BOUYID v. BELGIUM JUDGMENT 23 while Countering Terrorism, the CPT and the UN Human Rights Committee. 79. The third-party intervener stressed that child detainees were doubly vulnerable, as pointed out by the UN Special Rapporteur on Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment. With reference to the UN Rules for the Protection of Juveniles Deprived of their Liberty and the work of the UN Committee on the Rights of the Child, the third-party intervener added that it was well established that the use of force against children was prohibited save for a very limited number of purposes. That applied to all forms of violence, including non-physical or unintentional violence, whatever their frequency or severity, and even where they were not motivated by intent to harm. Like the CPT in its ninth general activity report, it condemned in particular the “pedagogical use of force” (especially “pedagogical slaps”), which consisted in using force in response to a refusal to cooperate or bad behaviour, while the CPT also noted that police stations were the places where young people ran the greatest risk of deliberate ill-treatment. 80. Lastly, the third-party intervener pointed out that national legal systems reflected international and regional standards. The prohibition of the use of force except where it was strictly necessary was also enshrined in the United Kingdom, Sweden, Australia, Canada and the United States. C. The Court’s assessment 1. The substantive aspect of the complaint (a) General principles 81. Article 3 of the Convention enshrines one of the most fundamental values of democratic societies (see, among other authorities, Selmouni v. France [GC], no. 25803/94, § 95, ECHR 1999-V; Labita v. Italy [GC], no. 26772/95, § 119, ECHR 2000-IV; Gäfgen v. Germany [GC], no. 22978/05, § 87, ECHR 2010; El-Masri v. the former Yugoslav Republic of Macedonia [GC], no. 39630/09, § 195, ECHR 2012; and Mocanu and Others v. Romania [GC], nos. 10865/09 and 2 others, § 315, ECHR 2014). Indeed the prohibition of torture and inhuman or degrading treatment or punishment is a value of civilisation closely bound up with respect for human dignity. Unlike most of the substantive clauses of the Convention, Article 3 makes no provision for exceptions, and no derogation from it is permissible under Article 15 § 2 even in the event of a public emergency threatening the life of the nation (see Mocanu and Others, cited above, § 315). Even in the most difficult circumstances, such as the fight against terrorism and organised crime, the Convention prohibits in absolute terms torture and inhuman or degrading treatment or punishment, irrespective of the conduct