Proportionality and Civilian Use of a Military Objective

[Ori Pomson is a member of the Israel Bar and currently an LLM candidate at the Hebrew University of Jerusalem. Previously, he served for six years as an officer (rank of captain) in the Israel Defence Forces Military Advocate General’s Corps International Law Department, where he served as Assistant Legal Adviser for Cyber Affairs and Assistant Head of the Legal Development Section.]

I. Introduction

One of the subjects which has been the focus of legal discussion in the context of the latest round of hostilities in the Israeli-Palestinian conflict is the proportionality of certain attacks under international humanitarian law (IHL). While it would appear that many of the disagreements on the legality of certain attacks concern factual controversies, one legal question which has been the centre of attention is that of whether a rule of proportionality is applicable to damage caused to a structure which serves both military and civilian functions. Respective posts by Aurel Sari and Michael Schmitt at Articles of War, as well as respective posts by Adil Haque and Brian Cox at Just Security, have addressed this issue in the context of broader analyses of the legality of strikes on tall buildings. As the issue has received different response, the present post seeks to look into the particular proportionality question in greater detail, focusing solely – and doctrinally – on its legal aspects.

Now, it is possible to broadly divide the question of proportionality and structures with military and civilian functions into two separate questions, each arising in different circumstances and necessitating somewhat different analyses. The first concerns a structure which, as a whole, is used for both civilian and military purposes. A classic example in this regard is a power plant which supplies electricity to a military base and civilians; must the military commander, under international law, before attacking the building, consider whether the expected damage to the civilian use of the power plant renders the incidental harm excessive to the anticipated military advantage deriving from the attack?

The second circumstance concerns a structure where different components thereof are being used for different purposes. For example, if an apartment building, which includes numerous housing units, also contains a command and control centre used by the armed forces of a party to an armed conflict, must the military commander upon conducting an attack factor in the expected damage to the civilian components thereof?

A related issue concerns instances in which a moveable civilian object is located inside a military objective; for instance, if a military general keeps an antique collection in his or her office, must the antiques be considered in the military commander’s proportionality assessment? This is an issue which, while of importance, has been less the focus of discussion, and hence for reasons of space it will suffice to note that it has received contrasting answers (cf Denmark Manual; ILA CoH Study Group).

This post will analyse the first two questions mentioned. It will first address these two questions of civilian use and proportionality through interpreting the relevant rules in the First Additional Protocol to the Geneva Conventions (API), which is applicable to relations between the parties thereto in international armed conflicts as defined therein. It will then proceed to consider these two question from the perspective of customary international law, which is applicable in the relations of non-parties to API, as well as in non-international armed conflicts.

II. Interpreting API

Like any question on the substance of a treaty obligation, recourse should be made to the customary rules on treaty interpretation, codified in articles 31-33 of the Vienna Convention on the Law of Treaties (VCLT) (Alleged Violations, ¶35). In particular, article 31(1) of the VCLT provides that ‘[a] treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose’. As the International Court of Justice has recently recalled, under this rule, ‘[i]nterpretation must be based above all upon the text of the treaty’ (Qatar v UAE, ¶81).

The rule relating to proportionality is mentioned three times in API – in articles 51(5)(b) and 57(2)(a)(iii) and (b). Under these three provisions, a disproportionate attack is one ‘which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated’. Thus, on the civilian side of the proportionality equation, regarding harm to non-human things, the military commander is obligated to consider ‘damage to civilian objects’.

What are civilian objects? Article 52(1) of API provides that ‘[c]ivilian objects are all objects which are not military objectives’, whereas article 52(2) of API defines the latter as ‘limited to those objects which by their nature, location, purpose or use make an effective contribution to military action and whose total or partial destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage’. It follows that, for an object to be excluded from a proportionality assessment, it must constitute a ‘military objective’. Moreover, the distinction is binary – an object is either a civilian object or a military objective.

It would appear uncontroversial that when an entire structure, like a power plant, is being used for military purposes it fulfils the requirements of a military objective. It follows that it is a military objective – not a civilian object, despite is simultaneous civilian use – and hence damage thereto need not be considered in a proportionality assessment under API.

The issue of a single structure where different components thereof are used for the different functions is somewhat more complex. Is the structure one military objective, thereby not falling within the obligatory proportionality equation? Or, are its components separate objects, some of which civilian objects and thus part of the obligatory proportionality equation? It appears other provisions in API – the ‘context’ – are of assistance in this regard. Article 51(5)(a) provides that under the category of ‘indiscriminate attacks’ is an attack which ‘by bombardment by any methods or means [] treats as a single military objective a number of clearly separated and distinct military objectives located in a city, town, village or other area containing a similar concentration of civilians or civilian objects’. Considering ‘military objectives’ in this contexts are ‘objects’, it would appear to be implied that the delineation of an object depends on whether it is ‘clearly separated and distinct’ – something which is clearly not the case regarding a single structure (see Aurel Sari’s analysis in this regard). To buttress this understanding, one may also have reference to article 52(3), which considers ‘a place of worship, a house or other dwelling or a school’, respectively, as objects in the singular, despite these often including numerous units. As the entire structure constitutes a military objective, it need not be included in a proportionality assessment.

It does not appear reference to API’s object and purpose would change this understanding due the latter’s modest role in treaty interpretation (Yasseen, 57); the precedence given to the text of the treaty in the interpretative exercise (see Guinea Bissau v Senegal, ¶56); and in light of the API’s purpose essentially being one of striking a balance between humanitarian protection and the military exigencies (developed further here at 14-15).

III. Customary IHL

Like all questions of customary international law, and as the International Law Commission uncontroversially – at least for states – stated, ‘[t]o determine the existence and content of a rule of customary international law, it is necessary to ascertain whether there is a general practice that is accepted as law (opinio juris)’. In the absence of one of these elements regarding a certain matter, the existence of a customary rule obligating a certain form of conduct on the matter cannot exist.

The lack of opinio juris supporting the position that there is an obligation to consider damage to the civilian use of structures which serve both military and civilian functions is apparent. To begin with, parties and non-parties to API often formulate the proportionality test in other contexts in very similar terms to that which appears in API (eg, Azerbaijan; Brazil; Croatia; Cuba; Israel; Serbia; Turkey; United States). That they state that it is damage to civilian objects which is to be considered should be taken as the term is understood in the ‘treaties which they conclude’ (see also in this regard CCW, Protocol II art 2 and Protocol III art 1) and ‘in the practice of States’ (Spain v Canada, ¶70). One state – Denmark (195, 708) – has also made explicit its absence of opinio juris regarding the inclusion of damage to the civilian function of a military objective, whereas another state – Norway (¶2.22) – though far from clear terms, may have enunciated opinio juris in favour of the existence of such an obligation. One state (potentially) supporting the proposition that damage to the civilian function of a military objective is manifestly very distant from the necessary quantum for a customary rule to develop. In the absence of an opinio juris in favour for such an obligation, the conclusion that follows is that the civilian use of a single structure which constitutes a military objective need not be considered in a proportionality assessment.

Now, it appears certain scholars have referred to statements in military manuals relating to proportionality in the context of attacking so-called ‘dual-use’ infrastructure in arguing that civilian use of such infrastructure must be considered in a proportionality assessment. In particular, reference (see ICRC report, 38) has been made to the United States Armed Forces Joint Publication 3-60 (A-5), which states that:

If the attack is directed against dual-use objects that are legitimate military targets but also serve a legitimate civilian need (e.g., electrical power or telecommunications), then this factor must be carefully balanced against the military benefits when making a proportionality determination.

Yet, there is logical leap in understanding this and other similar statements as support for the proposition that the damage to the civilian use of a military objective constitutes incidental harm for the purposes of a proportionality assessment. Attacks against ‘dual-use’ infrastructure can often have reverberating effects that are reasonably expected to physically harm civilians or civilian objects. For example, an attack on a bridge, which according to reliable intelligence sources will be used by the adversary in its advance, can also have the effect of preventing first responders from accessing points made reachable through the bridge. Death and injury, as well as damage to other (civilian) objects, can thus, depending on the circumstances, be expected to result from attacks such ‘dual-use’ infrastructure, and therefore must be included in a proportionality assessment. This latter understanding appears to be uncontroversial, and does not undermine the conclusion that damage to civilian use of a structure which, as a whole, serves both civilian and military functions need not be included in a proportionality assessment.

Is a different conclusion warranted regarding when different parts of a single structure are being used for civilian and military functions? Similar to the conclusion reached regarding the spatial scope of objects under API, it would appear that in their practice too, states tend treat structures as whole single objects, rather than being conglomerations thereof (eg, Australia; Canada; Denmark (with certain caveats, of less relevance here); Netherlands; Romania; Syria; United States; Viet Nam; see also UNSC Res 2573 (2021), preamble ¶10). Hence, the use of part of a structure for military function would render it as a whole a military objective, which need not be considered in a proportionality assessment.

IV. Concluding Observations                  

For the reasons set out above, it is submitted that, under both treaty and customary IHL, a military commander is not obligated to consider the civilian use of a military objective in the context of a proportionality assessment. In this regard, to quote Emanuela-Chiara Gillard’s Chatham House proportionality report, ‘there does not appear to be any legal basis for taking into account damage to the dual-use object in proportionality assessments’.

Nevertheless, the questions addressed in this post are only some of an array of legal questions relevant to assessing the legality of an attack. In addition to questions relating to distinction and precautions, and as alluded to above, an attack on a military objective which also serves civilian functions may have reverberating effects, which must be included in a proportionality assessment. Thus, regardless of whether one accepts the arguments of this piece, there are other questions which must be answered before concluding that an attack is lawful.