According to the Inter-American Commission on Human Rights in its Report on Terrorism and Human Rights 2002, it is possible to use lethal force against suspected terrorists under a law enforcement model. It states that: in situations where a state's population is threatened by violence, the state has the right and obligation to protect the population against such threats and in so doing may use lethal force in certain situations.
The Inter-American Commission on Human Rights Report on Terrorism and Human Rights provides that states must not use force against individuals who no longer present a threat as described above, such as individuals who have been apprehended by authorities, have surrendered or who are wounded and abstain from hostile acts. It is also a general principle of international law that a State is strictly prohibited from engaging in law enforcement operations in the territory of another State, especially when the operation, like drone attacks, includes the use of lethal force. An important difference between the law of armed conflict and the law enforcement model is that while the former requires civilian casualties to be proportional to the military advantage gained, the latter generally does not accept any casualties of innocent bystanders at all. This means that if there are civilian casualties, together with a high al-Qaeda operative, this may be regarded as proportional under the laws of war – is an unlawful killing under the law enforcement model.
DISCUSSION PAPER 2: DRONE ATTACKS, INTERNATIONAL LAW, AND THE RECORDING OF CIVILIAN CASUALTIES OF ARMED CONFLICT, pp. 10-11