51 under its custody. State authorities exercise total control over persons under their custody. The way a detainee is treated must be subject to the closest scrutiny, taking into account the detainee’s vulnerability;81 this guarantee function of the State is especially important when the detainee is a minor. This circumstance gives the State the obligation to exercise its function as guarantor taking all care required by the weakness, the lack of knowledge, and the defenselessness that minors naturally have under those circumstances. 127. Vulnerability of the detainee worsens when the detention is illegal or arbitrary. Then the person is in a situation of complete defenselessness, which causes a definite risk of abridgment of other rights, such as those to humane and decent treatment.82 The State must provide a satisfactory explanation for what has happened to a person whose physical conditions were normal when custody began,83 and during it or at the end of it they worsened. The State is also “under the obligation to create the necessary conditions for any remedy [in favor of the detainee] to be able” to attain effective results.84 This Court has emphasized that solitary confinement of the detainee must be exceptional, as it causes him or her moral suffering and psychological disturbances, as it places the detainee in an especially vulnerable situation and increases the risk of aggression and arbitrary treatment in prisons,85 and because it endangers strict observance of due legal process. 128. Likewise, the detainee and those with legal custody or representation of the detainee have the right to be informed of the causes and reasons for his or her detention at the time it occurs, which “constitutes a mechanism to avoid illegal or arbitrary detentions from the very moment of imprisonment and, at the same time, ensures the individuals right to defense”86 and it also contributes, in the case of a minor, to lessen the impact of detention insofar as possible. 129. Another measure that seeks to prevent arbitrary treatment or illegality is immediate judicial control, taking into account that under the rule of law the judge must guarantee the rights of the detainee, authorize taking precautionary or coercive measures, when strictly necessary, and generally seek a treatment that is consistent with the presumption of innocence in favor of the accused until his or her responsibility has been proven. “[A]n individual who has been imprisoned with no 81 Cf. Eur. Court HR, Iwanczuk v. Poland (App. 25196/94) Judgment of 15 November 2001, para. 53. 82 Cf., Juan Humberto Sánchez Case, supra note 4, para. 96; Bámaca Velásquez Case, supra note 30, para. 150; and Cantoral Benavides Case, supra note 30, para. 90. 83 Cf., Juan Humberto Sánchez Case, supra note 4, para. 100. Likewise, Cf., Eur. Court HR, Salman v. Turkey judgment of 27 June 2000, Reports of Judgments and Decisions 2000-VII, para. 98; Eur. Court HR, Timurtas v. Turkey judgment of 13 June 2000, Reports of Judgments and Decisions 2000-VI, para. 82; Eur. Court HR, Selmouni v. France judgment of 28 July 1999, Reports of Judgments and Decisions 1999-V, para. 87; Eur. Court HR, Ribitsch v. Austria, supra note 78, para. 34; and Eur. Court H. R., Case of Tomasi v. France, supra note 78, paras. 108-110. 84 Cf., Juan Humberto Sánchez Case, supra note 4, para. 85; Bámaca Velásquez Case, supra note 30, para. 194; and “White Van” Case (Paniagua Morales et al.), supra note 30, para. 167. 85 Cf., Bámaca Velásquez Case, supra note 30, para. 150; Cantoral Benavides Case, supra note 30, para. 82; and “Street Children” Case (Villagrán Morales at al.), supra note 69, para. 164. 86 Cf., Juan Humberto Sánchez Case, supra note 4, para. 82.