When should International Humanitarian Law (IHL) prevail over, when give way to International Human Rights Law (IHRL)? IHL and IHRL give diverging answers to the crucial question of when it is permissible to kill during an armed confrontation. This paper contends that when two bodies of law make diverging substantive demands – as IHRL and IHL do – that which better discharges the law’s moral tasks should displace the other. The law’s two moral tasks, the paper argues, are to guide its subjects’ conduct, as often as possible, towards the course of action that conforms to their moral obligations (task one) and to secure the fullest feasible protection of rights in the outcome of conduct (task two).
IHL permits conduct that further diverges from our fundamental moral obligations of non-interference with the individual right to life. Yet, the law that more faithfully reflects underlying moral principles is not always the law that better discharges its moral tasks. Epistemic barriers to identifying the morally right course of action account for why a law that further diverges from moral principles might better guide the individual towards what is typically the morally right course of action (task one). Volitional defects may mean that a law that asks for a course of action other than the morally right one, generates better aggregate moral consequences (task two). Whether IHRL or IHL should prevail, depends on the epistemic and volitional context of decision-making during the conduct of hostilities.
The paper raises the question of whether IHL or IHRL should govern the conduct of hostilities for six types of non-international and international armed conflicts (NIACs and IACs). One of two characteristics distinguishes them from confrontations that do not count as armed conflicts: either the intensity of hostilities or a state’s (non-authorised) use of armed force outside its own territory. The paper analyses how the intensity and territorial scope of hostilities affect the epistemic and volitional context of decision-making on the battlefield and thereby IHRL’s and IHL’s respective ability to discharge the law’s two moral tasks.
This analysis leads to the following proposal for a moral division of labour between IHRL and IHL: As the morally prima facie better law IHRL should govern the conduct of hostilities in law enforcement operations. In non-protracted IACs, ‘symmetrical IHRL’ – applied as if both parties had a lawful aim - should govern the permissibility of killing. Above the threshold of intensity at which hostilities count as protracted, hence during NIACs and protracted IACs, we face a choice between affording individuals a guide towards what is typically the course of action that conforms to their moral obligations (task one) and reducing individual rights violations in the outcome of warfare (task two). ‘Symmetrical IHRL’ better discharges task one; IHL better discharges task two. It depends on the relative moral costs of prioritizing one task over the other, which body of law should prevail. I argue that IHL currently offers a better, but far from morally ideal law for governing the permissibility of killing during the conduct of hostilities, once these hostilities reach the crucial threshold of being protracted. From a moral point of view, IHL should therefore displace IHRL and govern, on its own, the conduct of hostilities during NIACs and protracted IACs.
