[Jens David Ohlin is Professor of Law at Cornell Law School.]
Ian Henderson and Bryan Cavanagh have hit the nail on the head in identifying a crucial and under-theorized question that goes right to the basic structure of the laws of war. I am in complete agreement that invocations of self-defense during armed conflict are both confused and confusing.
There is already the frequent problem of conflating individual self-defense (in the criminal law sense) with collective self-defense (jus ad bellum and article 51 of the UN Charter). In addition, one often hears talk of a soldier’s right of self-defense – a claim that is mostly redundant since soldiers hold the privilege of combatancy and have no need to invoke a separate justification for their behavior. A justification like self-defense serves to negate the wrongdoing of the act, but a privileged soldier who kills a legitimate target has committed no wrongful act that requires negating. Consequently, the justification of self-defense is only relevant during armed conflict when the defender is unprivileged, such as a civilian who has no right to participate in armed conflict. If the civilian is challenged by an enemy combatant who refuses to obey the principle of distinction, then the civilian is entitled to kill the soldier in self-defense. If a soldier is attacked by a civilian, the soldier can legitimately kill the civilian because he is directly participating in hostilities; no claim of self-defense is required because the privilege applies.
Understanding self-defense from a civilian’s perspective is more difficult. Consider the complicated problem of a civilian who kills an enemy soldier who is in the process of killing the civilian as collateral damage during a lawful attack against a military objective. In that scenario, does the civilian have the right of self-defense? In the criminal law we usually view the right of self-defense as only applicable against unlawful attacks, but in this case the attacking soldier’s original assault is lawful under LOAC as long as the anticipated collateral damage is not disproportionate to the value of the military objective. If the envisioned collateral damage is disproportionate, then the attack is unlawful. So, in that case, the right of the civilian to exercise self-defense would depend entirely on the civilian making the correct assessment of not only the collateral damage, but also the anticipated collateral damage viewed -- not from his perspective – but rather from the perspective of the person attacking him! A greater conceptual riddle I cannot fathom. This would be a nightmare for a criminal court, international or domestic, to adjudicate.
The deeper issue imbedded in Henderson and Cavanaugh’s research is the application of the privilege of combatancy to non-international armed conflicts. The standard textbook answer is that the privilege is inapplicable to NIAC because the very concept of “combatant” is part of the legal architecture of IAC. Under this view, a NIAC can only have government forces and rebels – never combatants per se.
To my mind, this statement is often reflexively repeated in the literature without due consideration for whether it is always and universally true. Few individuals have challenged it, though Henderson himself is one of the few to have seriously studied the issue, writing
articles suggesting that government forces in NIACs are privileged belligerents and that prosecuting them domestically would violate the laws of war. Henderson is to be commended for tackling an understudied but vital topic.
