GC IV Commentary Series – Brain Computer Interface-Assisted Interrogations and Articles 27, 31, & 32

Editors’ note: The following series considers ICRC’s 2025 updated Commentary on the Fourth Geneva Convention. Rosa-Lena Lauterbach, Liisi Adamson, and Sean Watts’s introduction to the series is available here.

Any discussion of the treatment of new technology in the 2025 International Committee of the Red Cross GC IV Commentary must properly start with an acknowledgment of the huge scholarly endeavour that the text as a whole represents. The participants and editors are to be congratulated on bringing such an ambitious project as the preparation of new commentaries on all four Conventions to a successful conclusion. The sheer scale of the undertaking is little short of breathtaking.

It is also worth saying that it is the interpretation of treaties by the States that are party thereto that is of paramount importance. Commentaries such as these will of course be of the greatest assistance to States, but it will be how States apply these provisions to the new circumstances that novel and emerging technologies bring that will, in the end, determine how legal interpretations will evolve.

New Technology in the Introduction

The Introduction points out that technologies, unknown in 1949 and at the time of the preparation of Pictet’s 1958 Commentary, have changed the nature of warfare and must of necessity affect our understanding and interpretation of the 1949 texts (paras. 77-82). Mike Schmitt in his valuable and highly authoritative Just Security observations has noted that “new technologies are subject to existing law of armed conflict rules,” that “hand in glove” application of existing rules to new technologies is sometimes precluded, and that in such cases interpretations must “not only be made in good faith and reflect the object and purpose of the rule in question, it must also pass the straight face test.” As an example, Article 107 deals with correspondence by internees in terms of letters and cards, and the Commentary proposes, uncontroversially it is suggested, that the detaining power should also consider more modern forms of communication, listing telephone calls, emails, video calls and recorded messages (para. 5240).

Brain Computer Interfaces in Interrogation

The discussion in this post will centre on a different kind of new technology, namely brain technology. The brain technology on which we will focus is brain-computer interfaces. Brain computer interfaces (BCIs) detect electrical brain activity, determine from it a functional intent, such as a wish to change, move, control or interact with an object, and can then translate that intent or wish into action. The technology, which has to date primarily been applied for medical purposes in the treatment of persons suffering e.g. from advanced paralysis, locked-in syndrome and Parkinsons Disease, has evident applications in warfare and the applicable law has been considered alongside other brain technologies by the author elsewhere. For present purposes the focus will be on the potential use of BCIs in connection with the questioning by the detaining power of persons protected under GC IV, as to which consider, for example, this and this.

GC IV Articles 27, 31, and 32

Article 27 stipulates, so far as relevant, that “protected persons are entitled, in all circumstances, to respect for their persons, their honour … . They shall at all times be humanely treated, and shall be protected especially against all acts of violence or threats thereof and against insults … .” Article 31 stipulates, “No physical or moral coercion shall be exercised against protected persons, in particular to obtain information from them or from third parties.” Article 32 prohibits the taking of “any measure of such a character as to cause the physical suffering or extermination of protected persons in their hands.” Article 32 then applies the prohibition inter alia to “medical or scientific experiments not necessitated by the medical treatment of a protected person” as well as other forms of brutality. In the author’s view, the language used in Article 32 makes it clear that it is concerned with acts of significant gravity.

The Commentary to Article 27

The 2025 Commentary to Article 27 clarifies the meaning to be given to the quoted provisions. It describes respect for person as encompassing respect for physical and moral integrity (para. 2218), thus precluding humiliating treatment, coercion (discussed later), torture, medical experiments (also discussed later) or brutality (para. 2221). The Commentary acknowledges that use of modern technologies in the area of surveillance and personal data collection may infringe dignity, noting that any data collection must adhere to data protection standards (para. 2224). It is highly likely that States will interpret the use of any invasive electrode technology (meaning technology involving inserting the electrodes within the human body) for interrogation purposes as breaching these provisions. It is also likely that non-invasive application of electrodes, say by means of a headset, may be interpreted as either prohibited coercion or a prohibited medical experiment or both.

Pointing out that the notion of respect for honour is not defined in the Convention, discussion suggests it entails “due regard for the sense of value that every person has of themselves” (paras. 2225 & 2226). The link that is made with the person’s reputation, age and standing in their social group makes it clear that humiliating or degrading treatment of any kind is understood to fall foul of the provision. Placing a headset on the scalp of a protected person during interrogation may also be seen by States as humiliating or degrading, particularly if undertaken in certain circumstances.

The pervasive humane treatment obligation is a clear “duty to respect protected persons’ inherent human dignity and inviolable quality as human beings” and the notion is, for good reason, not further defined (para. 2245). Characterising “humane” as “compassionate or benevolent,” the Commentary recognises the context-dependent aspect to humane treatment and usefully points out that this is a positive obligation of humane treatment as opposed to a prohibition of inhumane treatment (para. 2253). “Sensitivity to the individual’s inherent status, capacities and needs, including how these are made to differ for different groups by social, economic, cultural and political structures in society, contributes to the understanding of the requirement of humane treatment under the Geneva Conventions.” (para 2249).

While the prohibition of acts of violence is probably fairly self-explanatory, threats of violence are usefully discussed (para. 2266). Observing the lack of a definition of “threat” in the Convention, the Commentary sensibly bases itself on the ordinary meaning of the word, namely “a statement of an intention to inflict injury, damage, or other hostile action.” A similar, again sensible, approach is taken to the meaning of “insult” namely “a remark or action that treats a person with disrespect or abuse” (para. 2267), implying that protected persons must be protected from disrespectful words or acts. Accordingly, the act of disclosing images, including footage or recordings, of a protected person being subjected to the kind of interrogation discussed below may well, depending on the circumstances, be classed as insulting conduct (paras. 2269 & 2274).

The Commentary to Article 31

The Commentary has much to say about the meaning of coercion. It explains the ordinary meaning of coercion as to persuade an unwilling person to do something by using force or threats. That immediately causes one to wonder whether protected persons are capable of being ‘willing’ in their dealings with the relevant authorities in whose power they are. ‘Willing’ is defined in the Oxford Concise English Dictionary as “1 ready, eager, or prepared to do something; 2 given or done readily.” The key statement in the Commentary is, “The decisive factor in determining whether coercion is being exercised against a protected person is whether the method used is intended to, or has the effect of, depriving or impairing that person’s exercise of free will and autonomy” (para. 2427). Two U.S. publications and the Body of Principles for the Protection of All Persons under Any Form of Detention or Imprisonment (1988), Principle 21(2) are cited in support of this approach.

It will be for the reader to decide whether these sources adequately deal with the issues at hand in the current interpretation exercise. It is surely entirely feasible for a protected person to decide for their own reasons that they are prepared to participate in a BCI-related process, say involving the wearing of a headset, and, given such preparedness, applying the process would not seem to amount to coercion on the part of those asking the questions. If the view is taken that a willing and properly informed participant in the BCI-enhanced questioning process is not being subjected to coercion when that process is conducted in the manner explained to him/her before that willingness was signified, it seems incongruous to suggest that the mere fact that the BCI process involves the detection of inner thoughts per se causes that same process to become coercion. However, as was pointed out earlier, these are matters on which States will need to take a view, and it is the views of States that will, the author suggests, be decisive.

Clearly, the Commentary is right to point out that the particular act(s) must of necessity be considered in the context of the treatment of the individual as a whole to determine whether coercion has been applied (para. 2433). More specifically, it asserts that attempts to gain information from an unwilling protected person through the use, inter alia, of physiological or psychological devices “which impair or deprive protected persons of their free will without being in their interest” are prohibited (para. 2435, citing the UK, Manual on the Law of Armed Conflict, para 8.131, which is actually referring to questioning of prisoners of war to induce them to admit guilt, a rather different matter to that under current discussion). Again, it should be noted that to come within this sentence the person must be unwilling, as to which see the discussion in the previous paragraph. Ultimately, it will be for States to consider carefully whether using BCI technology to make questioning more effective is indeed to be equated with coercion for the purposes of Article 31.

The Commentary to Article 32

So far as relevant to the current discussion, the Commentary indicates that the prohibition extends to painful methods of coercion or restraint (para. 2465). One wonders whether there is space for a de minimis notion falling below the Article 32 prohibition. Undoubtedly if a BCI method of interrogation were to have physical effects on the individual, such as adverse effects on brain performance, this prohibition would become relevant. It is clear that from the ICRC perspective for as long as the short, medium or long-term effects of a BCI-related interrogation are imperfectly understood, not only will it be inherently impossible to obtain free and informed (emphasis intended) consent from the protected person, but the interrogation itself will be regarded as an experiment (paras. 2509-2517). It seems likely that States will take the view that monitoring brain activity in this way is an activity which has medical characteristics; it is therefore highly likely that such activities would on that basis be regarded as breaching Article 32, bearing in mind that the activity is not being undertaken in the medical interests of the protected person.

Some Hypothetical Scenarios

We should now consider four hypothetical scenarios to try to clarify matters.

In the first scenario, a protected person who is believed to have critically important information about a planned enemy mass casualty attack against the civilian population has been detained and is to be questioned. The investigators from the detaining power decide to use a BCI-enhanced interrogation technique. This will involve the insertion of electrodes within the brain as it is assessed that locating them within the brain will improve detection of the relevant electric brain signals. The investigators explain to the protected person what they plan to do and he makes it clear he does not consent.

The second scenario largely mirrors the first, except that the electrodes are inserted sub-cutaneously just below the scalp but outside the cranium, (a) without the consent of the protected person, or (b) with his consent.

In the third scenario, the electrodes are contained in a headset which is worn on the head. The medical risks associated with the process are accurately and fully explained to the protected person. The protected person is a detainee who is being held in a detention camp. It is however explained to the protected person that he has an absolute right to refuse to wear the headset and that his decision in that respect will be respected. He consents to wear the headset.

The fourth and final scenario is a variant of the third. The variation is that the protected person is not a detainee. He has been invited to participate in an investigation the purpose of which has been explained to him. He has been invited to wear the headset, has received the full and accurate explanation of the medical risks and has agreed to wear it. He has been told that he has an absolute right to refuse to wear it.

Applying the Law

Article 32 of GC IV prohibits performing on protected persons “medical or scientific experiments not necessitated by [their] medical treatment.” There is, currently, limited understanding of aspects of brain functioning, of the short, medium and long-term effects of certain brain interventions, and of the link between observed brain activity and specific thoughts. This suggests that there is bound to be a significant degree of medical experimentation associated with all of the scenarios set forth in the preceding section; accordingly, most States are likely to regard all such activities as being prohibited by Article 32.

However, an interesting issue for the purposes of the present discussion is whether those scenarios constitute the exercise of coercion in breach of Article 31. The reference in the dictionary definition of the word to an “unwilling” person seems to be important. Clearly scenarios 1 and 2(a) both amount to coercion and would therefore also be prohibited on that basis. The consent that is given in scenario 2(b) is unlikely to be seen as free and fully informed and will not therefore render the activity lawful. The person is being detained and is a protected person. He is almost certainly unable therefore to give free and informed consent, a consideration that will also impair the consent given in scenario 3. A more detailed discussion of consent lies outside the intended scope of this piece.

So consideration now moves to scenario 4. It would, the author suggests, be inappropriate to condemn all possible situations in which such a scenario might arise as rendering the use of the technology unlawful. It would, the author believes, be for the detaining power to demonstrate clearly that the consent was indeed freely given and that it was, despite possible language issues and the complexity of the relevant technology, a properly informed consent. If, for example, the protected person is keen to establish his bona fides and believes that the use of BCI technology will do so, there may be situations in which it might be lawful for the investigators to accede to his request to use the BCI. However, the employing State would need to be careful to ensure, and later to be able to prove, that what was done was pursuant to the interviewee’s request and that everything that was done was with his specific consent.

Closing Remarks

The sections of the Commentary to which reference has been made are lengthy and very detailed. Inevitably it has only in the available space been possible to refer to the elements thought to be of greatest relevance. As noted in Section 1, how these treaty provisions apply to the technologies that modern science is making available will be determined by the practice of States in the coming years and decades. States will be assisted greatly by the many observations made in the Commentary, but they might not necessarily apply all such observations. It is States that by their treaties and their collective action make international law, and it will be interesting to see how that process evolves in relation to new technologies.

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Air Commodore William H. Boothby retired as Deputy Director of Royal Air Force Legal Services in July 2011. He is Honorary Professor at the Australian National University and also teaches at the University of Southern Denmark and at the Geneva Centre for Security Policy.

The views expressed are those of the author, and do not necessarily reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.

Articles of War is a forum for professionals to share opinions and cultivate ideas. Articles of War does not screen articles to fit a particular editorial agenda, nor endorse or advocate material that is published. Authorship does not indicate affiliation with Articles of War, the Lieber Institute, or the United States Military Academy West Point.

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