The prohibition on attacking a person recognised as hors de combat is a rule of customary international humanitarian law, reflected in Rule 47 of the ICRC Customary IHL Study and historically expressed in Article 23(c) of the Hague Regulations of 1907. It binds all parties to an armed conflict irrespective of treaty ratification. The prohibition protects the person who has surrendered or is otherwise hors de combat; its practical operation presupposes that an intention to surrender, where it arises, can be expressed, perceived, and translated into the withholding of attack before force becomes irreversible. Where a system is intended for use against persons in circumstances in which surrender is reasonably foreseeable, compliance cannot safely depend on an operational process that affords no practical means for a surrender indication to affect the engagement before that point. The protected status may arise; the operational process may nonetheless remain incapable of responding to it in time. That incapacity is not a circumstance encountered in the field. It is established in advance, by design.
For States party to Additional Protocol I, Article 41 provides the clearest treaty formulation of the prohibition and contains an internal standard of recognisability: protection attaches not only to actual recognition but to what, in the circumstances, should be recognised. Article 57 supplies relevant precautionary obligations, including the duty to cancel or suspend an attack when it becomes apparent that the objective is not a military one or is subject to special protection. Article 36 provides the procedure through which the question must be examined at the stage of study, development, acquisition or adoption. For non-party States, the substantive customary obligations remain applicable; whether and through which formal procedure the corresponding system risk is reviewed depends on the State's national law, weapons-review policy, procurement framework or military directives. Customary precautionary duties remain relevant to the substantive assessment but are not treated here as creating a universal Article 36-equivalent procedure.
This paper argues that surrender-recognition capability, understood as the preservation of a recognition window, is not a new obligation but a condition of effectiveness of obligations that have bound parties for over a century. The recognition window is an analytical and testable measure of whether the operational process affords sufficient time for a surrender indication, where one arises, to affect the engagement before force becomes irreversible; the paper does not treat that interval as an independently established rule of customary law. It advances a specific proposition: where the foreseeable normal use of a system would engage persons who, in the circumstances, should be recognised as hors de combat, review must examine whether the system preserves the practical possibility of compliance; and the systematic exclusion of technically achievable safeguards relevant to that question warrants documented justification rather than silence.
International Humanitarian Law · Autonomous Weapons · AI Governance · Lawful Operational Safeguards · Surrender Recognition · Meaningful Human Control · Temporal Compression · Defence Procurement · IHL Compliance Architecture · Article 36 AP I · Article 41 AP I · Article 57 AP I
The temporal structure analysed in this paper is not unique to IHL. For the parallel argument in civil machine-safety law, see: Systemic Arrestability: Operator Protection in Machine Safety Law When Machine Speed Exceeds Human Reaction (Paper II, 2026), Zenodo DOI 10.5281/zenodo.20837150.
The feasibility criteria developed here are applied to a candidate recognition protocol in HF SIGNAL 01 (Paper III, 2026), Zenodo DOI 10.5281/zenodo.21183137, and extended in the HFA Technical Note series.