5.  The applicant was born in 1964. When lodging his application, he was detained in Saarbrücken Prison. 6.  In July 2007 the Zweibrücken Public Prosecutor’s Office was informed by a person, to whom they had guaranteed confidentiality and whose identity had remained unknown throughout the proceedings, that the applicant was selling large amounts of amphetamine. 7.  The Trier police therefore mandated another police informer, S., who was equally guaranteed confidentiality by the Zweibrücken Public Prosecutor’s Office and was supervised by police officer K., to test the veracity of these allegations. S. visited the applicant in his motorbike shop on 18 July 2007 and pretended being interested in buying a motorbike. He visited the applicant in the shop for the second time on 14 August 2007. On that occasion, the applicant told S. that a former member of his motorbike club “Bandidos” had cheated the club and offered S. 1,000 euros (EUR) if he would beat up that person. When the applicant showed S., who had disclosed his acquaintance with arms, his firearms and asked S. whether he could supply him with weapons, S. asked the applicant whether he could sell him amphetamine. The applicant asked in reply how much S. would need and what price he would be ready to pay. S. offered to pay EUR 4,000 per kilogram of amphetamine of a good quality. The applicant agreed to the offer and handed over to S. a sample of amphetamine which he had stored in a drawer of his garage. On 24 August 2007 S. again visited the applicant and offered purchasing 500 grams of amphetamine from the applicant, in accordance with the instructions from his supervising police officer. The applicant agreed to sell that amount of drugs at a price of EUR 2,000. He had carried a loaded revolver during all of his meetings with S. and had threatened S. with the revolver once, accusing him of being a traitor. 8.  On 27 August 2007 the Trier District Court authorised the participation of an undercover police officer, C., supervised by police officer L., in the operation. 9.  On 28 August 2007 S. bought 500 grams of amphetamine for EUR 2,000 from the applicant, who carried a loaded revolver during the transactions, handed it over to C. who was awaiting him at a different place and brought the money supplied by C. to the applicant. 10.  On 20 September 2007 S. again visited the applicant in his garage and told him that he would like to buy further drugs from him. The applicant thereupon asked S. whether he would need one kilogram or more. S. ordered 500 grams of amphetamine, in accordance with his instructions from police officer K., and announced that he would need higher amounts of drugs in the future. The applicant agreed to the proposals. 11.  On 4 October 2007 S. again bought 500 grams of amphetamine for EUR 2,000 in the presence of C. from the applicant, who carried a loaded revolver during the transaction. As advised by police officer K., S. then asked the applicant to supply a larger amount of drugs. The applicant explained that he could supply as much as S. wanted, five or ten kilograms. S. thereupon ordered 6.5 kilograms of amphetamine for which he was to pay EUR 26,000. 12.  On 16 October 2007 S. and C. bought the amount of amphetamine ordered from the applicant; the drugs were supplied by B. The applicant was arrested after having handed over the drugs to S. and while collecting the money from C. The police further seized 10 grams of amphetamine in the applicant’s flat and numerous guns in his garage. 13.  B., having been informed of his right to remain silent, confirmed to the police after his arrest and subsequently before the investigating judge that he had participated in the drug transaction on 16 October 2007 and supplied the amphetamine seized on that day. 14.  On 31 July 2008 the Trier Regional Court convicted the applicant of two counts of drug trafficking in not insignificant amounts while carrying a weapon and another count of drug trafficking in not insignificant amounts and sentenced him to five years and six months’ imprisonment. 15.  The Regional Court established the facts as summarized above (see paragraphs 6-13 above). It further took note of the fact that the applicant, a full member of the motorbike club “MC Bandidos Chapter Kaiserslautern”, had previously been convicted, in particular, by the Trier Regional Court of trafficking in drugs (amphetamine) on 9 February 1989 and sentenced to three years and ten months’ imprisonment. 16.  The Regional Court observed that the applicant and his co-accused B. had not made any submissions on the drug charges during the trial hearing. Its findings of fact were based on the credible statements made by S. to his supervising police officer K. and, in respect of the last offence, on the confession made by co-accused B. during the investigation proceedings. 17.  In the hearing, the Regional Court, having rejected the applicant’s objection to hearing police officer K. as a witness, had questioned K. as a witness giving hearsay evidence on the observations made by police informer S. It had not been possible to summon and question S. in person as the Rhineland-Palatinate Ministry for the Interior had issued a declaration dated 10 April 2008, supplemented on 21 July 2008 following the trial court’s proposal of alternative methods of questioning, blocking the disclosure of his identity (Sperrerklärung). These declarations, running to twelve and four pages respectively, had been read out in the hearing. 18.  The Ministry had argued in these declarations that it was necessary to keep the identities of police informer S., and also of undercover police officer C., secret in order to protect their life and limb and that of their relatives. In the Ministry’s submission, there was a high risk that the applicant would organise a violent revenge against them. He was a member of the motorbike club “MC Bandidos, Chapter Kaiserslautern”, which was well-organised worldwide and known for violent, ruthless acts against persons considered as traitors. Members of the motorbike club were currently suspected of involvement in homicides. The applicant, on whose premises a considerable number of firearms had been found, had himself offered S. EUR 1,000 for assaulting a former member of the motorbike club who was suspected of having deceived the club in the course of business transactions. Further perpetrators who had been involved in the drug deal might equally possess firearms and had not been arrested yet. The disclosure of the identity of the police informer and of the well-trained undercover agent would further compromise the police’s ability to investigate serious crimes with their help or that of other informers in the future. 19.  The Ministry further stated that there were no means other than the non-disclosure of their identity for the Land to protect the physical integrity of the police informer and of the undercover agent. In particular, keeping their names or places of residence secret or excluding the public and the applicant during their interrogation in court would be insufficient to protect them, owing to the presence of the applicant’s lawyers and possibly of contact persons of the applicant observing the court building at the day of the trial. The Ministry also rejected the Regional Court’s proposal to have S. questioned by a commissioned judge outside the main hearing as the applicant’s lawyers would be present during such a hearing and might pass on information to the applicant allowing the latter to detect S.’s identity. Likewise, a video conference including acoustic and optical shielding, as equally proposed by the Regional Court, could not exclude S.’s and C.’s identification by their figure, by their gestures and language used or by the disclosure of details permitting the detection of their identity in the course of questioning by the defence. 20.  In the Regional Court’s view, the reasons given in the Ministry’s declarations for the non-disclosure of S.’s, and also C.’s, identities were neither arbitrary nor obviously unlawful. 21.  The Regional Court noted that police officer K. had questioned S. on 26 October 2007 and had reported S.’s statements in the hearing. It had then given the defence the opportunity to put questions to S. in writing. On 25 June 2008 K. again questioned S., submitting to him the court’s questions and those of B.’s defence counsel, and again reported S.’s statements in court. Both police officer K.’s and S.’s detailed statements without contradictions were credible, having regard also to the fact that it had only hearsay evidence before it. The Regional Court noted, in particular, that the applicant had contested having carried a loaded revolver during the first two transactions, claiming that the object in his pocket had been a multi-tool. It found that S. had already mentioned on 26 October 2007 that the applicant had carried a weapon. When again being questioned by police officer K. on the court’s request on 25 June 2008, S. had given more details in respect of the revolver and had convincingly explained when and how he had seen that it had been loaded, which demonstrated the veracity of his statements. 22.  The Regional Court found that the statements made by the police informer could be used as evidence. Under the well-established case-law of the Federal Court of Justice (the Regional Court referred to Federal Court of Justice, file no. 1 StR 221/99, judgment of 18 November 1999, BGHSt 45, pp. 321 ss., see paragraph 34 below), the use of police informers was permitted to combat serious crimes which were difficult to investigate, such as drug trafficking. It was not relevant in that context whether the applicant had been incited by a police informer to commit an offence as, in any event, this would not lead to an exclusion of evidence. In that event, the court would only have to state in the reasons of its judgment that there had been a breach of the right to a fair trial under Article 6 § 1 of the Convention and would have to mitigate the penalty as a result thereof. 23.  The Regional Court considered that S.’s submissions had been supported by considerable further circumstantial evidence. In particular, the nature and amount of drugs trafficked was proven as S. had handed the drugs in question over to the police immediately after the respective transactions. Moreover, in respect of the last offence, the applicant and B. had been caught in the act and arrested at the scene of the crime. Furthermore, B. had initially confessed to the (third) offence in the investigation proceedings and his statements had been reported in the hearing by the police officer and the investigating judge who had questioned him at the time. 24.  Finally, both B.’s confession and S.’s statements concerning the second offence had been confirmed by the submissions made by undercover police officer C. to police officer L. who supervised him. L. had testified as a witness giving hearsay evidence in the hearing, the court having dismissed the applicant’s objection to hearing him. The identity of C. had remained unknown as he had equally been covered by the Ministry’s declaration blocking a disclosure of his identity. The investigations by an undercover police officer had been lawful under Articles 110a and 110b § 2 of the Code of Criminal Procedure (see paragraphs 31-32 below), as they had been authorised by the Public Prosecutor’s Office and the District Court and had been indispensable in order to further investigate suspicions of drug trafficking by the applicant. 25.  When fixing the sentence, the Regional Court considered as aggravating factors the frequency of the offences as well as the applicant’s prior conviction for drug trafficking. It took into account as mitigating elements that the drug transactions had been under police surveillance from the outset and that the drugs could not, therefore, freely circulate on the market. Moreover, the applicant had trafficked in so-called soft drugs of average quality only. Furthermore, the applicant was disabled at a rate of 70 per cent and therefore particularly susceptible to suffer from detention. 26.  In the Regional Court’s view the applicant had not, however, been unduly incited by police informer S. to commit the offences in question, within the meaning of the case-law of the Federal Court of Justice (the Regional Court again referred to the Federal Court of Justice’s judgment of 18 November 1999, cited above, BGHSt 45, pp. 321 ss.). The applicant had already been involved in drug trafficking and been predisposed to sell drugs prior to his meeting with the police informer. This was proven, in particular, by the fact that he had supplied S. with an amphetamine sample already when they discussed drug transactions for the first time. Moreover, he had indicated on that occasion that he could supply S. with larger amounts of drugs. The Regional Court found in that context that the price offered by S. to the applicant (EUR 4,000) was the average price for a kilogram of amphetamine of average quality in the region. Furthermore, the applicant had previously been convicted of drug trafficking. As his offences had not therefore been the result of unlawful police incitement, there was no ground for mitigating the sentence on that account. 27.  On 1 August 2008 the applicant lodged an appeal on points of law with the Federal Court of Justice. He claimed, in particular, that his right to a fair trial under Article 6 §§ 1 and 3 (d) of the Convention had been breached as he had been unable to cross-examine police informer S. and undercover agent C., on whose submissions his conviction had essentially been based. Moreover, S. had unduly incited him to sell drugs. The evidence obtained by the incitement should therefore have been excluded at his trial. 28.  On 12 December 2008 the Federal Court of Justice dismissed the applicant’s appeal on points of law against the Regional Court’s judgment as ill-founded. 29.  On 19 January 2009 the applicant lodged a constitutional complaint with the Federal Constitutional Court. He complained, in particular, that the judgment of the Regional Court, confirmed by the Federal Court of Justice, had breached his right to a fair trial under the Basic Law. He had been unduly incited by the prosecution authorities to commit the offences he had later been found guilty of. Therefore, the evidence obtained by police incitement should have been excluded at his trial (he referred to the European Court of Human Right’s judgment in the case of Pyrgiotakis v. Greece, no. 15100/06, 21 February 2008 to support his view). Moreover, throughout the proceedings, he had not had an opportunity to question the police informer and the undercover police officer. 30.  On 3 September 2009 the Federal Constitutional Court declined to consider the applicant’s constitutional complaint (file no. 2 BvR 164/09). The decision was served on the applicant’s counsel on 10 September 2009.