International humanitarian law applied to cyber-warfare : precautions, proportionality and the notion of "attack" under the humanitarian law of armed conflict
Terry D. Gill
Research handbook on international law and cyberspace
Cheltenham ; Northampton : Edward Elgar, 2015
This chapter examines the application of the principle of proportionality and the duty to take precautions in attack in relation to attacks carried out in the cyber domain. Terry Gill argues that a cyber attack would only qualify as an "attack" for the purpose of international humanitarian law if it is committed in the context of a recognised armed conflict and is intended to or reasonably likely to cause appreciable danger of physical harm or damage. He concludes that while many cyber attacks would therefore not qualify as attacks, some would and, for those, international humanitarian law would be applicable by analogy in much the same way as it applies to attacks by kinetic weapons. Thus, cyber attacks against purely military installations or combatants, without any likely appreciable consequences to civilians or civilian objects, would fall outside the applicability of proportionality. Cyber attacks directed against military objectives or combatants that incidentally harm civilian objects or civilians are subject to the proportionality test and would be unlawful if the expected damage to the civilian objects or civilians is likely to be excessive in relation to the anticipated military advantage.