Counterterrorism measures outside of the battlefields of the Non-International Armed Conflicts, shall be governed by the law enforcement model, rather than the law of armed conflict.
Hostilities that do not reach the threshold for an armed conflict are not to be ruled under International Humanitarian Law, but rather under the law enforcement model and human rights law. The possibility of using targeted killings as a counterterrorism measure under the law enforcement model is more limited than under the law of armed conflict. For a state to justify the targeted killings outside the war paradigm, it must show that an operation is lawful under the domestic law of homicide, as well as human rights law, and that they are carried out with respect for the sovereignty of other states.
Normally, a suspected criminal must impose an immediate and lethal threat in order for a law enforcement officer to be allowed to fire arms at him. However, such an officer may fire arms at a suspect even where such threat is lacking if he believes the suspect might cause serious physical harm. Although it may be legal for a law enforcement officer to kill a suspect posing an immediate threat, he stresses that the goal of a law enforcement operation always should be not to kill. International Human Rights Law allows the use of lethal force against individuals threatening the security of a state, as long as all other measures to arrest the suspect are exhausted and the operation is preemptive rather than retributive.
DISCUSSION PAPER 2: DRONE ATTACKS, INTERNATIONAL LAW, AND THE RECORDING OF CIVILIAN CASUALTIES OF ARMED CONFLICT, pp. 9-10