37 guarantees may subvert the rules of law and deprive the detainees of legal protection.80 60. Article 7(2) of the Convention establishes the material and formal conditions for the deprivation of liberty.81 61. Article 84 of the Political Constitution in force when Mr. Alfredo López Álvarez was detained establishes that [n]obody may be arrested or detained if not in virtue of a written order issued by a competent authority, issued with the legal formalities and due to a motive previously established by Law. However, the infraganti criminal may be arrested by any person with the only effect of handing him over to the authorities. The person arrested or detained must be informed in the act and with clarity of his rights and of the charges against him; and the authorities must also allow them to communicate the arrest to a family member or person of their choice. 62. Article 11 of the Code of Criminal Procedures, Decree No. 189 of 1984, in force at the time of the facts, established that [t]he infranganti criminal may be arrested by any person with the sole effect of handing him over to the authorities. The person arrested or detained must be informed in the act with all clarity of his rights and of the charges against him; and the authorities must also allow him to communicate his arrest to a family member or a person of his choice. An infraganti criminal will be understood as a person found in the act itself of committing a crime or that has just committed it, or when he is still being chased by the roar of the crowd as author or accomplice, or he is surprised with the weapons, instruments, or documents that imply said participation. […] 63. Pursuant to that mentioned in Articles 84 of the Constitution and 11 of the Code of Criminal Procedures, in force at the time of the facts, it can be concluded that in order to arrest a person there must be an arrest warrant, except when dealing with a crime detected in the act. 64. In a legitimate in flagrante arrest it is precise that there be an immediate judicial control of said arrest, in order to avoid the arbitrariness or illegality of the measure. 65. In the present case, according to the facts established (supra para. 54(11)), Mr. Alfredo López Álvarez was detained in conditions that let us reasonably assume, the flagrantness required for that purpose by the domestic law, taking into account that the arrest coincided with the seizure of a substance that appeared to be an illegal drug by the State agents; therefore, the arrest in itself was not illegal. * * * 66. Article 7(3) of the Convention prohibits the arrest or imprisonment by methods that although qualified as legal, may in the practice result unreasonable or out of 80 Cf. Case of García-Asto and Ramírez-Rojas, supra note 7, para. 104; Case of Acosta-Calderón, supra note 18, para. 56, and Case of Tibi. Judgment of September 7, 2004. Series C No. 114, para. 97. 81 Cf. Case of García-Asto and Ramírez-Rojas, supra note 7, para. 105; Case of Palamara-Iribarne, supra note 15, para. 196, and Case of Acosta-Calderón, supra note 18, para. 57.