8 21. For more than two decades, the bodies of the Inter-American system have interpreted and applied the principles discussed above, establishing the following standards: (i) pretrial detention should be the exception, not the rule; (ii) the legitimate and permissible purposes of pretrial detention should be of a procedural nature, such as to avoid risk of flight or hampering of the course of proceedings; (iii) consequently, the existence of probable cause of criminal acts is insufficient grounds to order the pretrial detention of a person; (iv) even when there are procedural purposes for it, pretrial detention must be absolutely necessary and proportional, meaning that there should not be any other less restrictive means available to achieve the procedural purpose that is being pursued and that personal liberty should not be disproportionately affected; (v) all of the aforementioned aspects must be grounded in particular facts and not be supported by presumption; (vi) pretrial detention must be issued for the length of time strictly necessary to fulfill the procedural purpose and, therefore, requires periodic review of the elements that supported its application; (vii) holding a defendant in pretrial detention for an unreasonable length of time is tantamount to an anticipated prison sentence; and, (viii) in the case of children and adolescents, the criteria for ordering pretrial detention should be applied with greater rigor, with preference given to the use of other precautionary measures or prosecuting while the accused is at liberty, and, when it is applicable, it must be ordered for the shortest time possible. 22. In the Principles and Best Practices on the Protection of Persons Deprived of Liberty, the Commission reaffirms these fundamental standards concretely as follows: Preventive deprivation of liberty is a precautionary measure, not a punitive one, which shall additionally comply with the principles of legality, the presumption of innocence, need, and proportionality, to the extent strictly necessary in a democratic society. It shall only be applied within the strictly necessary limits to ensure that the person will not impede the efficient development of the investigations nor will evade justice, provided that the competent authority examines the facts and demonstrates that the aforesaid requirements have been met in the concrete case. (Principle III.2). 23. As for the contents of this report, Chapter II offers an analysis of pretrial detention in the region, paying particular attention to the reasons why this measure is not used solely on an exceptional basis. It presents a summary of the main determinations issued by the Inter-American Commission and monitoring mechanisms of the universal system, it cites official statistics provided by States on the use of pretrial