The majority of US drone strikes are now based on Signature Drone Strike Protocol (SDSP). The theory behind these signature strikes is that an individual’s pattern of behaviour, their “signature”, serves as a proxy for determining if that individual has either a ‘continuous combat function’ (and is therefore a lawful target), or,
alternatively, is a civilian ‘directly participating in hostilities’. The general rule is that an individual combatant may be targeted with lethal force under international
humanitarian law. The difficulty with SDSP, however, is that it does not sit easily with the accepted definitions of ‘continuous combat function’ or ‘directly
participating in hostilities’.
Certainly, comments by US officials indicate that drone operators may be instructed to assume that all military-age males in a potential strike zone are combatants unless there is explicit evidence to the contrary.141 In the leaked DOJ White Paper, the Administration argued for an expanded definition of “imminent” danger,142 primarily based on its argument that an individual directly participates in hostilities simply by virtue of membership of Al-Qaeda or an associated group, and that defining the scope of ‘direct participation’ in this manner allows the US to, “avoid broader harm to civilians and civilian objects.”143 Some counter-terrorism officials have insisted that an individual in an area of known terrorist activity is most likely participating in such activities, especially if in close proximity to a senior Al-Qaeda member, and is therefore a legitimate target for a signature strike: “Al-Qaeda is an insular, paranoid organisation – innocent neighbours do not hitchhike rides in the back of trucks headed for the border with guns and bombs.”144
141 See Chris Woods, ‘Analysis: Obama Embraced Redefinition of ‘Civilian’ in Drone Wars’, Bureau of Investigative Journalism, 29th May 2012, available at
http://www.thebureauinvestigates.com/2012/05/29/analysis-how-obama-changed-definition-of- civilian-in-secret-drone-wars/, (accessed 14th July 2015).
142 See Department of Justice White Paper, ‘Lawfulness of a Lethal Operation Directed Against a U.S. Citizen Who is a Senior Operational Leader of Al-Qaeda or An Associated Force’, supra n.73, at 8. 143 See R. Vogel, ‘Drone Warfare and the Law of Armed Conflict’, 39 Denv. J. Int’l L & Pol’y 101 (2011), at 121.
It is respectfully submitted that targeting on the basis of such assumptions may violate international humanitarian law. As Melzer rightly notes, even in the context of a ‘war on terror’, or a war against specific terrorists, individuals do not become legitimate targets simply by membership of a terrorist group or by physical association with, or proximity to, members of such a group.145 Individuals can only become legitimate targets on the basis of their roles within such groups as determined by their actual activities.146 Thus, within the context of international humanitarian law, the term ‘combatant’ must refer only to members participating in armed hostilities, and
combatant status cannot be established on the basis of affiliations, family ties, or mere association.147 There must be an act, and that act must contribute to a continuous role within the armed group. Therefore, the insistence of the Obama Administration that a person in physical proximity to terrorists is more likely than not to be a terrorist too, is not necessarily compliant with the principle of distinction.
There is, regrettably, little information in the public domain as to what types of
behaviour are sufficiently suspicious to merit a signature drone strike. However, it can be inferred from the various information leaks and investigative reporting that the “signature” of a potential target is defined very broadly. The difficulty, however, is that in some communities, there may be little significant difference between the day- to-day behaviour of a civilian and that of a terrorist, as perceived by a drone operator. For example, it is a well-accepted fact that in some strike zones, terrorists regularly intermingle with the civilian population, and do not wear uniforms or other
distinguishing markers setting them apart from civilians.148 In consequence of this, drone operators have conflated otherwise normal behaviour with suspicious behaviour on several occasions, targeting people who were carrying weapons, or who were present in a location mistakenly identified as a terrorist compound, or who were travelling in a convoy of vehicles.149 Individuals have also been targeted for driving a suspicious vehicle, for spending time in and around certain facilities, and for
operating certain types of communication equipment.150
145 See Interpretive Guidance, supra n.122, at 44. 146 See ibid.
147 See ibid, at 33.
148 See ‘Living Under Drones: Death, Injury, and Trauma to Civilians from U.S. Drone Practices in Pakistan’, supra n.29, at 112.
149 See ibid. 150 See ibid.
The fact that Al-Qaeda and Taliban fighters have adopted the tactic of mingling regularly with the civilian population certainly poses challenges for drone operators and military commanders. However, this tactic is no justification for the adoption of a broad ‘pattern-of-life’ analysis with a wide scope of activities listed as suspicious “signatures”. International humanitarian law requires that militaries engaged in armed conflict must always attempt to distinguish between civilians and combatants.151 The United States cannot simply circumvent this requirement by adopting a broadly defined Signature Drone Strike Protocol, in which a wide scope of activities are listed as suspicious “signatures”, exposing individuals to the possibility of targeting by lethal force. Given the broad scope of suspicious “signatures”, as well as the
expanded concept of “imminence” favoured by the US Administration, which exposes individuals to lethal force on the basis of membership of Al-Qaeda or associated forces, SDSP stands as a poor proxy for the concepts of ‘direct participation’ and ‘continuous combat function’. Not only does SDSP constitute a prima facie violation of the duty placed upon the United States by international humanitarian law to distinguish between civilians and combatants, but also, as shall be evidenced, the mandate to exercise proportionality in the execution of lethal force.