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Max Planck Encyclopedia of Public International Law [MPEPIL]

Precautions in Attack

Wolff Heintschel von Heinegg

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2015. All Rights Reserved. Subscriber: null; date: 27 February 2020

Geneva Conventions 1949 Additional Protocol 1 — Military objectives — Proportionality

Published under the auspices of the Max Planck Foundation for International Peace and the Rule of Law under the direction of Rüdiger Wolfrum.

A.  Introduction

The object and purpose of the duty to take precautions in attack is to improve the protection of the civilian population, civilians and civilian objects against the effects of hostilities and it, thus, is a necessary corollary of the principle of distinction (Civilian Population in Armed Conflict). Other than the prohibition of excessive collateral damage (Proportionality and Collateral Damage), it is procedural in nature and in most parts dependent upon objective rather than subjective criteria. The obligation is relative insofar as the concept of feasibility applies. It needs to be emphasized that the prohibition of direct attacks against the civilian population, civilians, and civilian objects is absolute in nature and that the precautionary obligations may not be construed as authorizing such attacks, Art. 57 (5) Geneva Conventions Additional Protocol I (1977) (‘AP I’). The general obligation on precautions is supplemented by specific obligations regarding certain weapons (eg mines, incendiary weapons, laser systems, explosive ordnance) and attacks against works and installations containing dangerous forces (Art. 56 AP I). The obligation to take precautions in attack (‘active precautions’) is to be distinguished from so-called ‘passive precautions’, ie those that, according to Art. 58 AP I, must be taken against the effects of attacks.

B.  Legal Basis and Scope of Applicability

With regard to international armed conflicts, the obligation to take precautions has been codified in Art. 57 AP I, which widely reflects customary international humanitarian law (DoD Manual paras 5.3.3, 5.11; ICRC Study Rule 22). Accordingly, it equally applies to air warfare (AMW Manual Rules 30–41), naval warfare (SRM para. 46; NWP 1–14M para. 8.1) and cyber warfare (Tallinn Manual Rules 52–58).

Despite the comparatively rudimentary wording of Art. 13 (1) Additional Protocol II (‘AP II’) it is generally agreed that the obligation to take precautions in attack also applies in non-international armed conflicts (ICRC Study 69 et seq; NIAC Manual para. 2.1.2; AMW Manual Commentary 124).

C.  Impact on the Targeting Process

Without prejudice to the obligation to take constant care, the obligation to take precautions in attack has a considerable impact on the planning, ordering, and execution of attacks against lawful targets. Accordingly, in the course of the targeting process, the following steps must be taken:

  1. 1.  Verification of legality of the target, Art. 57 (2) (a) (i) AP I.

  2. 2.  Legality of the method or means to be employed (yardstick: ‘weapons law’).

  3. 3.  Determination of probability of collateral damage.

  4. 4.  If collateral damage is expected to be excessive, the attack is unlawful according to Art. 51 (5) (b) AP I, and it may not be ordered or executed, Art. 57 (2) (a) (iii) AP I.

  5. 5.  If collateral damage is not expected to be excessive, there is an obligation to minimize or avoid collateral damage by all feasible precautions, Art. 57 (2) (a) (ii) AP I, eg by choice of a different weapon (‘weaponeering’) or of another time of attack. In case of choice between several military objectives, the objective must be selected, the attack on which may be expected to cause the least danger to civilian lives and to civilian objects, Art. 57 (3) AP I.

  6. 6.  If collateral damage is not expected to be excessive, an effective advance warning must be given, unless circumstances do not permit, Art. 57 (2) (c) AP I.

  7. 7.  If circumstances change after approval of the attack, it must be cancelled or suspended, Art. 57 (2) (b) AP I.

  8. 8.  If attack is approved, the duty to take constant care continues to apply, Art. 57 (1) AP I.

D.  Precautionary Obligations

It is important to note that the obligation to take precautions is not limited to attacks, that is, to acts of violence as defined in Art. 49 (1) AP I (ie those acts expected to cause injury or death to persons or damage or destruction to objects). Whereas the obligations according to Art. 57 (2) and (3) AP I apply to attacks only, those according to Art. 57 (1) and (4) AP I apply to military operations. The term ‘military operations’ ‘has a wider connotation than “attacks”’ (UK Manual para. 5.32) and would include ‘any movements, manoeuvres and other activities whatsoever carried out by the armed forces with a view to combat’ (ICRC Commentary MN 2191). Whereas every ‘attack’ is a ‘military operation’, not every ‘military operation’ qualifies as ‘attack’.

1.  Constant Care

Although the obligation to take constant care has been characterized as a ‘general principle’ (ICRC Commentary MN 2191), and although the title of Art. 57 AP I seems to limit precautions to ‘attacks’, it must be considered a stand-alone obligation that is independent from the precautionary obligations applying to attacks. The requirement of ‘constant care’ means that the parties to an armed conflict may not disregard the general protection the civilian population and individual civilians enjoy against dangers arising from military operations (Art. 51 (1) AP I), although they are engaged in active hostilities. The duty ‘requires commanders and all others involved in the operations to be continuously sensitive to the effects of their activities on the civilian population and civilian objects, and to seek to avoid any unnecessary effects thereon. … The word “constant” denotes that the duty … is of a continuing nature throughout all … operations; all those involved in the operation must discharge the duty. The law admits of no situation in which, or time when, individuals involved in the planning and execution process may ignore the effects of their operations on civilians or civilian objects’ (Tallinn Manual 166). ‘In planning or deciding on or carrying out attacks, however, those responsible have more specific duties’ (UK Manual para. 5.32.1).

2.  Obligations with Respect to Attacks

(a)  Concept of Feasibility

The precautions that must be taken by those who plan or decide upon an attack with a view to verifying the legality of the target (Art. 57 (2) (a) (i) AP I) and to minimizing non-excessive collateral (Art. 57 (2) (a) (ii) AP I) are not absolute in nature but limited to ‘feasibility’. The term ‘feasible’ has been defined in Art. 3 (4) AP II and in Art. 3 (10) Amended Protocol II to the 1980 Conventional Weapons Convention: ‘Feasible precautions are those precautions which are practicable or practically possible taking into account all circumstances ruling at the time, including humanitarian and military considerations.’ The same text has been used by the United Kingdom and other States in their declarations made upon ratification of AP I, and it seems to correctly reflect the lex lata (ICRC Study 54; AMW Manual Rule 1 (q); Tallinn Manual 168).

‘Feasibility is an inherently variable and circumstantial concept. Accordingly, the feasibility of verifying the nature of a target is dependent upon ‘the information actually available at the time of the decision’ (declaration made by Austria upon ratification of AP I), which means that ‘military commanders and others responsible for planning, deciding upon or executing attacks, necessarily have to reach their decisions on the basis of their assessment of the information from all sources, which is available to them at the relevant time’ (declaration made by Australia upon ratification of AP I). ‘This is a clear rejection of any hindsight analysis’ (AMW Manual Commentary 38).

Feasibility is to be determined by taking into account humanitarian and military considerations. Those planning, ordering, or executing an attack may, therefore, take into consideration the success of the ‘attack as a whole’ and the protection of own forces, such as the survival of military personnel and equipment. This, however, does not mean that minimizing own risks will always prevail over considerations of humanity. Given that both considerations are of equal relevance, ‘the factoring in of such military considerations may not result in a neglect of humanitarian obligations’ (AMW Manual Commentary 39). ‘What is called for is a reasonable ‘allocation of risk’ between the attacker’s military personnel and the enemy civilians’ (Dinstein 141).

10  The concept of feasibility introduces a double standard into the law applicable to the conduct of hostilities insofar as the determination of what is practicable or practically possible is dependent upon what is reasonably available to those responsible for the attack. In the circumstances ruling at the time, a party to the conflict that possesses technologically advanced equipment may therefore have to meet standards that are higher than those incumbent on a party to the conflict having less advanced means. This, however, does not mean that technologically advanced armed forces are obliged to always employ technologically advanced means of warfare, such as precision guided munition (‘PGM’) (Dinstein 142).

(b)  Verification of Lawful Targets

11  The obligation according to Art. 57 (2) (a) (i) AP I requires all those responsible for the attack to use all means at their disposal to verify that a target is a lawful military objective and that it does not benefit from general or specific protection under international humanitarian law. Means designed to verify the true nature of a target include, but are not limited to, intelligence, surveillance, and reconnaissance (ISR systems). They may also include so-called ‘human sources’ provided the individual giving the information has proven to be sufficiently reliable.

12  According to the UK Manual (para. 5.32.2), the ‘commander selecting a target will have to pay regard to some or all of the following factors before he makes up his mind to attack it:

  1. a.  whether he can personally verify the target;

  2. b.  instructions from higher authority about objects which are not to be targeted;

  3. c.  intelligence reports, aerial or satellite reconnaissance pictures, and any other information in his possession about the nature of the proposed target;

  4. d.  any rule of engagement imposed by higher authority under which he is required to operate;

  5. e.  the risks to his own forces necessitated by target verification.’

13  In view of the applicability of the concept of feasibility, the information need not be ‘beyond reasonable doubt’. It suffices if any reasonable commander, in the circumstances ruling at the time, would have arrived at the conclusion that the target is a lawful military objective. Hence, there would be no violation of the obligation to take feasible precautions even if a post-event analysis revealed that the target was not a lawful military objective (Dinstein 139). However, the information must be ‘up to date, ie collated and interpreted just prior to the time of action’ (Dinstein 140). Moreover, in view of the obligation of constant care, the parties to the conflict ‘ought to retain a command and control system capable of collecting, processing relevant information, making the necessary evaluation and directing its combat units accordingly’ (AMW Manual Commentary 126; see also UK Manual para. 5.32.3).

(c)  Avoiding and Minimizing ‘Collateral Damage’

14  The obligation to minimize ‘collateral damage’ comes into operation in two situations.

15  According to Art. 57 (2) (a) (ii) AP I, those responsible for the attack must choose the means or method of warfare that avoids, and in any event minimizes, ‘collateral damage’. This obligation only applies if there is a probability of collateral damage and if the collateral damage is not expected to be ‘excessive’. It requires those responsible for the attack to consider alternative weapons, another time of attack or another angle. Accordingly, ‘an attacker ought to choose a weapon with greater precision or lesser explosive force if doing so would minimize the likelihood of collateral damage, assuming the selection is militarily feasible’ (AMW Manual Commentary 127). As to the factors a commander should have regard to when choosing the means or methods of attack, see UK Manual para. 5.32.5.

16  The obligation according to Art. 57 (3) AP I applies when ‘two or more potential targets for attack actually offer a similar military advantage while expected to produce dissimilar collateral damage to civilians or civilian objects’ (Dinstein 140). The phrase ‘similar military advantage’ must be ‘understood in terms of the military advantage anticipated from the attack considered as a whole and not only from isolated or particular parts of the attack’ (AMW Manual Commentary 128). The requirement to select among several objectives does not apply ‘if doing so would be militarily unreasonable’ (AMW Manual Commentary 129).

(d)  Refraining from Attacks

17  The obligation under Art. 57 (2) (a) (iii) AP I to refrain from an attack, which may be expected to cause excessive ‘collateral damage’ is a necessary consequence of the prohibition of such attacks according to Art. 51 (5) (b) AP I. In view of its declaratory nature it is not a precautionary obligation strictu sensu.

(e)  Cancellation or Suspension of Attacks

18  The obligation under Art. 57 (2) (b) AP I applies, if ‘it becomes apparent’ that the respective attack would be unlawful because the objective chosen is not military or (specially) protected, or if the collateral damage is expected to be excessive. The obligation, therefore, comes into operation after those responsible for the attack have taken the required feasible precautions under Art. 57 (2) (a) (i) and (ii) AP I, have decided to attack the target, and if the factual basis of their decision changes because new facts have emerged. This follows from the wording, which suggests that the attack has already been approved, because otherwise it could not be cancelled or suspended. Moreover, ‘apparent’ means ‘readily perceived or understood, obvious’. If, due to changed circumstances, it becomes so apparent that the attack would be unlawful, the obligation to cancel or suspend is strict and absolute in character. Suspension or cancellation is not subject to feasibility, which includes considerations of military necessity, but it is objective insofar as the responsible commander is in the position to take a decision to that effect.

19  The obligation to cancel or suspend is not limited to military planners and military commanders, but it is incumbent on all members of the armed forces who have the practical possibility to cancel or suspend the attack, which includes ‘single soldiers opening fire on their own initiative’ (UK Manual para. 5.32.9).

(f)  Advance Effective Warnings

20  The obligation to give advance warnings has been introduced into international humanitarian treaty law by Art. 26 1907 Hague Regulations and by Art. 6 1907 Hague Convention (IX). Hence, it may be held that Art. 57 (2) (c) AP I is reflective of customary international humanitarian law (AMW Manual Rule 37; Tallinn Manual Rule 58).

21  The general duty to issue advance warnings must be distinguished from special warnings that must be given prior to attacks against persons and objects entitled to specific protection, such as medical units (Art. 21 Geneva Convention I [‘GC I’]), hospital ships (Art. 34 (1) Geneva Convention II [‘GC II’]), civilian hospitals (Art. 19 Geneva Convention IV [‘GC IV’], civilian medical units (Art. 13 AP I) and civil defence (Art. 65 (1) AP I) (Geneva Conventions I–IV [1949]).

22  The duty to give advance warnings only applies if the attack ‘may affect the civilian population’. Accordingly, it does not apply if ‘military operations are being conducted in an area where there is no civilian population or if the attack is not going to affect the civilian population at all’ (UK Manual para. 5.32.8). It neither applies, if attacks ‘may result only in damage to, or destruction of, civilian objects’ (AMW Manual Commentary 133). Although the term ‘affect’ is comparatively broad, it does not include ‘mere inconveniences to civilians caused by, eg, electrical blackouts or reduced mobility due to broken lines of communications’ (ibid).

23  In other situations, the duty to issue advance warnings is subject to whether circumstances permit. In particular, a warning need not be given if that ‘would deprive the attacker of the element of surprise’ or if it would ‘allow the defender to enhance target area defences’ (AMW Manual Commentary 133).

24  The warning must be ‘effective’. This requires that it can reach the civilian population likely to be affected and to be comprehensible, ie in a language understood by the civilian population. Moreover, the warning ‘ought not be vague but be as specific as circumstances permit to allow the civilian population to take relevant protective measures, like seeking shelter or staying away from particular locations’ (AMW Manual Commentary 133).

25  As regards the form of warning, the parties enjoy a wide margin of discretion as long as the warning is effective. Accordingly, warnings may be given by dropping leaflets, radio or TV broadcasts, or text messages.

3.  Military Operations at Sea or in the Air

26  The scope of applicability of Art. 57 (4) AP I must be determined in the light of Art. 49 (3) AP I. Accordingly, the obligations under Art. 57 (1) to (3) AP I, apply to ‘all attacks from the sea or from the air against objects on land’, and there is no room for Art. 57 (4) AP I. This provision is, therefore, ‘more concerned with the effects on the civilian population and civilian objects of military operations at sea or in the air’ (ICRC Commentary MN 2230).

27  Air or naval operations that may have an effect on the civilian population or civilian objects on land without being directed against targets on land (eg sea-to-sea, air-to-air, air-to-sea or sea-to-air operations) are not subjected to the standard of feasibility but to ‘all reasonable precautions’. According to the ICRC, this is ‘undoubtedly slightly different from and a little less far-reaching than the expression ‘take all feasible precautions’, used in paragraph 2. As the nuance is tenuous, the purpose of the provision appears to be to reaffirm the rules that exist to protect civilians in such situations’ (ICRC Commentary MN 2230). In view of the wording, it may be doubted whether the nuance is indeed tenuous. Moreover, it has to be observed that during military operations at sea or in the air that are not directed against targets on land, those responsible for the attacks or operations will hardly have a choice between different kinds of weapons or to suspend the attack against targets in the air or at sea. Therefore, the lesser standard of reasonableness makes perfectly sense.

28  It needs to be emphasized, however, that military operations in the air or at sea, whose effects may not extend to land, continue to be governed by the customary obligation to take precautions in attack, which include the feasibility standard (AMW Manual Rules 30–39; SRM para. 46).

E.  Final Observations

29  The duty to take precautions in attack has been misunderstood as obliging the parties to an armed conflict to always employ highly advanced and precise weapons, or to refrain from attacks against lawful targets if it is impossible to avoid ‘collateral damage’. As seen, this is not what international law requires. If the parties to an armed conflict, for operational or political reasons, choose to apply stricter standards, such as individual text messages to those who may be affected by an attack, this is not indicative of an opinio iuris.