JALLOH v. GERMANY JUDGMENT 25 2. The Government 91. In the Government’s view, the administration of the emetics to the applicant had not contravened either Article 3 or Article 8 of the Convention. Consequently, the use of the drug bubble thereby obtained as evidence in the criminal proceedings against the applicant had not rendered his trial unfair. Determining the exact nature, amount and quality of the drugs being sold by the applicant had been a crucial factor in securing the applicant’s conviction and passing sentence. 92. The Government further submitted that the right not to incriminate oneself only prohibited forcing a person to act against his or her will. Provoking an emesis was a mere reaction of the body which could not be controlled by a person’s will, and was therefore not prohibited by the principle against self-incrimination. The suspect was not thereby forced to contribute actively to securing the evidence. The accused’s initial refusal to take the emetics could not be relevant, as otherwise all investigative measures aimed at breaking a suspect’s will to conceal evidence, such as taking blood samples by force or searching houses, would be prohibited. 93. Moreover, the Government argued that according to the Court’s judgment in Saunders, cited above, drugs obtained by the forcible administration of emetics were admissible in evidence. If it was possible to use bodily fluids or cells as evidence, then a fortiori it had to be possible to use objects which were not part of the defendant’s body. Furthermore, the administration of emetics, which the applicant merely had to endure passively, was not comparable to the administration of a truth serum as prohibited by Article 136a of the Code of Criminal Procedure, which broke the suspect’s will not to testify. B. The Court’s assessment 1. General principles established under the Court’s case-law 94. The Court reiterates that its duty, according to Article 19 of the Convention, is to ensure the observance of the engagements undertaken by the Contracting States to the Convention. In particular, it is not its function to deal with errors of fact or of law allegedly committed by a national court unless and in so far as they may have infringed rights and freedoms protected by the Convention. While Article 6 guarantees the right to a fair hearing, it does not lay down any rules on the admissibility of evidence as such, which is primarily a matter for regulation under national law (see Schenk v. Switzerland, 12 July 1988, §§ 45-46, Series A no. 140, and Teixeira de Castro v. Portugal, 9 June 1998, § 34, Reports 1998-IV). 95. It is therefore not the role of the Court to determine, as a matter of principle, whether particular types of evidence – for example, evidence