22 BOUYID v. BELGIUM JUDGMENT the European Code of Police Ethics (cited above) and the European Prison Rules (to which the Court and the CPT referred in their work), as well as the Organization for Security and Co-operation in Europe’s Guidebook on Democratic Policing. It derived the following principles from those texts: everyone had the right not to be subjected to torture, cruel, inhuman or degrading treatment or punishment, as the UN Body of Principles for the Protection of All Persons under Any Form of Detention or Imprisonment specified that these terms should be interpreted so as to extend the widest possible protection against abuses; non-violent means should be attempted first; force should be used only when strictly necessary, and solely for lawful law-enforcement purposes; in their relations with persons in detention, law-enforcement officials should not use force, except when strictly necessary for the maintenance of security and order within the institution, or when personal safety was threatened; no exceptions or excuses should be allowed for unlawful use of force; the use of force was always to be proportionate to lawful objectives; restraint should be exercised in the use of force; damage and injury should be minimised; a range of means for differentiated use of force should be made available; all law-enforcement officials should be trained in the use of the various means for differentiated use of force; and all officers should be trained in the use of non-violent means. 78. The third-party intervener stated that the principle established by the Court to the effect that any recourse to force by a State agent against a person deprived of his liberty which had not been made strictly necessary by that person’s conduct diminished human dignity and was in principle an infringement of the right set forth in Article 3. This principle was also enshrined in the case-law of the Inter-American Court of Human Rights (it referred to Loayza-Tamayo v. Peru (merits), judgment of 17 September 1997, § 57, Series C No. 33). Furthermore, the Court had specified that where the absence of such strict necessity had been established, there was no need to assess the severity of the suffering caused in order to find a violation of Article 3 (it referred to Keenan v. the United Kingdom, no. 27229/95, § 113, ECHR 2001-III); where such necessity had been established, all the decisive factors were taken into account, including the duration of the treatment, its physical and/or mental effects and, in some cases, the sex, age and state of health of the victim, as well as his or her particular vulnerability; and detained persons were vulnerable because they were under the absolute control of the police or prison staff. The third-party intervener added that in a judgment of 2 June 2010 (no. 543/2010) the Spanish Supreme Court, taking into account this vulnerability, had ruled that a slap administered by a police officer to a detainee had been humiliating and degrading despite the lack of any visible injury. This approach had also been adopted by the previous Special Rapporteur on the Promotion and Protection of Human Rights and Fundamental Freedoms