I am glad that Marko has taken on the task of tackling the issue of mistakes of fact in international law, as I completely agree that it is a very important yet so far largely overlooked aspect, surprisingly so. While I’d mostly approve of Marko’s deliberations and conclusions, I wanted to add a brief point that I came across while doing research for my soon-to-be-published book on remedies in cyberspace that might be suitable to further inform this important debate. Given the technical features of cyber infrastructures, the issue of mistakes of fact in relation to measures taken in self-defence is even more critical in this context.
This is because a state might of course not only factually err in regard to the existence of an armed attack pursuant to Article 51 UN Charter, but just as well in relation to its author. This issue has come up more recently in connection with armed attacks in or through cyberspace and the widely discussed attribution problem. An imminent crisis caused by a cybersecurity incident as the result of a malicious cyber operation that indeed leaves “no choice of means, and no moment of deliberation” is easily imaginable. At the same time, given the persistent difficulty to identify an operation’s source and agent with reasonable certainty reasonably fast, it is equally easily imaginable that mistakes will happen – leading to a forceful response in putative self-defence against the wrong target (for instance a critical server in an uninvolved third country that had been employed in order to carry out the malicious operation). What should be the legal consequences of such a mistake of fact?