4.1 Introduction
Thus far, we have largely considered technologies that are capable of changing persons’ mental states. However, today, a range of technologies are also being developed that can gain insight into the mental realms of others.Footnote 1 One example is the measurement of brain activity, which has enabled researchers to make inferences about individual mental states and faculties. In particular, fMRI and EEG can measure brain activity in a way that allows for inferences about what a person remembers, recognises, thinks or feels. EEG has been used, for example, to identify concealed memories about a criminal offence;Footnote 2 and fMRI has been used to reveal sexual orientation,Footnote 3 political ideologyFootnote 4 or a person’s craving for cocaine.Footnote 5 Recently, various research groups used neurotechnology together with emerging forms of artificial intelligence (AI) to decode mental content from brain activity, with some interesting first results.Footnote 6 According to Brownsword, with the development of these kinds of “brain-reading” technologies, “researchers have a window into the brains and, possibly, into a deeper understanding of the mental lives of their participants”.Footnote 7
In view of these developments, the private sphere of our inner minds may no longer be as inaccessible to others in the way it used to be, raising questions about how the law should protect mental privacy.Footnote 8 Various interpretations of a right to mental privacy have been used in the literature.Footnote 9 Here, we understand this right in a broad sense, as a right not to reveal unexpressed mental phenomena such as mental states and content.Footnote 10
Concerns about mental privacy raised by neurotechnology exceed the domain of medicine and scientific research, as the technology promises to be usable within other contexts too, including education, at work, in the military and criminal justice.Footnote 11 Presumably, these different contexts ask for tailored approaches to protect mental privacy. As before, our focus here is on criminal justice: more specifically, on neurotechnological “brain-reading” to predict future dangerousness – often referred to as “neuroprediction”Footnote 12 – within the context of rehabilitation.
Contemporary debates on the right to mental privacy vis-à-vis neurotechnology often focus on the scope of human rights. Scholars consider whether the protection of mental privacy is covered by the established framework of human rights law or whether it requires the recognition of a standalone and specific human right to mental privacy.Footnote 13 Meanwhile, as we saw in the preceding chapters, effective human rights protection of the mind not only depends on the scope of human rights, but also on their permissible limitations. In this chapter, we consider both the scope and permissible limitations of the right to mental privacy, with specific attention to the question of whether the protection of mental privacy has an absolute dimension in established human rights law.
The outline of this chapter is as follows. In section 4.2, we offer an overview of the human rights protection of mental privacy by three established human rights: (1) the right to privacy, (2) the right to freedom of expression, and (3) the right to freedom of thought. In section 4.3, we consider the interplay between these rights in their protection of mental privacy and explore a threshold criterion for engaging absolute protection by the right to freedom of thought. Along the way, we discuss the implications of our analysis for the non-consensual neuroprediction in criminal justice. Section 4.4 draws conclusions.
4.2 The Protection of Mental Privacy in Human Rights Law
In response to recent calls to recognise a specific human right to mental privacy,Footnote 14 different scholars have argued that such a right is already protected within the existing framework of human rights law.Footnote 15 In particular, they point to the protective scope of (i) the right to privacy, (ii) the right to freedom of expression, and (iii) the right to freedom of thought – all three enshrined in human rights treaties across the globe. By adopting the ‘living instrument approach’ to human rights – which implies that human rights should be interpreted dynamically, in view of present-day conditions, including technological developments – it has been argued that these existing rights are well equipped to offer adequate protection against the non-consensual disclosure of mental states and content (be that either by forced testimony, non-consensual brain-reading, or the hacking of a person’s BCI).Footnote 16 This living instrument approach was initially developed within the case law of the ECtHR,Footnote 17 but has now also been referred to by the UN Human Rights Committee (CCPR) when interpreting and applying the ICCPR.Footnote 18
In this section, we consider how mental privacy is protected by the three human rights mentioned above – the right to privacy, the right to freedom of expression and the right to freedom of thought. We will show that it is evident that mental privacy is protected within the established framework of human rights law. However, much is still unclear about the right’s permissible limitations.Footnote 19 Is mental privacy typically a qualified right, of which infringements can sometimes be justified, like for preventing crime? Or has it, on top of that, an absolute layer, that is, a dimension of mental privacy that can never be overridden in any circumstances?Footnote 20 And if the right to mental privacy has such an absolute layer, which infringements would then be covered by this absolute dimension? The issue of permissible limitations is central to section 4.3.
4.2.1 The Right to Privacy
The right to privacy has a robust foundation in human rights law. It is for instance recognised in the Universal Declaration of Human Rights (Article 12), the International Covenant on Civil and Political Rights (Article 17) and the European Convention on Human Rights (Article 8) – with the latter (as earlier indicated) referring to the right to “respect for private life”.
What is meant by a right to privacy? According to the UN Human Rights Council, privacy can be considered “as the presumption that individuals should have an area of autonomous development, interaction and liberty, a ‘private sphere’ with or without interaction with others, free from State intervention and from excessive unsolicited intervention by other uninvited individuals”.Footnote 21 Several moral rationales have been advanced as underpinning this right to privacy.Footnote 22 Many scholars emphasise the instrumental value of privacy for enabling freedom and autonomy, with some arguing (more strongly) that without the protection of private life, individual freedom and autonomy would be impossible.Footnote 23 Other scholars suggest that privacy has non-instrumental value, or value in-and-of-itself, such that in its absence people would fail to flourish.Footnote 24 And still others argue that a right to privacy is justified for respect-based reasons – that is, that refraining from intruding on a person’s privacy is necessary to respect that individual as a person or being “with sensibilities, ends, and aspirations of their own”.Footnote 25
The right to privacy is relevant for our present analysis because obligations to reveal private mental phenomena – for example, using non-consensual brain-reading – are likely to infringe the right to privacy. The right to privacy is, after all, both widely applicable and broad in scope – both in the case of Article 17 ICCPR and Article 8 ECHR. It applies to state agents who might interfere with a person’s privacy. It also requires that states adopt legislative and other measures to give effect to the protection of privacy.Footnote 26 And the right’s breadth means that it should protect against a wide spectrum of privacy interference, including by modern means.
Looking first to the international context, Article 17 ICCPR “is a short but versatile provision, capable of answering a broad diversity of unlawful or arbitrary incursions into privacy (…) which could not have been specifically foreseen by its drafters”.Footnote 27 For example, Article 17 ICCPR applies to AI systems that process personal data for algorithmic decision-making.Footnote 28 It also covers the protection of metadata, as such data, when analysed and aggregated, “may give an insight into an individual’s behaviour, social relationship, private preference and identity”.Footnote 29 Furthermore, the UN High Commissioner for Human Rights, when discussing the right to privacy, refers to data-driven technologies that “increasingly enable States and business enterprises to obtain fine-grained information about people’s lives, make inferences about their physical and mental characteristics and create detailed personality profiles”.Footnote 30 The High Commissioner considers informational privacy to be particularly important in the age of modern technology and digital environments.Footnote 31 The High Commissioner also holds that the right to privacy of Article 17 ICCPR is not only impacted by the examination and use of personal data by humans or algorithms. Even the mere generation and collection of data relating to a person’s identity, family or life will affect the right, “as through those steps an individual loses some control over information that could put his or her privacy at risk”.Footnote 32
In the European context, the ECtHR emphasises that “private life” is a broad concept that does not lend itself to exhaustive definition.Footnote 33 It is clear though that the right to private life covers the protection of “personal data”. Referring to Article 2 of the Data Protection Convention 1981, the ECtHR defines personal data as “any information that relates to an identified or identifiable individual”.Footnote 34 According to Article 3 of the EU Law Enforcement Directive (2016/680), “personal data” means “any information relating to an identified or identifiable natural person (‘data subject’); (…) such as a name, an identification number, location data, an online identifier or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that natural person”.Footnote 35
The ECtHR considers the protection of personal data of fundamental importance to the enjoyment of the right to respect for private life and holds that Article 8 ECHR comprises “the right to a form of informational self-determination, allowing individuals to rely on their right to privacy as regards data which, albeit neutral, are collected, processed and disseminated”.Footnote 36 When considering whether personal information relates to someone’s “private life” in the meaning of Article 8 ECHR, and whether the collection, storage or use of that information infringes this right, the ECtHR has due regard to: (1) the nature of the records, (2) the results that may be obtained, (3) the specific context in which the information has been recorded and retained and (4) the way in which these records are used and processed.Footnote 37
Examples of infringements of Article 8 ECHR in the context of criminal justice include taking and retaining a photograph on arrest, yielding fingerprints and cellular samples for DNA analysis, and the collection of personal information via a GPS tracking system.Footnote 38 Plausibly, the right to privacy also applies to the employment of other emerging technologies that yield personal data, including neurotechnological brain-reading such as with fMRI and EEG.Footnote 39 Such brain-reading could moreover produce sensitive personal data, allowing the drawing of inferences about, for example, emotions, sexual orientation and/or mental health.
Given its broad scope, there is reason to suppose that the right to privacy as guaranteed by Articles 17 ICCPR and 8 ECHR also implies a right to mental privacy. It is reasonable to suppose, first, that the ethical values thought to ground a right to privacy – that is, the values of freedom and autonomy, human flourishing, and respect for persons – are crucially advanced by the protection of mental privacy. Think of how a lack of mental privacy would likely limit the freedom and “natural flow” of people’s ideas (and hence actions),Footnote 40 and of how some degree of mental seclusion and separation is plausibly necessary for beings like ourselves to function and flourish.Footnote 41 Second, legally, it is indeed plausible that a right to mental privacy is ipso facto covered by the general right to privacy. As Bublitz argues, it seems evident that the latter established right covers the former: “[s]everal international instruments protect a general right to privacy or private life. According to the standards of legal interpretation, this abstract right implies more context or domain-specific variations. In other words, mental privacy is implied by the more general right to privacy”.Footnote 42
Many lawyers will confirm and endorse this view. For example, already in their seminal article on the right to privacy published in 1890, Warren and Brandeis observed that “the common law secures to each individual the right of determining, originally, to what extent his thoughts, sentiments, and emotions shall be communicated to others”.Footnote 43 This legal protection, they argued, is merely an instance of the general right to be let alone – the right to privacy – which could be invoked to protect against “invasion either by the too enterprising press, the photographer, or the possessor of any other modern device for recording or reproducing scenes and sounds”.Footnote 44 Over a century later, the UN Special Rapporteur on the Right to Privacy (Article 17 ICCPR) warned “that constantly developing technologies pose important challenges for the protection of privacy: these technologies may reveal the most intimate behaviour, wishes, preferences and indeed the very thoughts of individuals in ways that previously were not possible”.Footnote 45 As the UN Special Rapporteur on Freedom of Religion or Belief highlights, in the United States, “courts recognise that an individual right to privacy encompasses mental privacy”.Footnote 46 Likewise, in the European legal context, it has been argued that the right to respect for private life pursuant to Article 8 ECHR covers, among many other things, the protection of mental privacy.Footnote 47 These observations seem to confirm that a right not to reveal thoughts, emotions, sentiments, preferences, wishes, or other private mental phenomena – a right to mental privacy – is covered by the general right to privacy.Footnote 48
Non-consensual neuroprediction arguably infringes the right to privacy,Footnote 49 notwithstanding that the right is unlikely to prohibit neuroprediction across the board. Recall that infringements of the right to privacy can be justified under both Article 17 ICCPR and 8 ECHR if they have an non-arbitrary basis in domestic law and are necessary for and proportionate to a legitimate purpose, such as the prevention of crime and disorder.Footnote 50 Given that permissible privacy infringements have included, among many other things, secret surveillance and DNA testing for the purpose of preventing crime and protecting the rights of others,Footnote 51 and legally obliging witnesses to reveal their knowledge and memories about a criminal offence in court,Footnote 52 the right to (mental) privacy is unlikely to prohibit, in principle, all non-consensual applications of neuropredictive technologies that reveal private information about brain and mental states for the purpose of preventing crime.Footnote 53 We return to this in section 4.3.
4.2.2 The Right to Freedom of Expression
The secrecy of our mental states and content also receives protection from the right to freedom of expression, guaranteed by Articles 19 ICCPR and 10 ECHR.Footnote 54 The relevance of this right to the protection of mental privacy lies in its negative aspect, guaranteeing the freedom not to express oneself. This negative freedom is something we have an interest in possessing. We have an interest in having a “reasonable measure of control” over the ways in which we express and present ourselves to othersFootnote 55 – consider how expressing ourselves might sometimes open us up to social scrutiny and potential social harm.
The freedom not to express oneself was clearly emphasised by the European Commission on Human Rights (EComHR) in the case of Strohal/Austria, where the EComHR argued that “the right to freedom of expression by implication also guarantees a ‘negative right’ not to be compelled to express oneself, i.e., to remain silent”.Footnote 56 The Grand Chamber of the ECtHR “does not rule out that a negative right to freedom of expression is protected under Article 10 of the Convention, but finds that this issue should be properly addressed in the circumstances of a given case”.Footnote 57 Recently, the ECtHR confirmed that the right to freedom of expression has a negative aspect: “A holistic protection of the freedom of expression necessarily encompasses both the right to express ideas and the right to remain silent; otherwise, the right cannot be practical or effective.”Footnote 58 Compelling the applicants to express a message with which they disagreed infringed the right’s negative aspect in this case. In the same vein, the General Comment to Article 19 ICCPR states: “Freedom to express one’s opinion necessarily includes freedom not to express one’s opinion.”Footnote 59
This is, in our view, a logical implication of the freedom to express oneself, which entails that the expression of opinions, ideas and other information is freely chosen – that one can freely choose between expressing and not expressing oneself. A right not to express opinions, ideas, feelings, knowledge and other kinds of information corresponds, in our view, almost seamlessly to a right to mental privacy – at least, if one understands this right as a right not to reveal unexpressed mental phenomena such as mental states and content.
Apart from few exceptions,Footnote 60 the content of an expression is irrelevant to the applicability of the right to freedom of expression.Footnote 61 Referring to the work of the CCPR, Taylor writes that the freedom of expression protects the dissemination of content “which many, in some cases most, may find unwelcome or repugnant (spanning pornography, offensive art, anti-Semitic messages or messages in support of terrorism)”.Footnote 62 Likewise, according to the ECtHR, the right to freedom of expression is “applicable not only to ‘information’ or ‘ideas’ that are favourably received or regarded as inoffensive or as a matter of indifference, but also to those that offend, shock or disturb”.Footnote 63 As such, the scope of the right to freedom of expression is considered “extremely broad”.Footnote 64 The logical implication of this is that the negative freedom not to express oneself is broad too.
Interestingly, the right to freedom of expression protects not only the substance of information but also a diverse range of forms and means by which information is expressed, transmitted and received.Footnote 65 For example, among many other things, the ECtHR has applied the right to speech, poetry, painting, radio, film, handcuffing oneself to a barrier during protest, disrupting foxhunting by blowing a hunting horn and performing a puppet show satirical of politicians.Footnote 66 The General Comment on Article 19 ICCPR mentions spoken, written and sign language, non-verbal expression such as through images, objects of art and dress, and legal submissions.Footnote 67
So, both Articles 19 ICCPR and 10 ECHR guarantee a broad right to freedom of expression. They protect opinions, ideas, facts, value statements and other information of almost any content, transmitted through practically any means, which may, in theory, also concern neurotechnological means, such as fMRI, EEG and BCI. Crucially, they also protect the freedom not to express; and given this, the right to freedom of expression likely protects against the obligation to disclose private information, such as mental phenomena, through neuroprediction.Footnote 68
Similar to the right to privacy, the right to freedom of expression pursuant to Article 10 ECHR will not prohibit, in principle, the non-consensual use of neuropredictive tools, as the right may be subjected to “formalities, conditions, restrictions or penalties” that have a legal basis and are necessary within a democratic society for the legitimate interest of, among other things, preventing disorder and crime.Footnote 69
Note, however, that Article 19 ICCPR distinguishes between, respectively, the right to hold opinions without interference and the freedom to express information and ideas of all kinds. Whereas the latter freedom to express information (including opinions) may be limited, for example for the protection of public order, the former may not: the right to freely hold opinions is an absolute right, not susceptible to restriction or limitation,Footnote 70 and this right “includes [the] freedom not to express one’s opinion”.Footnote 71 Hence, strictly speaking, the protection of mental privacy, in the form of privacy of opinion, is absolute under Article 19 ICCPR. Regarding neuroprediction in criminal justice, the relevance of this absolute component of Article 19 ICCPR will probably be limited. Neuropredictive applications in this domain are likely to reveal information about phenomena such as self-control and emotional processing, and thus hardly qualify as revealing the person’s opinion about something. Infringement of the absolute right to freedom of opinion is, therefore, unlikely. Article 19 ICCPR thus does not necessarily prohibit all non-consensual usage of neuroprediction – provided that such usage does not qualify as compelling persons to express “opinions”.
4.2.3 The Right to Freedom of Thought
The right to freedom of thought, conscience and religion is guaranteed by Articles 18 ICCPR and 9 ECHR, and is often espoused as being central to the enjoyment of other basic rights and liberties, as well as being crucial for democracy.Footnote 72 The right is often considered to consist of an internal and external dimension, offering protection within the so-called forum internum and forum externum.Footnote 73 The internal dimension of the right is often considered to be absolute, not permitting “any limitations whatsoever”.Footnote 74 It covers the freedom to have, change and adopt a religion, conviction and thought. In the external dimension, the right guarantees the qualified freedom to manifest religion and belief. The manifestation of thought, however, is not protected by the right to freedom of thought pursuant to Articles 18 ICCPR and 9 ECHR. These Articles only protect unmanifested thought. The manifestation of thoughts, such as through speech and expression, is protected by the right to freedom of expression.Footnote 75
In the internal, absolute dimension, the right to freedom of thought is generally considered to guarantee three substantive freedoms: (1) that no one is compelled to reveal their thoughts, (2) that one’s thoughts are not impermissibly altered and (3) that no one will be sanctioned for their thoughts.Footnote 76 The UN Special Rapporteur on Freedom of Religion or Belief holds that the first freedom implies that mental privacy is a “core attribute” of freedom of thought and also includes, arguably, a right to remain silent.Footnote 77 According to the Rapporteur, the freedom not to be compelled to reveal one’s thoughts is currently under threat by, inter alia, neurotechnologies that allow the drawing of inferences about a variety of unexpressed mental states.Footnote 78 Likewise, considering the potential of neurotechnological lie detection and memory detection in criminal justice, Bublitz finds it “hard to imagine a better paradigmatic case against which freedom of thought should provide protection”.Footnote 79
However, the scope of the mental privacy protection afforded by the right to freedom of thought depends, considerably, on how one interprets “thoughts” in the context of this right. As discussed in Chapter 3, some have argued for a broad interpretation, such that the right protects any mental state with content and thinking as a mental process (robust-scope view).Footnote 80 For example, O’Callaghan et al. have argued that thought in the meaning of Articles 18 ICCPR and 9 ECHR “can be understood as encompassing all forms of unmanifested mental activity, including ‘deliberation, imagination, belief, reflection, reasoning, cogitation, remembering, wishing, sensing, questioning, and desiring’”.Footnote 81 On such an understanding, the freedom not to reveal private “thoughts” comes down to a broad right to mental privacy – that is, a right not to reveal any unexpressed mental state and content. As also discussed in Chapter 3, for the interpretation of the right to freedom of thought pursuant to Article 18 ICCPR, such a robust interpretation receives some support,Footnote 82 also from the UN Special Rapporteur on Freedom of Religion or Belief.Footnote 83
Adopting such a broad scope would have profound effects on the human rights protection of mental privacy: if we assume a broad understanding of “thought”, the privacy protection offered by the right to freedom of thought will considerably overlap with both the right to privacy and the right to freedom of expression. All three rights will then imply a right not to reveal unexpressed personal mental states and content. This poses a theoretical difficulty, as the protection of mental privacy by the right to freedom of thought is considered absolute, as opposed to the qualified protection offered by the right to privacy and, in the European context, the freedom of non-expression. This raises the question: How should the law distinguish between the applicability of either absolute or qualified mental privacy protection?Footnote 84 The answer to this question will be crucial for the permissibility of interferences with mental privacy, including through non-consensual neuroprediction in criminal justice. We explore this question in the next section.
4.3 Towards a Threshold for the Right to Freedom of Thought?
For the remainder of this chapter, let us assume a broad scope of the right to freedom of thought along the lines of the robust-scope view.Footnote 85 Let us also assume that, therefore, mental privacy is protected by both the absolute right to freedom of thought and the qualified rights to privacy and to freedom of expression. We then have the following question: How should judges determine which interferences with mental privacy would engage either absolute or qualified protection? How should they determine when the absolute right to freedom of thought applies to a specific case of privacy interference, such as the neuroprediction of convicted persons?Footnote 86
At present, neither the law, jurisprudence, literature nor the report on freedom of thought by the UN Special Rapporteur provides clarification about this issue. However, in recent work, different scholars have suggested developing a severity threshold to determine whether a mental interference, such as revealing private mental phenomena with neurotechnology, would infringe and therefore violate the absolute right to freedom of thought.Footnote 87 For example, Bublitz proposes to adopt the “seriousness” of the privacy interference as a guiding principle for determining whether revealing (information about) unexpressed thought infringes the right.Footnote 88 He suggests a threshold for infringement that requires “interferences of some intensity or gravity”, the assessment of which may draw on a range of factors, including the importance of the content of the thought, the nature of the interference and the intrusiveness of the means by which a thought is detected.Footnote 89
Developing such a threshold for the applicability of a specific human right is not uncommon in human rights law.Footnote 90 It may indeed be a suitable approach for distinguishing absolute from qualified protection of mental privacy – that is, for distinguishing between the application of either the right to freedom of thought or the right to privacy/freedom of non-expression.Footnote 91 Meanwhile, it raises the question of which “interferences” can be considered “serious” enough to infringe the absolute right to freedom of thought.Footnote 92 There are different ways to explore and examine this question, including the use of thought experiments and involving ethical considerations and psychological or neuroscientific views on the intensity of different types of interference with thought.Footnote 93 Furthermore, the law itself may provide some helpful guidance.
As Christoffersen writes, “[t]he relationship between relative and absolute rights will often be one of lex generalis/lex specialis: the relative provisions provide a general and wider measure of protection at a lower level, whereas the absolute provisions generate more specific and narrower protection at a higher level”.Footnote 94 Consider, for example, the protection of bodily and mental integrity under the ECHR.Footnote 95 The qualified right to respect for private life in Article 8 ECHR provides broad protection of bodily and, possibly, also mental integrity in a large variety of instances.Footnote 96 On top of that, the prohibition of ill-treatment of Article 3 ECHR provides further absolute – though much narrower – protection of bodily and mental integrity, that is, protection against a category of grave and harmful interferences.
The ECtHR has developed a legal mechanism to distinguish absolute from qualified protection of bodily and mental integrity under Article 3 and 8 ECHR. In order to determine the applicability of the absolute prohibition of ill-treatment – over and above the qualified right to respect for private life – the ECtHR employs a severity threshold: Article 3 ECHR only applies to treatment attaining a “minimum level of severity”. Although the prohibition of ill-treatment is absolute, the severity threshold is typically relative and depends on all circumstances of the individual case.Footnote 97 These include certain characteristics of the treatment (like its physical and mental effects and the manner and method of its execution), the context in which the treatment was imposed (such as in prison or in an atmosphere of heightened tension and emotions), characteristics of the victim (like one’s sex, age and state of health) and the purpose for which the treatment was inflicted together with the intention and motivation behind it.Footnote 98
The ECtHR considers these factors relevant for distinguishing absolute from qualified protection of bodily and mental integrity. We suggest that it is worth exploring whether these factors also prove useful for distinguishing absolute from qualified protection of mental privacy,Footnote 99 though we acknowledge the differences between integrity and privacy rights. In sections 4.3.1, 4.3.2 and 4.3.3 we consider the potential relevance of (1) characteristics of the interference, (2) the context of the interference and (3) the characteristics of the victim for distinguishing absolute from qualified protection of mental privacy. We do not consider the potential relevance of the purpose or intention of an interference – the fourth factor mentioned above. Including such a factor would ultimately amount to including a proportionality test, adding a qualification to the absolute protection of mental privacy.Footnote 100 The question, then, becomes whether a certain intervention, in a certain context, given the characteristics of the victim, is proportionate in light of the purpose or intention of the intervention. However, what we aim to delineate here is the type of cases that would receive absolute protection from the right to freedom of thought, that is, regardless of the importance of the purpose of the interference.
Before proceeding, we wish to clarify that, in line with the current status of the law, we assume that the right to freedom of thought is an absolute human right. We are aware of recent suggestions to formulate strict exceptions or inherent limitations to the right,Footnote 101 and we think these suggestions deserve serious consideration.Footnote 102 We also recognise that many theorists doubt that trulyabsolute rights exist at the level of fundamental morality. As Brownlee puts it, “when the numbers [or stakes] get large enough, we all tend to become consequentialists”.Footnote 103 However, in this explorative section we follow the dominant view in human rights law and accept that there is value in recognising a limited number of human rights as absolute at the level of law (e.g., the prohibition of torture, the prohibition of slavery, and some aspects of the freedom of thought, conscience and religion). The question of how to distinguish absolute from qualified protection of mental privacy therefore arises.
4.3.1 Characteristics of the Privacy Interference: Means and Targeted Mental Phenomena
A general characteristic of an interference with mental privacy that may be relevant for distinguishing the applicability of the absolute right to freedom of thought from the qualified right to privacy or freedom of expression, relates to the method of revealing personal mental states. Of course, this can be interpreted in different ways, however, as we will explain, we consider this aspect in terms of “control” – more specifically the level of control the employed method leaves to the person whose mental states are being revealed. Regarding interventions that aim to change or modulate a person’s mental states (like neurointerventions), Bublitz has argued that the level of self-control a person retains should be relevant to the applicability of the absolute right to freedom of thought, as infringements of the freedom of thought typically disrespect a person’s control over their own thoughts and thinking. According to Bublitz: “This is a necessary, but not a sufficient condition, and it forms part of a test of infringement: Does an intervention respect the other as a free and self-controlled thinker; or does it undermine or bypass control? The latter infringes freedom of thought, the former may not.”Footnote 104
A similar line of reasoning may be explored regarding the privacy dimension of the right to freedom of thought.Footnote 105 One of the dominant approaches to information privacy conceives of privacy as a right to control personal information.Footnote 106 For example, as Fried argued, “privacy is not simply an absence of information about us in the minds of others; rather it is the control we have over information about ourselves”.Footnote 107 The emphasis on controlling personal information is also reflected in the law. For instance, under Article 8 ECHR, the ECtHR has recognised a right to “informational self-determination”.Footnote 108 Furthermore, recital 7 of the European GDPR states firmly that “natural persons should have control of their own personal data”. The value of controlling personal information, including mental states, seems also relevant to mental privacy under the right to freedom of thought. As the drafters of Article 9 ECHR put it, the right to freedom of thought, conscience and religion intends to protect “not only from ‘confessions’ imposed for reasons of State, but also from those abominable methods of police enquiry or judicial process which rob the suspect or accused person of control of his intellectual faculties and of his conscience”.Footnote 109
It appears generally accepted that within the forum internum the right to freedom of thought is absolute. Hence, absolute human rights protection of mental privacy, one could argue, may at least be warranted regarding means that disclose thoughts directly from the forum internum, that is, means that do not involve any form of expression and conscious control whatsoever, and to which consent is not obtained. An example of such means could be the hacking of a person’s BCI, which seems to destroy the core essence of mental privacy, that is, the person’s ability to control the disclosure and dissemination of private mental content.Footnote 110 Bublitz has argued in the same direction, proposing that the “main condition prompting freedom of thought protection is the revelation of unexpressed thoughts”, which means that “the rightholder has not manifested them through voluntary actions such as speech”.Footnote 111 He submits that neuroimaging “does not work through the person as a subject – by coercing or compelling her – but bypasses her as a subject to extract unexpressed thought. This breach of the inner sphere may suffice to reach the required level of seriousness”.Footnote 112
Following this line of thought, the non-consensual use of neuroimaging for the purpose of risk assessment in criminal justice may, in some instances, be considered to infringe the absolute right to freedom of thought – that is, when they do not involve any form of expression and conscious control whatsoever. However, since identifying relevant mental phenomena, such as certain intentions or inclinations, with neurotechnology will usually require at least some engagement from the person themselves (e.g., performing a task, observing stimuli, not manipulating the assessment), it is questionable whether their non-consensual use can regularly be considered to completely bypass or undermine the person’s mental control.
Another relevant characteristic of mental privacy interference that could contribute to determining the “seriousness” of the interference relates to the precise mental phenomenon that is targeted and revealed. The significance of a person’s interests in not revealing information about certain types of mental states and content may be important.Footnote 113 For example, there may be good reasons to assume that the significance of the interest in not revealing one’s political or religious ideas could justify absolute protection from the freedom of thought.Footnote 114 The significance of the person’s interest in not revealing one’s sexual preferences may be another example. Meanwhile, the personal interest in having one’s mental privacy respected may be weaker in relation to more trivial information about mental phenomena, of which absolute human rights protection would be less persuasive. One could think of a person’s memory about a specific event, like the lovely sunset one experienced in Italy last summer,Footnote 115 a person’s intention to grab a cup of tea during the coffee break or one’s opinion about a new Netflix series.
Whereas many would probably agree that the secrecy of political opinions deserves stronger privacy protection than the secrecy of a preference for tea or coffee,Footnote 116 much of the area in between is grey. What about emotions: whether one feels happy or sad? What about an opinion about a colleague? A memory about a criminal offence? Or a wild fantasy of becoming famous one day? Is the personal interest in keeping information about these mental states secluded from others significant enough to engage absolute mental privacy protection? It is hard to answer this question in isolation from other relevant considerations – perhaps most notably, the context within which one is obliged to reveal information about them. For instance, in the future, neuropredictive tools may well reveal information about different types of mental phenomena, ranging from emotional responses and reduced self-control to sexual orientation and information indicative of mental disorders. Whereas, in general, the significance of the personal interest in not revealing these types of information plausibly differs between them, their disclosure and use in the context of criminal justice for risk assessment may have similar adverse effects on the interest of personal liberty. For example, all such information could potentially contribute to the assessment of a certain expected risk of recidivism and, therefore, leading to the rejection of a parole request. Let us turn to considering the relevance of the context of a mental privacy interference in more detail in the next section.
4.3.2 Context of the Privacy Interference
The significance of the personal interest in not disclosing mental states – which may be a relevant consideration for granting absolute protection, as discussed in the previous section – plausibly depends on the context within which one is obliged to do so. In some contexts, being forced to revealing one’s true views and ideas may be unpleasant but is unlikely to harm vital personal interests. Meanwhile, in other contexts, the revelation of private ideas, thoughts and feelings may have significant detrimental effects, ranging from not being offered a job, to the deprivation of liberty, and even death.
Consider, for instance, how the risk of being harmed by expressing one’s homosexual feelings and desires depends significantly on the country (legal system) in which they are disclosed. Or consider the obligation to provide information about one’s emotions and intentions in the context of requesting a gun license, which could result in the rejection of one’s request, compared to being obliged to disclose emotions and intentions in the context of a criminal prosecution, which could result in a conviction. Whereas the former seems not to face any principled objections, and many would feel it should be permissible, the latter is in principle prohibited in most legal systems by the right to silence and the privilege against self-incrimination,Footnote 117 which, according to some, primarily aims to protect the accused’s mental privacy.Footnote 118 As such, the context wherein one reveals information about specific mental phenomena appears to affect the personal interest in (not) doing so. Perhaps, this could inform our normative analysis of whether, when and which mental states deserve either absolute or qualified protection from human rights.
These intuitions about different informational norms applying in different (social) contexts are reminiscent of Nissenbaum’s philosophical account on information privacy. In her book Privacy in Context, Nissenbaum argues that privacy concerns should not be limited solely to concerns about control over and access to personal data. Rather, privacy is also about context-dependent social norms that govern the “appropriate flow of information” in different settings and relationships, ranging from family, friends and the workplace to schools, health care and law enforcement. Nissenbaum calls this conception of privacy “contextual integrity”,Footnote 119 which, in practice, means that different rules and norms apply about confidentiality, access to and control over personal data across different contexts, such as the context of friendship, doctor-patient relationships and criminal justice.Footnote 120
Although the dominant account in law conceives of privacy as control over personal information, the ECtHR does consider the context of an interference with personal data relevant under Article 8 ECHR. In determining whether an interference with personal data infringes the right to respect for private life, “the Court will have due regard to the specific context in which the information at issue has been recorded and retained”.Footnote 121 Perhaps, a context-based understanding of privacy may also inform our legal thinking about attributing either absolute or qualified protection to interferences with mental privacy. This may be particularly relevant to the evaluation of mental privacy interference in the context of criminal justice, such as through neuroprediction, since the personal interests at stake in this context are often significant, such as the limitation of personal liberty and a possible decline of well-being as a result of extending the duration of incarceration (due to one’s being at “high risk” of reoffending).
4.3.3 Characteristics of the Victim: Vulnerability
When assessing, under Article 3 ECHR, whether a specific treatment attains a minimum level of severity and thus engages absolute protection of bodily and mental integrity from the prohibition of ill-treatment, the ECtHR takes account of a variety of personal characteristics of the victim, such as their sex, age and state of health. In the case of Khlaifia and Others/Italy, the Grand Chamber phrases and, arguably, broadens this factor by appealing in more general terms to the victim’s vulnerability: “In order to determine whether the threshold of severity has been reached, the Court also takes other factors into consideration, in particular (…) [w]hether the victim is in a vulnerable situation, which is normally the case for persons deprived of their liberty.”Footnote 122
Various groups of people have been identified as being particularly vulnerable in the ECtHR’s case law, including children, people with mental disabilities and persons deprived of their liberty.Footnote 123 These groups are considered vulnerable because they are more susceptible to harm than others.Footnote 124 By recognising them as vulnerable, the ECtHR acknowledges their challenges and specific needs and underlines the duty of states to provide enhanced protection of people belonging to these groups.Footnote 125
Could a person’s vulnerability also be relevant to the question of whether an interference with mental privacy should engage either absolute or qualified protection from human rights? Some people may be more vulnerable to (severe) interference with their mental privacy than others. Think, for example, of those who are illiterate, using a BCI for non-medical purposes such as in gaming, who might be less able to understand, oversee and, therefore, resist the potential threats to mental privacy posed by emerging neurotechnology. Other vulnerable persons may include minors, elderly, people with mental disabilitiesFootnote 126 and convicted persons deprived of their liberty who are ‘offered’ neurotechnology.Footnote 127
Much has been written about different types and conceptions of “vulnerability” and how it could be relevant to the law. Here, we wish to briefly point to the work of Robert Goodin, who argues that governments, private companies and natural persons bear a special responsibility for protecting those who are particularly vulnerable.Footnote 128 Goodin conceives of vulnerability as a relational concept. People are vulnerable to the actions of others – that is, to the infliction of harm on them by others. This kind of relational vulnerability creates a special responsibility of those to whom others are particularly vulnerable: “If A’s interests are vulnerable to B’s actions and choices, B has a special responsibility to protect A’s interest; the strength of this responsibility depends strictly upon the degree to which B can affect A’s interests.”Footnote 129 This special responsibility applies primarily to the protection of so-called “vital interests” or “primary goods”, such as food, shelter, physical and mental health, self-respect and civil liberties (which includes the civil liberty of mental privacy).Footnote 130
Goodin argues that a person’s vulnerability or dependency does not really cause moral concern in and of itself. However, it “necessarily creates opportunities for the strong to exploit the weakness of those who are vulnerable and dependent”, and this is what causes moral concern and requires taking special responsibility to protect the vulnerable.Footnote 131 Exploitation is often defined as taking unfair advantage of other people, which implies a normative judgement about those who exploit.Footnote 132 Perhaps, this could be relevant to the law too, as a person’s vulnerable status may not only increase their risk of being harmed (i.e., having their mental privacy interfered with) but also add an additional wrong when others, such as government officials, take unfair advantage of a person’s vulnerable status by yielding, processing and/or disclosing intimate information about people’s private mental states and content.
Possibly, this additional wrong could be relevant to determining whether an interference with mental privacy should engage either absolute or qualified human rights protection.Footnote 133 As Goodin argues, in no case should people’s vulnerabilities “be so severe and asymmetrical that one party has exclusive, discretionary control over resources that the other needs to protect his vital interests”.Footnote 134 He calls this the principle of “preventing exploitable vulnerabilities”. If we apply this principle to the case of protecting mental privacy, absolute prohibition of discretionary control by others over revealing mental content of (certain) vulnerable persons may be appropriate.Footnote 135 Whether and how this principle of “preventing exploitable vulnerabilities” could indeed be relevant to the application of the absolute right to freedom of thought, and whether it would fit within the ICCPR and ECHR frameworks, merits further elaboration.
Regarding the neuroprediction of convicted persons, different vulnerabilities could, potentially, be relevant. First, the vulnerable position arising from incarceration – that is, the incarcerated person’s “vulnerability at the hands of the authorities, who exercise complete control over her throughout her detention”.Footnote 136 Second, research shows that incarcerated persons have high rates of psychiatric disorders,Footnote 137 which could add to a person’s vulnerability.Footnote 138 Third, one could argue that, with the rise of neurotechnologies, every person is inherently vulnerable to the exploitation of the lack of control we have over the neural correlates of mental states. As Bublitz argues, “many neuroimaging methods exploit the fact that people lack control over the physiological correlates of thought”.Footnote 139 Whether, and, if so, to what extent, these different forms of vulnerability should indeed be relevant to the application of the absolute right to freedom of thought is an open question in need of further research.
4.3.4 Brief Recap
In this section, we explored how the law could distinguish between the qualified protection of mental privacy, provided by the right to privacy and right to freedom of expression, and the absolute protection offered by the right to freedom of thought. This will be highly relevant for the permissibility of mental privacy interferences, which are likely to occur in neurorehabilitation. Analogous to the “minimal level of severity” threshold for the applicability of Article 3 ECHR, we explored the possibility of developing a severity threshold for infringing the privacy dimension of the absolute right to freedom of thought. For the construction of such a threshold, we suggested four potentially relevant factors: (1) the method of revealing mental phenomena, focusing on the level of the subject’s control; (2) the significance of the personal interest in not revealing specific mental phenomena; (3) the context of the privacy interference; and (4) the person’s vulnerability.
4.4 Concluding Remarks
The personal interest in mental privacy receives considerable protection from the ICCPR and ECHR. This protection is anchored across three different human rights: the right to privacy, the right to freedom of expression and the right to freedom of thought – the latter being considered an absolute right. Some forms of non-consensual neuroprediction in criminal justice plausible interfere with mental privacy and, therefore, potentially infringe the right to privacy and the freedom of non-expression. Regarding the right to freedom of thought, our analysis showed that the right’s relevance largely depends on how one interprets “thought”. On a broad understanding, which receives some support regarding Article 18 ICCPR (as opposed to Article 9 ECHR), some forms of neuroprediction might be capable of revealing protected “thoughts”. One could think of brain data allowing to draw inferences about sexual orientation, or about an intention to commit a criminal offence.
In this chapter, we also explored how the law could distinguish between the absolute protection of mental privacy offered by the right to freedom of thought, and the qualified protection provided by the right to privacy and right to freedom of expression. This issue will be crucial for the permissibility of mental privacy interference, such as through neuroprediction. We considered the possibility of developing a severity threshold for infringing the privacy dimension of the absolute right to freedom of thought. For the construction of such a threshold, we identified four potentially relevant factors: (1) the method of revealing mental phenomena, (2) the significance of the personal interest in not revealing certain mental phenomena, (3) the context of the privacy interference and (4) the person’s vulnerability.
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