The tragic shooting down of the Ukrainian airliner over Tehran last week, which Iran has admitted to after several days of denial, has led me to think about a set of issues that was already on my mind when we were discussing the legality of the US strike on Soleimani. How exactly does international law deal with situations in which state agents use lethal force and do so under the influence of a mistake or error of fact? For example, when an Iranian air defence officer shoots down a civilian airplane thinking that he was shooting down an American cruise missile; or, when a state uses force against another state thinking, on the basis of imperfect intelligence information, that is the victim of an ongoing or imminent armed attack, and it later turns out that there was no such attack. Does international law provided reasonably consistent, coherent and fair rules to address such situations? To what extent can we generalize about such rules, and to what extent are they fragmented and context-specific?
Domestic legal systems have long dealt with such issues. Perhaps the most common such scenario – in some countries all too common – is the use of lethal force by the police against a person whom the officer concerned mistakenly believed was posing a threat to others, but who in fact posed no such threat.
Most domestic systems that I am familiar with have mistake of fact rules or doctrines in their criminal laws. Such rules, whether grounded in statute or in case law, often distinguish between honest mistakes, based purely on the subjective belief of the person using force, and reasonable mistakes, assessed on the basis of some kind of objective standard of behaviour. In most domestic systems mistake of fact can preclude criminal liability in some circumstances, and mitigate punishment in others. But municipal laws are rarely as clear with regard to civil, delictual responsibility in tort, which is the closer analogue to state responsibility in international law.
I can’t claim to have done genuinely comprehensive research on this topic, but it seems to me that there is a significant gap here in the international legal literature. How exactly do we handle mistakes of fact in the various different sub-fields of international law, especially when the mistake involves uses of lethal force? And are we content that whatever solutions we have come up with are the right ones?
This three-part series of posts is not even an attempt at filling this gap – think of it more as a conversation starter. I would be most grateful to readers for additional examples in the comments or for any other thoughts they might have. In this first post, I will briefly examine how mistakes of fact in using lethal force are addressed in international criminal law, international humanitarian law, and international human rights law. My second post will look at mistakes of fact in self-defence under the law on the use of force (jus ad bellum), examining as a case study the 1988 downing of Iran Air Flight 655 by the USS Vincennes. The third and final post will then offer some conclusions and some tentative thoughts on the downing of Ukraine International Airlines Flight 752 over Tehran.