50 j) The judges responsible for the trial had been judges long before their appointment as “faceless” judges in any specific case. Their appointment is not based on the criteria of the individual who will be tried, but on “subspecialization within the courts”; k) Law No. 26,671 tacitly annulled article 15 of Decree Law No. 25,475, as well as all those provisions that, similarly, prevented defendants from knowing the identity of those who were participating in their trial; l) Legislative Decree No. 926 ordered the annulment of oral proceedings and judgments in which the prohibition to challenge judges, established in article 13(h) of Decree Law No. 25,475, declared unconstitutional by the judgment of the Constitutional Court of January 3, 2003, had been applied; m) Article 13(a) of Decree Law No. 25,475 does not make “a statement of criminal liability” by making it obligatory to open a pre-trial investigation with a detention order. The detention order, or preventive detention, is not a punishment, because it is an exceptional precautionary measure; n) The restriction of the right to question witnesses who took part in the preparation of the police deposition established in article 13(c)) of Decree Law No. 25,475 is designed to protect the lives and safety of members of the Peruvian National Police and their families; and o) The Peruvian Constitution establishes, as do the principal international instruments for the protection of human rights, that criminal trials must essentially be of a public nature, with the exceptions established by law in the interests of justice. In this regard, interpretatively, trials that affect State security should not be public. Considerations of the Court 77. Article 9 of the American Convention establishes that: No one shall be convicted of any act or omission that did not constitute a criminal offense, under the applicable law, at the time it was committed. A heavier penalty shall not be imposed than the one that was applicable at the time the criminal offense was committed. If subsequent to the commission of the offense the law provides for the imposition of a lighter punishment, the guilty person shall benefit therefrom. 78. First, it should be noted that the Inter-American Commission and the representatives have alleged that the definition of the crime of terrorism in article 2 of Decree Law No. 25,475 violates the principle of legality embodied in Article 9 of the American Convention (supra paras. 74(e), (g) and (h), and 75(b)). In this regard, the Court observes that article 2 of Decree Law No. 25,475 (crime of terrorism) was not applied in the proceeding against the alleged victim; consequently, this Court will not examine it and will proceed to consider the arguments presented by the parties in relation to article 4 of this Decree Law (crime of acts of collaboration with terrorism). 79. Concerning the principle of legality in the penal sphere, the Court has indicated that the elaboration of criminal categories involves a clear definition of the criminalized conduct, establishing its elements, and the factors that distinguish it