Professional conduct is the body of legal, ethical and doctrinal rules that distinguish a legitimate combatant from a criminal. It is not etiquette: it is the condition that protects the operator from criminal jurisdiction, the unit from delegitimisation, and civilians from avoidable consequences of combat. The international volunteer is subject to it as is any regular soldier.
International law of armed conflict
The Geneva Conventions (1949) and Additional Protocols (1977) define the binding rules for anyone participating in hostilities. The cardinal principles: distinction (between combatants and non-combatants), proportionality (military gain vs collateral damage), precaution (reasonable measures to limit damage), humanity (prohibition of unnecessary suffering). They are not options: they are positive law.
- Distinction: fire is directed at combatants, not at civilians or civilian objects
- Proportionality: expected civilian harm must not be excessive relative to military advantage
- Precaution: target identification, choice of means, warning where possible
- Humanity: no weapons producing unnecessary suffering, no cruel treatment
- Legal status: regular combatant, irregular combatant, civilian — the three categories carry different protections
An international volunteer integrated into the Armed Forces of Ukraine (contract, uniform, chain of command) holds regular combatant status and enjoys PoW protections. A non-integrated volunteer, in civilian clothes, may be classified as 'mercenary' or 'unlawful combatant' without the same protections. The difference is legal and has consequences on capture.
Rules of Engagement (ROE)
ROE are the specific rules, issued by command, that define when fire may be opened. They are more restrictive than international law: what is legally permissible may be forbidden by ROE for political, operational or propaganda reasons. Knowing the ROE is mandatory. Violating them is a disciplinary offence and potentially criminal.
- Positive identification (PID) — see and classify before firing
- Declared Hostile — target authorised by default
- Hostile Act — fire on friendlies authorises response
- Hostile Intent — manoeuvre indicating preparation of hostile act
- Property defence — generally not enough for lethal force
- Geographic, temporal, weapon-type constraints — vary by mission
Typical ROE in a Ukrainian LOC area: PID mandatory, fire authorised on armed personnel moving toward friendlies, fire not authorised on civilians fleeing even from enemy positions, artillery fire limited to coordinates validated by at least two sources. Variations by area and operational phase.
Civilian interaction
Civilians in a combat area are vulnerable subjects and simultaneously sources of information, operational risk, propaganda leverage. Correct conduct is: do not open fire absent a clear hostile act; do not interrogate aggressively; do not occupy private property without need; document significant interactions.
- Never fire on fleeing civilians, even from enemy-controlled areas
- Never use civilians as human shields or for unprotected scouting
- Never requisition goods without authorisation and without receipt
- Never enter personal or sexual relationships with local population during operations
- Identify child soldiers or civilian spotters — non-lethal neutralisation where possible
- Document in photo/video incidents involving civilians (for future legal protection)
Prisoners of war
Capturing a prisoner is a high-risk event legally, operationally and reputationally. Geneva Convention III rules are non-derogable: humane treatment, no torture interrogations, no public exposure, no execution. Handling procedures summarise in the 5S mnemonic: Search, Silence, Segregate, Safeguard, Speed.
- Search: full pat-down, seize weapons, documents, gear
- Silence: the prisoner does not talk to other prisoners (prevent coordination)
- Segregate: separate by rank and role (officers from troops)
- Safeguard: protect from harm (fire, cold, hunger, thirst, exposure)
- Speed: rapid evacuation to higher echelon (professional interrogation)
Never summary execution. Never torture. Never humiliating photo/video distributed. Never trophies (ears, badges from body). Never interrogation under threat of death. Never handover to unauthorised units. Violating any of these exposes to international criminal prosecution and destroys the reputation of your unit.
Documentation and audit
Professional conduct requires traceability. Fire-opening decisions, civilian interactions, prisoner handling must be documented coherently with the host unit's protocols. Correct documentation protects the operator against later accusation and supports the unit's legitimacy.
- Keep a temporal log of significant events (times, coordinates, people present)
- Preserve written and radio orders (recordings or transcripts)
- Report incidents to command immediately, do not wait for debrief
- Do not destroy potentially compromising documentation — supports your case if honest
- Cooperate with internal investigations — opacity increases suspicion
Common mistakes
- Treating international law as a recommendation rather than a binding rule
- Confusing 'what the Russians do' with the criterion for your own conduct — it is not
- Treating civilians as hostile by default in contested zones
- Publishing photos of prisoners or corpses on open channels
- Accepting blatantly illegal orders without formal objection
- Failing to document incidents for fear of consequences — absence of documentation is itself suspect
Lessons learned Ukraine
International volunteers in Ukraine are particularly vulnerable to criminal prosecution in their home countries on return. Publishing enemy corpse photos, publishing prisoner interrogations, taking part in operations targeting civilians — all this is prosecutable in EU and North American states regardless of theatre. Professional conduct is not only ethical: it is legal self-protection. A volunteer returning home with compromising videos on the phone becomes a defendant.