September 08, 2026
By Basil Saen
As reported earlier on this blog, the European Court of Human Rights (ECtHR or the Court) issued an interesting Grand Chamber judgment in Yasak v. Türkiye on 5 May 2026. This case sits in the context of mass prosecutions and convictions of alleged members of the ‘Fetullahist Terrorist Organisation/Parallel State Structure’ (the FETÖ/PDY), designated an armed terrorist group by the Turkish authorities for its role in the attempted coup of July 2016.
To summarize the facts, Yasak was convicted in Turkey of seven years and six months’ imprisonment for membership of an armed terrorist group. Relying on witness statements, mobile phone records, social security contributions, and banking transactions, the Turkish courts found that Yasak had acted as a student leader in an education network linked to the FETÖ/PDY, which is alleged to broaden its support base by recruiting students.
The Court found violations of Article 3 and Article 7. This post focuses on Article 7, which protects the principle of legality and was violated because the Turkish courts failed to assess the applicant’s mens rea in a detailed and individualised manner. That assessment builds on earlier cases, including Yalçınkaya, Demirhan, Karslı, Bozyokuş, and Seyhan, in which the Court found similar violations following convictions for terrorist group membership based mainly on the use of ByLock, a secure messaging application linked by the Turkish authorities to the FETÖ/PDY.
This post examines what Yasak means for the role mens rea plays within the Convention system. Distinguishing a substantive and procedural dimension of mens rea, it focuses on the latter and explores how variable standards of review might reconcile different views on how the Court may apply this principle in practice.
Individual guilt is one of the foundations of criminal law. Every person is responsible for their own conduct, not for the conduct of others. This takes form in the concept of individual criminal liability, which is fundamental in many domestic systems as well as in international criminal law. It means that the conviction of each individual person must be based on evidence establishing all the constitutive elements of a charged offence, including the mental element, or mens rea: the guilty mind. Mens rea and international criminal liability are thus primarily criminal law concepts, for which the Court has subsequently set certain human rights requirements.
Mens rea, as interpreted by the Court, may be considered as having both a substantive and a procedural dimension. Substantively, the Court sets requirements for mens rea as a constitutive element of crime, adopting a minimum threshold that must be met by domestic law. Procedurally, in line with the principle of individual criminal liability, the Court confirms that criminal law judges must pay sufficient attention to mens rea and carefully assess its substantive content.
In terms of substance, Yasak does not add any new requirements. The Court merely requires that ‘a mental link (mens rea)’ must exist before punishment can be imposed (para 193). This echoes an older strand of Italian cases concerning the confiscation of unlawfully developed land (in particular Sud Fondi and G.I.E.M.), in which the Court required a ‘lien de nature intellectuelle’ or ‘mental link’. Yet, in both the Italian cases and Yasak, the Court expressly accepts strict or objective criminal liability (see, for example, G.I.E.M., para 243 and Yasak, para 193). It clarifies that this means that presumptions of liability are not prohibited, if they are rebuttable. The substantive mens rea threshold adopted by the Court is therefore low. An illustration of what meets this standard may be found in the recently reformed Belgian criminal code, where, for some offences, negligence or intent need not be demonstrated. It suffices that an accused acts consciously and of free will, a presumption that may be rebutted. Such a minimum criminal law mens rea standard complies with the Court’s substantive requirements.
Instead, the requirements set in the Turkish cases culminating in Yasak are procedural in nature. The Court does not take issue with the mens rea standard set by Turkish law, but with how the domestic courts applied it (para 204). The Court requires, emphasizing the principle of individual criminal responsibility, that all constitutive elements of the offence be assessed in a sufficiently detailed and individualised manner (paras 211-212):
‘211. […] The relevant section of the first-instance court’s judgment […] shows that it merely listed the items of evidence and proceeded to draw the conclusion that the applicant had the requisite mens rea, without seeking to explain in what way this evidence established that the applicant had been aware of the organisation’s terrorist objectives and had joined it, or continued to adhere to it, with that knowledge.
212. This failure by the domestic courts to conduct any assessment of the applicant’s mens rea in the light of the specific evidence regarding his actions and role amounted to a fundamental breach of the requirement to conduct an individualised assessment of criminal liability.’
This is noteworthy. The Turkish criminal courts had based their conviction on a broader range of evidence than in earlier cases such as Yalçınkaya. The conviction was not solely grounded on the use of ByLock, but also on witness statements, mobile phone records, social security contributions, and banking activities (para 70). The Court nevertheless found a violation of Article 7, because mens rea had still been inferred in a general manner without being explicitly tied to the available evidence in a detailed and individualised way. This sets a higher bar for domestic criminal courts compared to the Court’s earlier case law.
The sharpening of mens rea requirements may raise questions on the principle of subsidiarity and its narrower formulation, the fourth-instance doctrine. By setting substantive requirements for mens rea, the Court may tread on the domestic legislature’s territory and, by controlling the assessment of criminal courts, it comes close to acting as an appellate criminal court. These subsidiarity concerns are taken seriously by the judges dissenting from Yasak and come most clearly to the fore in Judge Ní Raifeartaigh’s separate dissenting opinion.
Judge Ní Raifeartaigh touches on subsidiarity concerns regarding both the substantive and procedural dimensions of mens rea. In terms of substance, she questions whether mens rea has obtained an autonomous Convention basis in Yasak and whether this marks a shift toward the Court shaping the content of substantive criminal law (Dissenting opinion, para 22):
‘[…] [A]t a deeper theoretical level, and ultimately of profound significance for the Convention system with regard to domestic criminal justice system, is whether the Court, in making this bold statement about a self-standing requirement of mens rea, has taken an important step away from interpreting the Convention as containing merely procedural guarantees in criminal trials, towards a new role in shaping the outlines of domestic substantive criminal law.’
However, as described above, even though the procedural requirements are sharpened in Yasak, this does not yet appear to be the case for the substantive dimension of mens rea. The Turkish offence of membership of an armed terrorist group requires the accused to act ‘knowingly and willingly’. The Court is content with that standard and recognizes that it ‘constitutes an essential guarantee in the areas of legal certainty and the protection of fundamental rights’ (para 203).
The subsidiarity concerns raised by Yasak thus appear less pressing for the substantive dimension of mens rea than for its procedural implications, which are also addressed by Judge Ní Raifeartaigh (Dissenting Opinion, para 3):
‘The Court’s commendable reluctance to become a ‘court of fourth instance’ has undoubtedly contributed to its relative silence on the concept of mens rea (and the ingredients of criminal liability in general). That has recently changed.’
In their joint dissenting opinion, judges Vehabović, Chanturia, Felici, Yüksel, Ní Raifeartaigh and Kučs equally emphasize that Article 7 should not allow the Court to reassess the domestic finding of criminal liability (Joint Dissenting Opinion, para 2). Indeed, it is the relationship between the Court and domestic criminal judges, and thus the procedural dimension of mens rea, where Yasak’s novelty lies.
After stressing that the Court should not encroach on domestic courts’ territory under Article 7, all dissenting judges point to Article 6 as a more appropriate framework for the national findings of individual criminal liability, arguing that it provides clearer boundaries to prevent overreach into the domestic criminal system.
In some Article 6 cases, the Court indeed applies a more deferential standard. In Kezerashvili, for example, the Court criticizes the ‘relatively brief treatment’ of the mental element of the charged offence by the domestic courts (para 118), implying what a sufficient assessment of mens rea should have looked like. But it stops short of finding a violation of Article 6, applying a deferential standard of arbitrariness or manifest unreasonableness. That said, as Dahlberg or Goss show, the application of the fourth-instance doctrine under Article 6 is inconsistent: the Court at times still conducts a close review of domestic factual and legal findings, depending in part on how urgently it considers that effective protection requires intervention. It is therefore not certain that merely shifting the analysis to an Article 6 perspective really results in a significantly greater respect for the principle of subsidiarity.
Instead, the principle of subsidiarity should be given independent weight regardless of whether mens rea is investigated under Article 6 or 7. It would benefit internal consistency and harmony if a coherent standard of review is made explicit and applied across Convention provisions. Examining the procedural dimension of mens rea, different approaches to such a cross-cutting standard of review are worth considering.
One possibility would be to maintain an equal level of deference across criminal liability cases, prioritizing consistency but forcing a choice between a standard that is either too deferential to offer effective protection or too intrusive to comply with the principle of subsidiarity and the fourth-instance doctrine.
Alternatively, a flexible but transparent standard of review could be adopted. Such a standard could start from a baseline of deference, in line with subsidiarity. Only when certain conditions are met would the Court move closer to reviewing the domestic courts’ findings.
One way of doing so would be through the responsible domestic courts doctrine, as developed by Çalı. Under this model, deference increases where national courts have built a track record of taking Convention principles seriously. The deference granted to domestic courts is, in other words, conditional on the trust that they properly apply the Convention. This approach has the advantage of incentivizing domestic courts to reason carefully about mens rea in a systemic way, building trust. Domestic courts with a history of properly establishing criminal liability would be supervised less intensively than courts that habitually take evidentiary shortcuts and ground convictions on generalized mens rea inferences. But this approach also has limitations. A single abusive prosecution or conviction, even set in a broader context of national authorities generally acting responsibly, remains problematic because of its far-reaching consequences for the accused. As Çalı points out, the responsible domestic courts doctrine may also feed a ‘double standards’ critique by imposing stricter scrutiny on countries with a weaker Convention track record whilst offering less effective protection to applicants from jurisdictions that have earned greater deference.
A second approach ties review intensity to rule-of-law concerns. This factors in dissenting judges’ view that Article 7 is designed as a rule-of-law guarantee (see, for example, G.I.E.M., Joint Partly Dissenting, Partly Concurring Opinion of Judges Spano and Lemmens, para 25). The focus of protection would be less on the individual position of the accused and more on the broader respect for the rule of law. Again, the starting point could be a deferential stance towards the domestic courts. But a more intensive standard would apply where prosecutions or convictions structurally challenge the rule of law. Examples of such cases could include the prosecution of political opposition members, human rights defenders, or lawyers. The difficulty is drawing the line consistently, since rule-of-law concerns can be interpreted expansively and many flawed prosecutions can be brought under its umbrella.
None of these approaches is without cost, and they all deserve further attention. Moreover, they address only the procedural dimension of mens rea. The question of whether the Court can or should play a stronger role in relation to the substantive content of mens rea remains largely open. It is to be seen, as Judge Ní Raifeartaigh cautioned, whether the Court will effectively move ‘towards a new role in shaping the outlines of domestic substantive criminal law’, and add additional requirements to the substantive content of mens rea, or whether it will stick to, strengthen, or limit its current procedural approach.
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