez v. Ecuador, supra note 36, para. 81, and García Asto and Ramírez Rojas v. Perú, supra note 133, para. 109. 147 Eur. Court H.R., Brogan and Others v. The United Kingdom, judgment of 29 November 1988, Series A No 145-B, para. 59 148 Cf. Acosta Calderón v. Ecuador, supra note 135, para. 74; Servellón García et al. v. Honduras, supra note 39, para. 88, and García Asto and Ramírez Rojas v. Perú, supra note 133, para. 106. 149 Cf. Suárez Rosero v. Ecuador. Merits, supra note 47, para. 77; Chaparro Álvarez and Lapo Íñiguez v. Ecuador, supra note 36, para. 145, and López Álvarez v. Honduras. Merits, reparations and costs. Judgment of February 1, 2006. Series C No. 141, para. 69.