judge must substantiate his decision on the factual and objective circumstances of the specific case, 83 which is for the prosecutor to prove and not the accused, 84 who must also be afforded the possibility of the right to an adversarial procedure and to be duly assisted by a lawyer. The Court has also held that the gravity of the offense is not, per se, a sufficient justification for pre-trial detention. 85 109. Finally, the Court has already indicated, with respect to the manner in which the elements that make up the legitimate purposes must be proved, that “the risk of flight cannot solely be measured taking into consideration only the gravity of the offence. It must be evaluated with reference to a series of other relevant factors that can confirm the existence of a risk of flight, as for example those related to a fixed residence, job, belongings, family and all types of ties to the country in which he or she is being tried.” 86 The European Court has also held that the danger that the accused obstruct the adequate development of the proceedings cannot be abstractly inferred, but rather it must be be supported by objective evidence, for example the risk of tampering witnesses or belonging to a criminal organization or a gang. 87 110. With respect to necessity, the Court finds that, since the deprivation of liberty is a measure that implies a restriction to an individual’s sphere of action, the judicial authority can only impose such a measure when it finds that the other legal mechanisms with a less burdensome effect on individual rights are not sufficient to satisfy the procedural objective. 88 111. The European Court has also held that alternative measures should be available and that a measure that restricts liberty may only be imposed when it is not possible to use alternative measures to mitigate its effects; it has also stated that the authorities must consider alternative measures to ensure appearance for trial. 89 For its part, in the Universal System of Protection of Human Rights, the United Nations Standard Minimum Rules for Non-custodial Measures refer to pre-trial detention as a last resort and clarify that “[p]re-trial detention shall be used as a means of last resort in criminal proceedings, with due regard for the investigation of the alleged offence and for the protection of society and of the victim.” It added that alternatives to pre-trial detention shall be applied at as early a stage as possible.” 90 112. The Court has also held that, in cases in which measures that restrict liberty are imposed, Article 7(5) establishes time limits on their length; therefore, when the period of pre-trial detention is no longer reasonable, the liberty of the accused should be limited by other less burdensome measures to ensure appearance at trial. The criteria that can be used to determine the reasonability of the period must be strictly related to the particular circumstances of the specific case. In view of the above and in the light of the provisions of Articles 7(3), 7(5) and 8(2) (presumption of innocence) the Court 83 Cf. Case of Amrhein et al. v. Costa Rica, supra, para. 357 and Case of Hernández v. Argentina, supra, para. 109. 84 Cf. Case of Romero Feris v. Argentina, supra, para. 101 and Case of Villarroel Merino et al. v. Ecuador, supra, para. 93. 85 Cf. Case of Bayarri v. Argentina. Preliminary Objection, Merits, Reparations and Costs. Judgment of October 30, 2008. Series C No. 187, para. 74 and Case of Villarroel Merino et al. v. Ecuador, supra, para. 91. 86 Cf. Case of Romero Feris v. Argentina, supra, para.105. Similarly, ECHR. Case of Idalov v. Russia, Judgment of May 22, 2012, Application No. 5826/03, para. 145; Case of Panchenko v. Russia, Judgment of June 11, 2005, Application No. 11496/05, paras. 102 and 106; Case of Becciev v. Moldavia, Judgment of October 4, 2005, Application No. 9190/03, para. 58, and Case of Sulaoja v. Estonia, Judgment of May 15, 2005, Application No. 55939/00, para. 64. 87 Cf. Case of Romero Feris v. Argentina, supra, para. 105. Similarly, ECHR. Case of Jarzyński v. Poland, Judgment of October 4, 2005, Application No. 15479/02, para. 43, Case of Podeschi v. San Marino, Judgment of April 13, 2017, Application No. 66357/14, para. 149 and Case of Štvrtecký v. Slovakia, Judgment of June 5, 2018, Application No. 55844/12, para. 61 Cf. Case of Chaparro Álvarez and Lapo Íñiguez v. Ecuador, supra, para. 93; Case of Amrhein et al. v. Costa Rica, supra, para. 356 and Case of Romero Feris v. Argentina, supra, para. 106. 88 Cf. Case of Romero Ferisvs. Argentina, supra, para.107. Similarly, Council of Europe, Committee of Ministers, Recommendation CM/Rec (2006) 13 on pre-trial detention, the conditions in which it takes place and the guarantees against its abuse, September 27, 2006, para. 3; ECHR. Case of Idalov v. Russia, Judgment of May 22, 2012, Application No. 5826/03, para.140 and Case of Aleksandr Makarov v. Russia, Judgment of March 12, 2009, Application No. 15217/07, para.139. 89 90 Case of Romero Feris v. Argentina, supra, para. 108. Similarly: United Nations, General Assembly, UN Standard Minimum Rules for Non-custodial Measures (The Tokyo Rules), Resolution 45/110, December 14, 1990, Rule 6(1) and (6)2. 27