decision to be known, in order to rule out any indication of arbitrariness. 100 It must also show that the arguments of the parties have been duly taken into account and that the body of evidence has been studied. 69. Moreover, this Court has stipulated that, although deprivation of liberty may seek a legitimate purpose and be appropriate to achieve this, on combining the criteria developed and based on the principle of the best interest of the child, the deprivation of liberty of children based exclusively on migratory reasons exceeds the requirement of necessity, 101 because this measure is not absolutely essential in order to ensure their appearance at the immigration proceedings or to guarantee the implementation of a deportation order. Adding to this,the Court finds that the deprivation of liberty of a child in this context can never be understood as a measure that responds to the child’s best interest. Thus, the Court considers that measures exist that are less severe and that could be appropriate to achieve such an objective and, at the same time, satisfy the child’s best interest. In sum, the Court finds that the deprivation of liberty of a child migrant in an irregular situation, ordered on this basis alone, is arbitrary and, consequently, contrary to the Convention. 102 70. In addition, the Court has recognized that, in immigration matters, a child’s right to the protection of the family and, in particular, to enjoy family life preserving family unity insofar as possible, should always be given prevalence, except in those cases in which the separation of the child from one or both parents would be necessary owing to the best interest of the child. However, the child’s right to family life per se does not override the authority of the States to implement their own immigration policies in keeping with human rights, in the context of proceedings relating to the expulsion of one or both parents. 103 Therefore, to determine whether an immigration measure that may imply the separation of children from their family complies with the terms of the Convention, an assessment must be made of whether it is: established by law, and complies with the requirements of (a) suitability; (b) necessity, and (c) proportionality; in other words, it must be necessary in a democratic society. 104 71. However, in this regard this Court has established that in those situations in which the child has a right to nationality – original, by naturalization, or for any other reason established in domestic law – of the country from which one or both of the parents may be expelled owing to their irregular migratory situation, or in which the child complies with the legal conditions to reside there on a permanent basis, it is axiomatic that the child must conserve the right to continue enjoying her or his family life in said country and, as a component of this, mutual enjoyment of the cohabitation of parents and children. The Court has found that the rupture of the family unit by the expulsion of one or both parents due to a breach of immigration laws related to entry or permanence is disproportionate in these situations, because the sacrifice inherent in the restriction of the right to family life, which may have repercussions on the life Cf. Case of Claude-Reyes et al. v. Chile. Merits, reparations and costs. Judgment of September 19, 2006. Series C No. 151, para. 122, and Case of Pávez Pávez v. Chile. Merits, reparations and costs. Judgment of February 4, 2022. Series C No. 449, para. 154. 100 101 Cf. Case of Vélez Loor v. Panama, supra, para. 166, and Advisory Opinion OC-21/14, supra, para. 154. 102 Cf. Advisory Opinion OC-21/14, supra, para. 154. 103 Cf. Advisory Opinion OC-21/14, supra, para. 274. 104 Cf. Advisory Opinion OC-21/14, supra, para. 275. 24