The Neurological Battlefield: Neurotechnology and the challenges for the laws of war
Based on “Neurotechnology & the law: military law” by Aidan Lloyd, Senior Associate at Hugh James, and Harry Lambert at Outer Temple.
Neurotech dilemmas in laws of war.
What happens when a soldier’s equipment can act before they consciously decide to do so? Or when a technology developed to treat brain injury is adapted to improve performance on the battlefield? Military neurotechnology raises questions that reach well beyond the capabilities of the equipment itself.
Nathan Beauchamp-Mustafaga of the RAND Corporation describes an emerging era of “cognitive domain operations”, extending military activity into the realm of the human mind. NATO’s Allied Command Transformation also identifies cognitive warfare as an emerging field, with efforts to influence and disrupt how people process information and make decisions.
International humanitarian law (IHL), often called the laws of war, relies on distinctions between combatants and non-combatants, and between the person making a decision and the equipment carrying it out. Technologies that connect the brain more closely to military systems may blur those boundaries.
Drawing on the original article, this blog explores five areas where neurotechnology could challenge the way those rules work.
1 Recognising when a soldier is out of action
The laws of war protect people who are hors de combat, meaning “out of action”. They prohibit attacks on anyone recognised, or who should reasonably be recognised in the circumstances, as being in that position..
This can include someone in the enemy’s power, someone clearly expressing an intention to surrender, or someone unconscious or too incapacitated by injury or sickness to defend themselves. The protection is subject to conditions: the person must refrain from hostile acts and must not attempt to escape.
Recognising when someone is out of action often depends on visible signs, such as raised hands, a dropped weapon or physical collapse. Neurotechnology could make those signs harder to read. Three hypothetical scenarios illustrate the difficulty.
When incapacity is invisible
Conventional weapons may leave visible injuries. A weapon designed to disrupt brain function could instead leave someone standing and apparently unharmed, but unable to think clearly or defend themselves.
An attacker might fail to recognise that incapacity and continue firing. Whether the attack would be lawful would depend on the circumstances, including what the attacker knew or should have recognised. The practical challenge is how to protect someone whose incapacity cannot readily be seen.
When the equipment keeps fighting
Brain–computer interfaces (BCIs) connect brain activity to external devices. Imagine a soldier using such an interface alongside a powered exoskeleton: a wearable mechanical system that supports or enhances movement. If the soldier became unconscious, an automated system might continue to return fire or move them away from danger.
The person could be helpless while their equipment remained a threat. How should the law distinguish between the two? And what protection should the person receive when they can no longer control what the system does?
When a soldier cannot signal surrender
A soldier usually communicates surrender through words or gestures. But suppose a neural interface designed to suppress fear or override hesitation also interfered with their ability to raise their hands or otherwise signal surrender.
The soldier might want to stop fighting but be unable to make that clear. An adversary could continue to regard them as a threat. One possible response might be a digital surrender signal or a mechanism that disables the equipment and alerts the opposing force. How such a system could operate reliably, and what legal significance its signal should have, remain open questions.
2 When treatment becomes a military capability
The boundary between medical treatment and military enhancement is not always clear. A technology’s purpose can change gradually:
Treatment: BCIs, brain stimulation and monitoring tools are being developed to treat brain injury, restore communication and help manage conditions such as post-traumatic stress disorder (PTSD).
Prevention: Similar tools may help healthy personnel monitor fatigue, manage stress and avoid accidents.
Performance: The same technology may then be adapted to improve reaction times, help drone pilots manage information overload or connect people more closely to military equipment.
Countries bound by Additional Protocol I to the Geneva Conventions must assess whether new weapons or ways of conducting warfare would be prohibited by international law. A technology developed for medical treatment may also require this assessment if it is adapted for military use.
The difficulty is recognising when and how its use has changed. A system introduced to help an injured soldier communicate may raise different questions when adapted to support targeting decisions. Review processes need to keep pace with those changes, including uses of equipment that is not itself labelled a weapon.
3 Where medical care ends and enhancement begins
Medical personnel receive special protection under the laws of war. Article 24 of the First Geneva Convention protects personnel exclusively engaged in specified medical duties, including treating the wounded and sick. Article 43 of Additional Protocol I also excludes the medical personnel it covers from combatant status.
What happens if a medic uses neurotechnology to increase a soldier’s aggression? There is an argument that this role may fall outside the protection given to medical work. Much would depend on what the medic was doing and how the relevant rules applied.
Reducing fear is not necessarily the same as increasing aggression. Treatment that helps someone manage excessive fear or emotional overload may improve their judgement and ability to follow the laws of war. That makes the boundary between care and enhancement particularly important.
How could treatment and military enhancement be distinguished in practice?
What happens when the same medic performs both roles at different times?
Should armed forces keep those roles separate?
These are questions about the purpose and effects of an intervention, rather than simply whether it uses neurotechnology.
4 Who is responsible when a system acts before conscious choice
Criminal responsibility generally depends on both what a person did and their state of mind at the time. Lawyers call these actus reus and mens rea. The mental element required varies with the offence, but may involve intention or knowledge.
Neurotechnology could complicate that relationship by allowing a system to respond to brain activity before the person is consciously aware of it.
A weapon fires before the soldier decides
Imagine a system that detects a soldier’s brain response to a possible threat and fires before they have made a conscious choice. Asking “What did the soldier intend when they fired?” becomes much more difficult.
There could be an argument that the soldier lacked the state of mind needed for the particular offence. Earlier decisions, training and the way the system worked would still matter. The answer cannot be assumed from the speed of the response alone.
The emotional consequences may also be very different from the legal position. A soldier could experience profound guilt or distress about what happened even where their legal responsibility is uncertain.
Could the commander be responsible
Commanders can be held responsible for failures to prevent or respond to crimes by forces under their control. Article 28 of the Rome Statute sets out the relevant requirements. For military commanders, these include whether they knew, or should have known, that their forces were committing or about to commit crimes, and whether they failed to take the necessary and reasonable measures available to them.
A commander cannot realistically interrupt a response happening inside a soldier’s brain in milliseconds. But that does not end the inquiry into responsibility. If software misreads brain signals under stress, attention may also turn to the people who designed, tested or procured the system.
Different forms of responsibility could arise. A claim for compensation over a defective product is different from a criminal prosecution for a war crime. A design fault would not, by itself, resolve whether anyone in the chain of command also bore responsibility.
Responsibility for the decision to deploy
One possible approach is to look at the earlier decision to put the system into use. Did the commander know, or should they have known, that it would produce actions no person could meaningfully oversee? Had the system undergone an adequate legal review?
That decision could potentially provide a basis for responsibility, even if the commander could not stop an individual firing. Whether existing law can accommodate this approach, or would need further development, remains uncertain.
5 Treating traumatic memories while preserving accountability
Memory modulation techniques aim to change aspects of memory through interventions such as medicines or brain stimulation. Depending on the technique, they might reduce a memory’s emotional intensity, alter how it is recalled or potentially erase it. Relieving the distress associated with a memory is not the same as removing the memory itself.
Losing the memory of an offence does not, by itself, remove criminal responsibility. It does, however, raise difficult questions about evidence, identity and the purpose of punishment. There are also questions about how survivors can receive treatment without losing testimony that may be important to justice.
Whose interests | Possible effect | The question |
The person accused | They may no longer remember the alleged offence. | How should changed memories affect the assessment of evidence and the purpose of punishment? |
Victims seeking justice | A perpetrator’s recollections may be lost. | Could treatment make it harder to establish what happened or be misused to conceal wrongdoing? |
Survivors and the wider community | Treatment may alter survivors’ memories of events. | How can people receive care while preserving reliable testimony and a record of atrocities? |
In his 2025 article “Can you forget a war crime?”, published in AJOB Neuroscience, Benjamin Gregg proposes that traumatic memories may be softened to relieve suffering, subject to safeguards. These include preserving a person’s understanding of their own history, their ability to make moral sense of events and give reliable evidence, their voluntary consent, and the possibility of establishing what happened and who was responsible.
The aim is to support recovery while preserving accountability. Achieving both may be difficult, particularly if the military or state controls the treatment. How can safeguards distinguish genuine therapeutic relief from an intervention that conveniently removes evidence? The difficulty calls for careful safeguards and oversight, while leaving room for treatment that could relieve serious suffering.
Preserving independent human judgement
Fear, hesitation and doubt can give a soldier time to question a decision, distinguish a civilian from a combatant or exercise restraint. Excessive fear can also narrow attention, impair judgement and lead to impulsive reactions. Neurotechnology that reduces panic could therefore help personnel act lawfully.
The question is how an intervention affects the ability to make an independent judgement before using force. Does it help someone think clearly under pressure, or remove the hesitation that might have stopped a wrongful act?
As neurotechnology brings the brain and military equipment closer together, these questions will become increasingly important. The challenge is to preserve protection and accountability while recognising that some of the same technologies may also improve care, safety and decision-making.
