CEDH · CASELAW;JUDGMENTS;CHAMBER;ENG — 7 octobre 2025

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margin-left:51.05pt; margin-bottom:6pt; text-indent:-17.05pt; text-align:justify; page-break-inside:avoid; page-break-after:avoid; font-size:10pt } .s4B52A9A9 { margin-top:14pt; margin-left:51.05pt; margin-bottom:6pt; text-indent:-17.05pt; text-align:justify; page-break-inside:avoid; page-break-after:avoid; font-size:10pt } .s4196892D { width:3.17pt; font:7pt 'Times New Roman'; display:inline-block } .s448F0C15 { margin-top:14pt; margin-left:18pt; margin-bottom:12pt; text-indent:-18pt; text-align:justify; page-break-inside:avoid; page-break-after:avoid; font-size:14pt } .sD11CFAB7 { margin-top:14pt; margin-left:15.01pt; margin-bottom:3pt; text-align:justify; padding-left:1.99pt; font-family:Arial } .sFBC99493 { font-style:italic } .s69DCC830 { margin-top:36pt; margin-bottom:0pt } .sC986E16F { font-family:Arial; color:#ffffff } .s95770030 { margin-top:30pt; margin-bottom:0pt } .sC2E086EB { width:36.89pt; display:inline-block } .s829C9466 { width:149.43pt; display:inline-block } .s5A65B3DC { width:46.56pt; display:inline-block } .s44B8752F { width:177.11pt; display:inline-block } .s2D726B78 { margin-top:0pt; margin-bottom:12pt; text-align:center; page-break-inside:avoid; page-break-after:avoid } .s7ED160F0 { text-decoration:none } .s33165EBA { font-family:Arial; font-size:8pt; vertical-align:super; color:#0069d6 } .sF6A12959 { width:33%; height:1px; text-align:left } .s85226119 { margin-top:0pt; margin-bottom:0pt; text-align:justify; font-size:10pt } .s653E6C45 { font-family:Arial; font-size:6.67pt; vertical-align:super; color:#0069d6 } THIRD SECTION CASE OF HELME v. ESTONIA (Application no. 3023/22)   JUDGMENT   Art 6 (criminal) • Fair hearing • Conviction of applicant following explicitly sexual conversations with an undercover police officer purporting to be a 12-year-old girl in an online chatroom, and the use of the resulting evidence in the criminal proceedings against him • Alleged entrapment in an online context • Existence of good reasons for initiating undercover operation on the basis of information received on potential sexual enticement of minors on the relevant website • Feasibility of prior identification of possible suspects in online context prior to mounting an undercover operation • Lack of objective suspicion that it was the applicant specifically who had been involved in criminal activity or was predisposed to engage in such conduct not decisive • Existence of an objective suspicion that was specific to a defined and limited virtual space • Context of crimes against minors • Initiation of undercover operation did not imply an intention to entrap the applicant • Actions of the police did not constitute as such unlawful activity nor did they presume illegal actions on the part of the person they were communicating with • Undercover police officer did not abandon required passive attitude • Applicant not under any express or implied pressure to commit the impugned offence • Use of undercover police officer did not amount to incitement   Prepared by the Registry. Does not bind the Court.   STRASBOURG 7 October 2025   FINAL   09/02/2026   This judgment has become final under Article 44 § 2 of the Convention. It may be subject to editorial revision. In the case of Helme v. Estonia, The European Court of Human Rights (Third Section), sitting as a Chamber composed of:   Ioannis Ktistakis , President ,   Peeter Roosma,   Lətif Hüseynov,   Darian Pavli,   Diana Kovatcheva,   Canòlic Mingorance Cairat,   Vasilka Sancin , judges , and Milan Blaško, Section Registrar, Having regard to: the application (no.   3023/22) against the Republic of Estonia lodged with the Court under Article 34 of the Convention for the Protection of Human Rights and Fundamental Freedoms (“the Convention”) by an Estonian national, Mr Peeter Helme (“the applicant”), on 10 January 2022; the decision to give notice to the Estonian Government (“the Government”) of the complaint under Article 6 § 1 of online entrapment, and to declare the remainder of the application inadmissible; the parties’ observations; Having deliberated in private on 9 September 2025, Delivers the following judgment, which was adopted on that date: INTRODUCTION 1.     The application concerns the applicant’s alleged online entrapment by an undercover police officer who, while using a pseudonym, engaged in conversations with the applicant in an online chatroom. The applicant complained that evidence resulting from that police operation had been used in criminal proceedings against him, in breach of his right to a fair trial. THE FACTS 2.     The applicant was born in 1978 and lives in Tallinn. He was represented by Mr R. Ainla, a lawyer practising in Tallinn. 3.     The Government were represented by their Agent, Mr T. Kolk, Representative of Estonia to the European Court of Human Rights. 4.     The facts of the case may be summarised as follows. Authorisation and use of an undercover police officer 5.     On 19 September 2019 criminal proceedings were initiated on the basis of information received earlier that year indicating that various persons had used certain internet sites (www.facebook.com and www.armastusesaal.org) to engage in chats of a sexual nature with minors under the age of 14 and had sent them files containing sexual content. No additional information has been provided regarding the nature or source(s) of the above-mentioned information. 6.     On the basis of the information described in the previous paragraph, on 27   September 2019, under Article 126 9 of the Code of Criminal Procedure ( kriminaalmenetluse seadustik ), the prosecutor’s office authorised the use of an undercover police officer to gather information on the website www.armastusesaal.org (which translates as “hall of love”). 7.     Between 8 October 2019 and 8 December 2019 the police conducted a secret surveillance operation on that website. A police officer using the fictional identity of a 12-year-old girl named Marleen Ilus and the pseudonym “Marleen12” used online chatrooms on that site in order to collect information relevant to the proceedings. 8.     During that operation a person with the username “m41tln” had explicitly sexual conversations via private messages with “Marleen12” on the website. 9.     On the basis of the information obtained from the above-mentioned conversations, on 17 November 2019 separate criminal proceedings were initiated to investigate the possible commission of an offence by the person using the username “m41tln”. The proceedings revealed that the applicant was the person behind that username. The transcripts of those conversations were included in a report on the secret surveillance operation. That report was subsequently used as evidence in the proceedings against the applicant. 10 .     The transcripts show that the applicant initiated chats with “Marleen12” on 8   October 2019 at 7.52 p.m., 9 October 2019 at 5.58 p.m., 14   October 2019 at 5.46 p.m., 3 November 2019 at 1.46 p.m., 10 November 2019 at 5.46   p.m., 11   November at 4.35 p.m., 17 November 2019 at 11.00 a.m., 22   November 2019 at 7.16 p.m., 30 November 2019 at 3.37 p.m., 1 December 2019 at 6.20   p.m., 4   December 2019 at 3.49 p.m. and 8 December 2019 at 6.12 p.m. During the chat on 8   October 2019, at 7.58   p.m. “Marleen12” stated that she was 12 years old. On a couple of occasions when “Marleen12” did not respond immediately, the applicant repeated his greetings. During those chats, the applicant brought up sex-related topics on numerous occasions. For example, on 9   October 2019 he noted that chats in the chatroom usually covered topics involving sex and asked “Marleen12” to give examples of issues she had seen being discussed. He followed this up by asking whether she already had “boobs” and whether she had heard that some people had sex with very young children. On 3   November 2019 he mentioned that he had visited a woman who had a very young daughter – younger than “Marleen12” – and that he had had sex with that girl, and he followed this up by asking whether “Marleen12” was interested in sex. On 17   November 2019 he asked “Marleen12” to remind him whether she had already had sex, whether she had watched porn, masturbated and had an orgasm, and whether she was sexually interested in girls or women. Court proceedings against the applicant 11.     On 30 November 2020 the Harju County Court convicted the applicant of attempted sexual enticement of a minor. 12.     In response to a request by the applicant, the Harju County Court analysed the lawfulness of the above-described secret surveillance operation with a view to determining whether the report on that operation, which contained transcripts of the applicant’s chats, could be admitted in evidence. 13 .     The court familiarised itself with the secret surveillance file. It confirmed that the use of an undercover police officer had been authorised by the prosecutor’s office. The authorisation had concerned an offence in respect of which secret surveillance operations could be conducted under the Code of Criminal Procedure. Referring to two authorisation decisions in the file, the court considered that at the time of authorising the use of an undercover police officer, there had been a reasonable suspicion that an offence had been committed. The authorisation decisions had contained relevant reasoning and the principle of ultima ratio had been followed. Given the hidden nature of the crime under investigation, and as it had concerned an offence targeting minors, it had been justified and proportionate to use an undercover police officer. Such offences were often committed in a manner that made their discovery complicated, and offenders were likely to try to eliminate any kind of evidence of the offences. 14 .     The court concluded that the use of an undercover police officer had been lawful, and that the evidence thereby obtained was admissible. 15.     As to the substance of the conversations between the applicant and “Marleen12”, after examining the content of the chats, the court found that the police officer had not incited the applicant in any manner. The applicant had initiated the conversations and he had taken all the initiative in maintaining them. 16 .     Thereafter, on the basis of the manner in which the website in question operated, the pseudonym that the undercover officer had used and the content of the chats between the applicant and the police officer, the Harju County Court found that the applicant must indeed have thought that he was chatting to a 12-year-old girl. The court noted that the applicant, as a frequent user of the website, must have been aware that the site did not require confirmation that the person accessing it was an adult. The witnesses (who maintained the server and the website) also confirmed at the court hearing that the portal was not intended only for adults. The court also noted that the applicant had used his own age in his username and thus should have assumed that the other person had done the same. Therefore, the court did not find plausible the applicant’s claims that in his opinion he had been playing a role-playing game and had believed that the person behind the computer had not been an underaged girl, but an adult with similar role-play interests. On the basis of the content of the conversations, the court found that the applicant had tried to arouse the interest of the undercover police officer, whom he had believed was a 12-year-old girl named Marleen, in topics of a sexual nature. 17 .     The applicant appealed. He argued that there had been no prior information about his possible criminal behaviour. He noted that the criminal proceedings against him had been initiated only after the police officer had incited him to commit an offence. He concluded that the secret surveillance authorisations had been issued not to target him specifically, but to incite “sexual enticers of [children] under 14 years old” to commit offences. The police had entered the chatroom with a specific purpose – to lure those who took an interest in children under 14 years old into conversation. The username “Marleen12” had been chosen deliberately to provoke people to have a conversation. 18.     On 10 June 2021 the Tallinn Court of Appeal dismissed the appeal and upheld the first-instance judgment. 19.     The Tallinn Court of Appeal agreed with the reasoning of the Harju County Court that the extracts of the conversations between the applicant and the undercover police officer did not indicate that the officer using the username “Marleen12” had in any way provoked the applicant to talk about sexual topics. The court found that it was clear from the extracts that the applicant was the one who had always initiated the conversations about sexual topics and that when the police officer posing as “Marleen12” had remained passive, the applicant had urged her to talk and ask about sex and express her sexual desires, and the undercover police officer had mostly given short answers in response. 20.     The Court of Appeal found that the use of the police officer had not been aimed at inciting the applicant to commit a criminal offence, but verifying information received by the police indicating that various persons had used certain websites to engage in chats of a sexual nature with minors under the age of 14 and had sent them files containing sexual content. To that end, criminal proceedings under Article 179 § 1 of the Criminal Code had been initiated. 21 .     The applicant lodged an appeal on points of law. He repeated his arguments about having been incited to commit an offence (see paragraph   17 above). He added that the fact that he had initiated the conversations about sex-related topics and that the police officer had remained passive in those chats was irrelevant, as it was in any event illogical, in the context of enticement, that the minor himself or herself would have started conversations on sexual topics. The incitement stemmed from the fact that the police officer had assumed the role of a minor and had chosen a username which had led him to believe that it was a minor who was engaging in the chat. 22.     On 17 August 2021 the Supreme Court decided not to examine the applicant’s appeal on points of law and his conviction became final. RELEVANT LEGAL FRAMEWORK AND PRACTICE Relevant domestic law 23 .     Article 179 § 1 of the Criminal Code provides that handing over, displaying or knowingly making pornographic works or reproductions thereof available in some other way to a person under the age of 14, or showing sexual abuse to such a person, engaging in sexual intercourse in the presence of such a person or knowingly sexually enticing such a person in any other manner, is punishable by a fine or up to three years’ imprisonment. 24.     Article 126 9 § 1 of the Code of Criminal Procedure provides that the term “undercover agent” means a person who uses a different identity to collect information for the reasons mentioned in Article 126 2 §§ 1 (1), (3) or (4) of the Code of Criminal Procedure. 25.     In so far as is relevant, Article 126 2 §§ 1 (1) and (4) of the Code of Criminal Procedure provide that the Police and Border Guard Board may conduct a secret surveillance operation for the following reasons: if there is a need to collect information about the preparation of a criminal offence, for the purpose of detecting or preventing that offence; or if there is a need to collect information about a criminal offence, in the context of criminal proceedings. 26.     Article 126 2 § 2 provides that a secret surveillance operation can be conducted for the reasons mentioned in Article 126 2 §§ 1 (1) and (4), provided that the case concerns a criminal offence mentioned in, among other things, Article 179 of the Criminal Code. 27.     Article 126 9 § 2 of the Code of Criminal Procedure adds that authorisation to use an undercover agent must be granted by the prosecutor’s office in writing. The authorisation is granted for up to six months and the time-limit in question may be extended by up to six months at a time. Relevant domestic case-law 28.     In judgment no. 3-1-1-110-04 of 2 December 2004, the Supreme Court explained that several offences required the person simulating an offence (the agent provocateur ) to be the more active party in initiating contact (for example, in the case of buying narcotic drugs), and that his or her actions could not be limited to mere passive investigation. However, it was understandable that the actions of the person simulating an offence could not be unlimited and without legal restrictions. For example, it was impermissible to incite a person to commit an offence in circumstances where that person had absolutely no prior intention to do so and the investigating authorities had no prior information about his or her possible criminal behaviour. In order to assess whether the incitement to commit an offence was permissible or not, criteria such as the basis of the initial suspicion against the accused (for example, the credibility of the source) and the seriousness of the offence (for example, whether the offence was a minor offence or a serious criminal offence) had to be taken into account, as well as how and how much the agent provocateur influenced the person in question (for example, luring him or her with large sums of money or threatening him or her, or outlining courses of action which he or she could choose to take). It was also necessary to take into account that person’s own readiness to act and the actions which he or she carried out of his or her own accord – in other words, the extent of his or her individual participation (whether he or she performed certain tasks without the leadership and initiation of the agent provocateur , and so on). In doing so, it was important to note that these were not individual and independent evaluation criteria, and all the above-mentioned circumstances had to be weighed up as part of an overall assessment. 29.     The above reasoning was repeated and referred to in judgment no.   1-16-1036 of 1 December 2017 of the Supreme Court. Relevant international material 30 .     The Council of Europe Convention on the Protection of Children against Sexual Exploitation and Sexual Abuse (“the Lanzarote Convention”) entered into force on 1 July 2010, was ratified by Estonia on 11 November 2016 and entered into force with respect to Estonia on 1 March 2017. It lists various forms of “sexual exploitation and sexual abuse of children”, compelling each Party to that Convention to take necessary legislative or other measures to ensure the criminalisation of such exploitation and abuse. One of those acts – solicitation of children for sexual purposes – is listed in Article 23 of that Convention, which provides as follows: Article 23 – Solicitation of children for sexual purposes “Each Party shall take the necessary legislative or other measures to criminalise the intentional proposal, through information and communication technologies, of an adult to meet a child who has not reached the age set in application of Article 18, paragraph   2, for the purpose of committing any of the offences established in accordance with Article 18, paragraph 1.a, or Article 20, paragraph 1.a, against him or her, where this proposal has been followed by material acts leading to such a meeting.” 31 .     The relevant parts of the Explanatory Report to the Lanzarote Convention provide as follows: Article 23 – Solicitation of children for sexual purposes “155. Article 23 introduces a new offence in the Convention which is not present in other existing international instruments in the field. The solicitation of children for sexual purposes is more commonly known as ‘grooming’. The negotiators felt it was essential for the Convention to reflect the recent but increasingly worrying phenomenon of children being sexually harmed in meetings with adults whom they had initially encountered in cyberspace, specifically in Internet chat rooms or game sites. 156. The term ‘grooming’ refers to the preparation of a child for sexual abuse, motivated by the desire to use the child for sexual gratification. It may involve the befriending of a child, often through the adult pretending to be another young person, drawing the child into discussing intimate matters, and gradually exposing the child to sexually explicit materials in order to reduce resistance or inhibitions about sex. The child may also be drawn into producing child pornography by sending compromising personal photos using a digital camera, web-cam or phone-cam, which provides the groomer with a means of controlling the child through threats. Where a physical meeting is arranged the child may be sexually abused or otherwise harmed. 157. The negotiators felt that simply sexual chatting with a child, albeit as part of the preparation of the child for sexual abuse, was insufficient in itself to incur criminal responsibility. A further element was needed. Article 23, therefore, requires Parties to criminalise the intentional ‘proposal of an adult to meet a child who has not reached the age set in application of Article 18 paragraph 2’ for the purpose of committing any of the offences established in accordance with Article 18 paragraph 1 a or Article   20 paragraph 1 a against him or her. Thus the relationship-forming contacts must be followed by a proposal to meet the child. 158. All the elements of the offence must be committed intentionally. In addition, the ‘purpose’ of the proposal to meet the child for committing any of the specified offences needs to be established before criminal responsibility is incurred. 159. The offence can only be committed ‘through the use of information and communication technologies’. Other forms of grooming through real contacts or non-electronic communications are outside the scope of the provision. In view of the particular danger inherent in the use of such technologies due to the difficulty of monitoring them the negotiators wished to focus the provision exclusively on the most dangerous method of grooming children which is through the Internet and by using mobile phones to which even very young children increasingly now have access. 160. In addition to the elements specified above the offence is only complete if the proposal to meet ‘has been followed by material acts leading to such a meeting’. This requires concrete actions, such as, for example, the fact of the perpetrator arriving at the meeting place.” THE LAW ALLEGED VIOLATION OF ARTICLE 6 § 1 OF THE CONVENTION 32.     The applicant complained that he, a person who had had no criminal record prior to the secret surveillance operation, had been unlawfully entrapped online in violation of Article 6 § 1 of the Convention, which reads as follows: “In the determination of ... any criminal charge against him, everyone is entitled to a fair ... hearing ... by [a] ... tribunal ...” Admissibility 33.     The Government, relying on the same reasons as those advanced as regards the merits of the case, argued that the complaint was manifestly ill-founded. 34 .     The applicant disagreed. 35.     The Court notes that this complaint is neither manifestly ill-founded nor inadmissible on any other grounds listed in Article   35 of the Convention. It must therefore be declared admissible. Merits The parties’ observations (a)    The applicant 36.     The applicant asserted that the criminal investigation had been initiated on the basis of general information and without any specific knowledge of any identified individuals who were having chats with minors. Thus, the criminal investigation had been initiated with the clear aim of inciting people and collecting information on persons who might entice children under 14 years old. 37 .     The applicant stated that prior to the secret surveillance operation in question he had not had any criminal record and had not been suspected of any offence. He stated that the pseudonym “Marleen12” used by the undercover police officer – which clearly suggested that the person using that name was a minor – had obviously been chosen to incite him. 38.     The criminal proceedings against him had been initiated only after such incitement. 39 .     The applicant did not submit any observations on how the conversations with the police officer using the name “Marleen12” had been conducted. (b)    The Government 40.     The Government argued that the facts of the case revealed no issues as regards fairness, equality of arms or the adversarial nature of the proceedings against the applicant, or as regards manifest and flagrant arbitrariness in those proceedings. The Government addressed both the substantive and procedural tests for incitement. 41.     The Government noted that two sets of criminal proceedings were relevant in the context of the present case. Initially, on 19   September 2019 criminal proceedings had been initiated on the basis of information received by the police earlier that year indicating that various persons had used certain websites to engage in chats of a sexual nature with minors under the age of 14 and had sent them files containing sexual content. Next, in the course of those proceedings, a secret surveillance operation authorised under Article   126 9 of the Code of Criminal Procedure had been conducted from 8   October 2019 to 8 December 2019. The Government agreed that the police officer had first entered the chatroom in question with no prior knowledge of or suspicions regarding the applicant. 42 .     During the operation, a person using the username “m41tln” had sexually enticed a fictional 12-year-old girl called Marleen (who had actually been an undercover officer using the pseudonym “Marleen12”) via private messages sent on that website. On the basis of that information, separate criminal proceedings had been initiated on 17 November 2019. The object of those proceedings had been to find out whether the person using the username “m41tln” had committed the criminal offence of sexual enticement of a minor. That person had turned out to be the applicant. Thus, the applicant’s own behaviour had given rise to a concrete suspicion against him and the criminal proceedings against him had been initiated on the basis of the actions he had carried out while using the username “m41tln”. 43.     As to the use of the undercover officer, the Government argued that such a course of action had been justified and proportionate, given the hidden nature of the offence in question and the fact that it had been taking place online. The applicant had been able to question the existence and lawfulness of the authorisation to carry out that secret surveillance operation, and to challenge the admission in evidence of the transcripts resulting from the operation. The Harju County Court had addressed the applicant’s arguments after familiarising itself with the secret surveillance file. 44.     The Government emphasised that the applicant had not questioned the Harju County Court’s conclusions about the lawfulness of the authorisation and the use of the police officer in his subsequent appeals. In the Government’s opinion, the applicant could not therefore complain of the unlawfulness of the secret surveillance operation or about the police officer’s presence in the chatroom in the proceedings at hand. Thus, the issue of whether there had been impermissible incitement could be assessed only with reference to the content of the applicant’s conversation with the police officer in the chatroom. 45.     The Government further noted that the applicant had been able to challenge the assessment of the transcripts of the chats and to put forward his own interpretation of them, including by raising arguments about improper incitement. The domestic courts had given due consideration to his arguments. There was no reason to depart from their well-reasoned assessment. 46.     According to the Government, there was nothing in the present case to indicate that the applicant had been incited to commit a criminal offence. It was evident from the extracts of the conversations between him and the police officer that the officer had not incited him in any way. It had been the applicant alone who had initiated the conversations and brought up inappropriate topics, including urging “Marleen12” to ask about sex and express her sexual desires. The police had not exceeded the boundaries of essentially passive investigation. The Court’s assessment (a)    General principles (i)       Overall approach regarding undercover agents 47 .     The Court is aware of the difficulties inherent in the police’s task of searching for and gathering evidence for the purpose of detecting and investigating offences. To perform this task, they are increasingly required to make use of undercover agents, informers and covert practices, particularly in tackling organised crime and corruption. Accordingly, the use of special investigative methods – in particular, undercover techniques – cannot in itself infringe the right to a fair trial. However, on account of the risk of police incitement entailed by such techniques, their use must be kept within clear limits (see Ramanauskas v. Lithuania [GC], no. 74420/01, §§   49-51, ECHR 2008). 48.     In this connection, it should be reiterated that it is the Court’s task, in accordance with Article 19, to ensure the observance of the engagements undertaken by the States Parties to the Convention. The admissibility of evidence is primarily a matter for regulation by national law and, as a rule, it is for the national courts to assess the evidence before them. The Court, for its part, must ascertain whether the proceedings as a whole, including the way in which evidence was taken, were fair. In this context, the Court’s task is not to determine whether certain items of evidence were obtained unlawfully, but rather to examine whether such “unlawfulness” resulted in the infringement of another right protected by the Convention (ibid., §   52, with further references). 49.     More particularly, the Convention does not preclude reliance, at the preliminary investigation stage and where the nature of the offence may warrant it, on sources such as anonymous informants. However, the subsequent use of such sources by the trial court to found a conviction is a different matter and is acceptable only if adequate and sufficient safeguards against abuse are in place, in particular a clear and foreseeable procedure for authorising, implementing and supervising the investigative measures in question (ibid., §   53; see also Khudobin v. Russia , no. 59696/00, §   135, ECHR 2006-XII). 50.     Furthermore, while the use of undercover agents may be tolerated provided that it is subject to clear restrictions and safeguards, the public interest cannot justify the use of evidence obtained as a result of police incitement, as to do so would expose the accused to the risk of being definitively deprived of a fair trial from the outset (see, among other authorities, Ramanauskas , cited above, §   54; see also Teixeira de Castro v.   Portugal , 9 June 1998, §§   35-36, Reports of Judgments and Decisions 1998 ‑ IV; Khudobin , cited above, §   128; and Vanyan v.   Russia , no.   53203/99, §§   46 ‑ 47, 15   December 2005). 51.     Police incitement occurs where the officers involved – whether members of the security forces or persons acting on their instructions – do not confine themselves to investigating criminal activity in an essentially passive manner, but exert such an influence on the subject as to incite the commission of an offence that would otherwise not have been committed, in order to make it possible to establish the offence, that is, to provide evidence and institute a prosecution (see Ramanauskas , cited above, §   55, and Teixeira de Castro , cited above, §   38). 52.     In its extensive case-law on the subject the Court has developed criteria to distinguish entrapment breaching Article 6 §   1 of the Convention from permissible conduct in the use of legitimate undercover techniques in criminal investigations. Whereas it is not possible to reduce the variety of situations which might occur in this context to a mere checklist of simplified criteria, the Court’s examination of complaints of entrapment has developed on the basis of two tests: the substantive and the procedural test of incitement. The relevant criteria determining the Court’s examination in this context are set out in the case of Bannikova v. Russia (no.   18757/06, §§   37-65, 4   November 2010). These criteria are summarised below (see Matanović v.   Croatia , no. 2742/12, §§   122-35, 4   April 2017). (ii)     Substantive and procedural tests of incitement 53.     When examining the applicant’s arguable plea of entrapment, the Court will attempt, as a first step, to establish on the basis of the available material whether the offence would have been committed without the authorities’ intervention, that is to say whether the investigation was “essentially passive”. In deciding whether the investigation was “essentially passive” the Court will examine the reasons underlying the covert operation, in particular, whether there were objective suspicions that the applicant had been involved in criminal activity or had been predisposed to commit a criminal offence (see Furcht v. Germany , no. 54648/09, §   51, 23   October 2014) and the conduct of the authorities carrying it out, specifically whether the authorities exerted such an influence on the applicant as to incite the commission of an offence that would otherwise not have been committed, in order to make it possible to establish the offence, that is, to provide evidence and institute a prosecution (ibid., §   52; see also Morari v. the Republic of Moldova , no. 65311/09, §   32, 8 March 2016). 54.     In this connection, the Court has also emphasised the need for a clear and foreseeable procedure for authorising investigative measures, as well as for their proper supervision. It has considered judicial supervision to be the most appropriate means in cases involving covert operations, although with adequate procedures and safeguards, other means may be used, such as supervision by a prosecutor (see Furcht , cited above, § 53; see also Bannikova , cited above, §§ 49-50, with further references). Indeed, a lack of procedural safeguards in the ordering of an undercover operation generates a risk of arbitrariness and police entrapment (see Nosko and Nefedov v.   Russia , nos.   5753/09 and 11789/10, § 64, 30   October 2014). 55.     As a second step, the Court will examine the way the domestic courts dealt with the applicant’s plea of incitement, which is the procedural part of its examination of the agent provocateur complaint (see Bannikova , cited above, §§   51-65, with further references). 56.     As the starting point, the Court must be satisfied with the domestic courts’ capacity to deal with such a complaint in a manner compatible with the right to a fair hearing. It should therefore verify whether an arguable complaint of incitement constitutes a substantive defence under domestic law, or gives grounds for the exclusion of evidence, or leads to similar consequences. Although the Court will generally leave it to the domestic authorities to decide what procedure must be followed by the judiciary when faced with a plea of incitement, it requires such a procedure to be adversarial, thorough, comprehensive and conclusive on the issue of entrapment. 57.     In particular, the questions to be addressed by the judicial authority when deciding on an entrapment plea were set out in Ramanauskas , cited above, §   71: “The Court observes that throughout the proceedings the applicant maintained that he had been incited to commit the offence. Accordingly, the domestic authorities and courts should at the very least have undertaken a thorough examination ... of whether or not [the prosecuting authorities] had incited the commission of a criminal act. To that end, they should have established in particular the reasons why the operation had been mounted, the extent of the police’s involvement in the offence and the nature of any incitement or pressure to which the applicant had been subjected. ... The applicant should have had the opportunity to state his case on each of these points.” 58.     Moreover, the principles of adversarial proceedings and equality of arms are indispensable in the determination of an agent provocateur claim, as well as the procedural guarantees related to the disclosure of evidence and questioning of the undercover agents and other witnesses who could testify on the issue of incitement ( Bannikova , cited above, §§ 58 and 65). 59.     In this connection, the Court also reiterates that it falls to the prosecution to prove that there was no incitement, provided that the defendant’s allegations are not wholly improbable. In practice, the authorities may be prevented from discharging this burden by the absence of formal authorisation and supervision of the undercover operation (ibid., §   48). (iii)    Application of the substantive and procedural tests of incitement 60 .     It follows from the Court’s case-law that a preliminary consideration in its assessment of a complaint of incitement relates to the existence of an arguable complaint that an applicant was subjected to incitement by the State authorities. In this connection, in order to proceed with further assessment, the Court must satisfy itself that the situation under examination falls prima facie within the category of “entrapment cases” (see, for cases where this criterion was not met, Trifontsov v. Russia (dec.), no.   12025/02, §§   32-35, 9   October 2012; Lyubchenko v. Ukraine (dec.), no.   34640/05, §§   33-34, 31   May 2016; and Matanović v. Croatia , no. 2742/12, §   131, 4   April 2017). 61.     If the Court is satisfied that the applicant’s complaint falls to be examined within the category of “entrapment cases”, it will proceed, as a first step, with the assessment under the substantive test of incitement (ibid., §   132). 62.     Where, under the substantive test of incitement, on the basis of the available information the Court could find with a sufficient degree of certainty that the domestic authorities investigated the applicant’s activities in an essentially passive manner and did not incite him or her to commit an offence, that will normally be sufficient for the Court to conclude that the subsequent use in the criminal proceedings against the applicant of the evidence obtained by the undercover measure does not raise an issue under Article 6 §   1 of the Convention (see, for instance, Scholer v. Germany , no.   14212/10, §   90, 18 December 2014, and Rymanov v. Russia (dec.), no.   18471/03, 13 December 2016). 63.     However, if the Court’s findings under the substantive test are inconclusive owing to a lack of information in the file, the lack of disclosure or contradictions in the parties’ interpretations of events (see Bannikova , cited above, §§   52 and 67) or if the Court finds, on the basis of the substantive test, that an applicant was subjected to incitement, contrary to Article 6 §   1, it will be necessary for the Court to proceed, as a second step, with the procedural test of incitement (see Matanović , cited above, §   134). 64 .     The Court applies this test in order to determine whether the necessary steps to uncover the circumstances of an arguable plea of incitement were taken by the domestic courts and whether in the case of a finding that there has been incitement or in a case in which the prosecution failed to prove that there was no incitement, the relevant inferences were drawn in accordance with the Convention (see Ramanauskas , cited above, §   70; Furcht , cited above, §   53; and Ciprian Vlăduț and Ioan Florin Pop v. Romania , nos.   43490/07 and 44304/07, §   88, 16 July 2015; see also Bannikova , cited above, §§   53-57, concerning the relevant inferences to be drawn from a successful plea of incitement). The proceedings against an applicant would be deprived of the fairness required by Article 6 of the Convention if the actions of the State authorities had the effect of inciting the applicant to commit the offence for which he or she was convicted and the domestic courts did not address appropriately the allegations of incitement (see Ramanauskas , cited above, §   73; Constantin and Stoian v. Romania , nos. 23782/06 and 46629/06, §   64, 29   September 2009; and Sepil v.   Turkey , no. 17711/07, §   36, 12   November 2013). (b)    Application of the general principles to the present case (i)       Preliminary remarks 65.     The Court notes that there is no dispute between the parties that the applicant, using the pseudonym “m41tln”, had explicitly sexual conversations via private messages with an undercover police officer using the username “Marleen12” on the website www.armastusesaal.org. He was subsequently convicted for this under Article 179 § 1 of the Criminal Code. The disagreement between the parties relates to whether the applicant was entrapped by the police. 66.     Based on the criteria set out in its case-law and using the methodology for the examination of complaints of entrapment (see paragraphs   60-64 above) the Court considers that the case, in view of its factual circumstances, falls within the category of “entrapment cases”. 67 .     The Court observes that the present case is the first one where it has been called upon to decide whether an individual was entrapped in a purely online context. 68.     While the factual setting of Eurofinacom v. France ((dec.), no.   58753/00, ECHR 2004-VII (extracts)) also entailed an element of online communication and police officers acting under assumed identities, the suspect in that case – and the subsequent applicant in the application lodged with the Court – was not a person offering prostitution-related services online, but rather a company which was suspected to have acted as an “intermediary between a prostitute and the person using his or her services”. More notably, in that case the Court established that the domestic police had already been in possession of information suggesting that the applicant company had been involved in unlawful activity because it had offered a communication platform. 69.     The principal issue to be examined by the Court in