The second part of this two-part blog on partnering in warfare discusses the issues of ensuring respect for IHL and State responsibility for internationally wrongful acts, including violations of international humanitarian law (IHL). See Part 1 on the introduction and setting the legal framework.


Fighting together and international humanitarian law: Ensuring respect for IHL

States may support the Parties to an armed conflict through a wide range of possible activities, including training, equipping or partnered operations. Such States are in a unique position to influence the behaviour of their partners. With this capacity to influence comes a greater responsibility—and opportunity—to ensure respect for IHL.

The obligation to respect and ensure respect for IHL is set down in Common Article 1 of the four Geneva Conventions of 1949, the first and third Additional Protocols, as well as in customary IHL[1]. This obligation applies at all times and irrespective of whether or not the State itself is a Party to the armed conflict. The ICRC’s Commentary to the First Geneva Convention, Article 1, which is the subject of ongoing discussion, distinguishes two aspects of the obligation to ensure respect:

  • A negative obligation[2] to refrain from encouraging or assisting violations of IHL; and
  • A positive obligation[3] to take feasible measures in order to influence the Parties to the conflict and bring them to an attitude of respect for IHL.

The negative obligation

The negative obligation to ensure respect is an obligation of result. No support may be provided that would encourage, aid or assist violations of IHL. Regardless of its subjective intention (contrast aiding or assisting for the purposes of the law of State responsibility, below), a State must not ‘knowingly contribute to violations of the Conventions by a Party to a conflict[4].’ That is, States must not provide support to a Party to an armed conflict where there is an ‘expectation, based on facts or knowledge of past patterns, that[5]’ such support would be used to violate IHL.

The positive obligation

By contrast, the nature and extent of the actions required by the positive obligation to ‘ensure respect’ will depend on all the circumstances. It is an obligation of due diligence: the greater the support provided to a Party to an armed conflict, the more extensive the measures required on the part of the supporting State will be.

States may exercise their influence in many ways to stop violations of IHL, including by withdrawing support—which, ideally, had been conditioned from the outset upon steadfast adherence to the law. In fact, using the means at its disposal, a State might withdraw or suspend support that has no direct causal link to the violations as such.

Beyond stopping violations, the ICRC’s Commentary to the First Geneva Convention states that the positive obligation of Common Article 1 also requires that measures be taken to prevent them[6]. There are an infinite array of possible actions, many of them very pragmatic, that States can take to prevent violations of IHL. Often, the difficult question is whether a State would exercise greater influence to prevent violations by more presence and increased engagement or, conversely, by distancing itself from its ally or partner’s actions. In the authors’ view, this assessment is best made on a case-by-case basis.

Arms transfers

Finally, States that transfer weapons and other military items to armed groups can be considered particularly influential owing to their ability to provide or withhold the means by which violations can be committed. Beyond the obligation to ensure respect for IHL, with the entry into force of the Arms Trade Treaty in 2014, and in light of regional export control instruments such as the EU Common Position or the ECOWAS Convention on Small Arms and Light Weapons, States are generally prohibited from authorizing exports[7] of arms or ammunition if there is a clear or substantial risk that they could be used to commit or facilitate serious violations of IHL or international human rights law.

Fighting together and international humanitarian law: Assessing responsibility for violations

First and foremost, the Parties to armed conflict are responsible for their own behaviour. States are directly responsible for acts committed by their own organs[8]. In the context of partnerships, including activities that are undertaken in the framework of a coalition, the responsibility of States may also be engaged in several other ways. Where the conditions for attribution are met, a State may be responsible for a violation of any of the obligations that are incumbent upon it, including those of IHL.

A State will incur responsibility where it aids or assists[9] another State in the commission of an internationally wrongful act to the extent that its own conduct has caused or contributed to that act. For the responsibility of a State in connection with the act of another State in this way, there are controversies as to the existence of a requirement of intent[10] (contrast the obligation to ensure respect for IHL, noted above) to facilitate the wrongful conduct and in respect of the ‘relationship between knowledge and intent’. It is not possible to make a definitive list of what support or conduct could constitute ‘aiding and assisting’—rather, the circumstances of each case must be carefully taken into account to assess the contribution of that support to the commission of the wrongful act. Examples could include financing; the provision of an essential facility[11]; furnishing weapons or other military assistance or logistics support, or; the provision of territory or intelligence.

Responsibility may also arise as a result of coercion[12], or in the case of direction and control[13] of the commission of an act by another State. In practice, even where—as occurs today—one State ‘leads’ a coalition of State partners, direction and control would only engender State responsibility in case of the fulfilment of the high threshold criteria of domination of the commission of the wrongful conduct[14].

States might also be responsible for ‘aiding or assisting’ the unlawful conduct of an armed group and can incur liability in several other ways, including for the conduct of private persons or groups acting under their instruction, direction or control[15]. There are divergent views in international jurisprudence as to the level of control required to trigger State responsibility for the conduct of organised groups. For its part, the International Criminal Tribunal for the former Yugoslavia, recalling the ‘logic of the law of state responsibility’, found that organised groups under the ‘overall control of a State… must perforce engage the responsibility of that State for [all of their] activities,’ and, referencing ‘judicial and State practice’, concluded that overall control determines attribution of an organized ‘group to a State’.

In support of this position, the ICRC’s Commentary to the First Geneva Convention notes that the overall control test is most ‘appropriate because [it] better reflects the real relationship between… armed group[s] and the [controlling] State, including for the purpose of attribution’. The result is that the armed group becomes subordinated to the State and the members of the group become its ‘agents’ for whom it is responsible under international law. In IHL terms, the obligations of the State would thus extend beyond ‘ensuring [others’] respect’—to ‘respecting’ its own IHL obligations in regard to actions related to the conflict. The ICRC’s Commentary[16] also recognises, however, that the position that overall control results in attribution—distinct from classification—is not uniformly accepted[17].

State responsibility might also arise where a State exercises short-term ‘effective control[18]’—i.e. direction or enforcement[19]—of the commission of a breach of its international obligations by the group’s members. Although overall control is sometimes described as a ‘lower-threshold’ standard than effective control, the absence of the former does not necessarily preclude attribution on the basis of the latter. This contention is explained by the fact that the two tests are relevant considerations for different ‘controls’—overall control for ‘military’ groups and effective control for individuals / unorganized groups—and fundamentally describe different relationships: prolonged or punctual control, respectively.

Finally, in addition to situations of ‘control’, State responsibility may arise for the conduct of a group that is ‘empowered by the law of that State to exercise elements of the governmental authority[20]’ (such as local law enforcement), or for the conduct of a group that the State subsequently acknowledges and adopts as its own[21].


This two-part blog notes that, through the provision of support to one or more Parties to armed conflict, a State may itself become bound by IHL. States are required to ensure respect for IHL and may, moreover, be liable for violations—including of IHL—committed by their partners or allies.

Ultimately, States that provide support to Parties to armed conflict must do so within the relevant frameworks set by international law. Steadfast adherence to and vocal support for international law, including IHL as applicable, is the first means by which States can influence the behavior of their partners and allies: a constructive, lawful example to others benefits the victims of armed conflict.


Cordula Droege is the Chief of Staff for the President, International Committee of the Red Cross. She was previously the Head of Unit of the ICRC Legal Advisers to the Operations.

David Tuck is Legal Adviser to the Operations at the ICRC.

This article has been written in the personal capacity of the authors.


For other posts in the Fighting together series, see



[1] See also for interest, Dörmann, K., and Serralvo, J., Common Article 1 to the Geneva Conventions and the obligation to prevent international humanitarian law violations,

[2] GC I Commentary, Article, paras 158–163.

[3] GC I Commentary, Article, paras 164–173.

[4] GC I Commentary, Article, para 159.

[5] GC I Commentary, Article, para 161.

[6] GCI Commentary Article 1, para 164.

[7] Arms Trade Treaty, Article 7. See also ICRC, IHL Challenges Report 2015, pp. 55–56,

[8] ARSIWA, Article 4. See also Customary Law Study, Rule 149,

[9] ARSIWA, Article 16.

[10] Aust, H.P., Complicity and the Law of State Responsibility, pp. 230–249.

[11] ARISWA, Commentary to Article 16, para 1.

[12] ARISWA, Article 18.

[13] ARISWA, Article 17.

[14] ARISWA, Commentary to Article 17, para 7.

[15] ARISWA, Article 8.

[16] GCI Commentary, Article 3, para 408.

[17] ICJ, Application of the Convention on the prevention and punishment of the crime of genocide (Bosnia and Herzegovina v. Serbia and Montenegro), 26 February 2007, paras 398–407.

[18] ICJ Genocide case, paras 397–400.

[19] ICJ, Nicaragua v. United States of America, 27 June 1986, para 115.

[20] ARISWA, Article 5. See also Customary Law Study, Rule 149,

[21] ARISWA, Article 11 and Commentary to Article 11. See also Customary Law Study, Rule 149.