¹ See Nolte, G and Aust, H, ‘Equivocal Helpers: Complicit States, Mixed Messages and International Law’ (2009) 58(1) ICLQ 1–30 Google Scholar.

² UK Cabinet Office, The Report of the Detainee Inquiry (2013) 4–5 <https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/267695/The_Report_of_the_Detainee_Inquiry_December_2013.pdf>.

³ See, for example, J Serle, ‘UK Complicity in US Drone Strikes Is ‘Inevitable’, Emmerson tells Parliament’ (Bureau of Investigative Journalism, 5 December 2013) <https://www.thebureauinvestigates.com/2013/12/05/uk-complicity-in-us-drone-strikes-is-inevitable-emmerson-tells-parliament/>.

⁴ Campaign Against the Arms Trade v Secretary of State for Business, Innovation and Skills & Others, CO/1306/2016. The claimants alleged that the sale contravened the Consolidated EU and National Arms Export Licensing Criteria. An intervention by Amnesty International, Human Rights Watch and Rights Watch (UK) also alleged that the sale contravened art 16 of the International Law Commission's Articles on State Responsibility. In a judgment of 10 July 2017, the High Court dismissed the Claimant's claim for judicial review. The claimants have sought leave to appeal.

⁵ Jackson, M, Complicity in International Law (Oxford University Press 2015) 172 Google Scholar.

⁶ See, for example, Aust, H, Complicity and the Law of State Responsibility (Cambridge University Press 2011)CrossRefGoogle Scholar; Jackson (n 5); and Lanovoy, V, Complicity and Its Limits in the Law of Responsibility (Hart 2016)Google Scholar.

⁷ For discussion of these other rules and their relationship to art 16, see Moynihan, ‘Aiding and Assisting: Challenges in Armed Conflict and Counterterrorism’, (2016) Chatham House Research Paper, ch 3.

⁸ See International Law Commission, ‘State Responsibility – Comments and Observations Received from Governments’ (2001) 53rd session, 52 (UN Doc A/CN.4/515) for the comments of the UK.

⁹ See V Lanovoy, ‘Complicity in an Internationally Wrongful Act’ (2014) SHARES Research Paper 38, 4. Lanovoy notes that Special Rapporteur Roberto Ago used the term ‘complicity’ but dropped it after criticisms from States and some ILC members.

¹⁰ ILC Commentary to Article 16 of the Articles on State Responsibility, para (3).

¹¹ The UN General Assembly's Sixth Committee has established a Working Group on the Responsibility of States for Internationally Wrongful Acts to consider further the question of whether the Articles on State Responsibility should be turned into a Convention (UNGA Res 68/104 of 16 December 2013 on the Responsibility of States for Internationally Wrongful Acts).

¹² Crawford, J, State Responsibility: The General Part (Cambridge University Press 2013) 408 Google Scholar.

¹³ Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Serbia and Montenegro) (Judgment) (2007) ICJ Rep 43, para 417 (Bosnian Genocide case). For detailed analysis of the customary law status of art 16, see Aust (n 6) 97–191.

¹⁴ See ILC Commentary to art 16, paras (1) and (10); and Lowe, V, ‘Responsibility for the Conduct of Other States’ (2002) 101 Kokusaiho Gaiko Zassi 11 Google Scholar.

¹⁵ For a fuller analysis of each of the conditions under art 16, see Moynihan (n 7).

¹⁶ The ILC Commentary to art 16 states that ‘the aid or assistance must be given with a view to facilitating the commission of that act, and must actually do so’ (emphasis added), para (3).

¹⁷ See, for example, N Melzer, ‘Human Rights Implications of the Usage of Drones and Unmanned Robots in Warfare’ European Parliament Directorate-General for External Policies of the Union (2013) 38.

¹⁸ ILC Commentary to art 16, para (4).

¹⁹ See Crawford (n 12) 407, citing Dominicé, C ‘Attribution of conduct to multiple States and the implication of a State in the act of another State’, in Crawford, J, Pellet, A and Olleson, S (eds), The Law of International Responsibility (Oxford University Press 2010) 286 Google Scholar, who refers to the need for ‘specific knowledge of … an internationally wrongful act with a high degree of particularity’ (emphasis added) when referring to the ICJ's decision in the Bosnian Genocide case. See also Nolte and Aust (n 1) 12.

²⁰ Lowe (n 15) 9–10.

²¹ Statement at the 2577th Meeting of the ILC, Yearbook of the International Law Commission (1999) Vol I, 69, para 13.

²² Bosnian Genocide case (n 13): ‘… there is no doubt that the conduct of an organ or a person furnishing aid or assistance to a perpetrator of the crime of genocide cannot be treated as complicity in genocide unless at the least that organ or person acted knowingly, that is to say, in particular, was aware of the specific intent (dolus specialis) of the principal perpetrator’, para 421 (emphasis added).

²³ Crawford also takes this reference in the Bosnian Genocide case to ‘at the least’, as quoted in note 22 above, to indicate that something more than mere knowledge is required, ‘namely the need for actual intent that aid and assistance be given to the illegal act’. See Crawford (n 12) 407. See also Dominicé (n 19) 286; Nolte and Aust (n 1) 14; Aust (n 6) 236; cf Jackson (n 5) 160.

²⁴ Statement of Special Rapporteur James Crawford at the 2577th Meeting of the ILC, Yearbook of the International Law Commission (1999) Vol I, 69, para 14.

²⁵ For example, States, such as the US, which are not party to Additional Protocol II to the Geneva Conventions and which consider that they are bound by some provisions as a matter of custom but not by others.

²⁶ As is reflected in Serdar Mohammed v Ministry of Defence [2017] UKSC 1 and [2017] UKSC 2.

²⁷ Nolte and Aust (n 1) 12.

²⁸ Crawford (n 12) 406; Jackson (n 5) 161; Lowe (n 14) 10.

²⁹ Crawford (n 12) 408 refers to ‘actual or near-certain knowledge’ in relation to imputation with intent (emphasis added). Jackson (n 5) 161 argues that ‘knowing participation means awareness with something approaching practical certainty as to the circumstances of the principal wrongful act’.

³⁰ International Law Commission, Yearbook of the International Law Commission (1978) Vol 2, Pt II, 111, para 10 (UN Doc A/CN.4/SER.A/1978/Add.1 (Pt 2)). For discussion of this, see Quigley, J, ‘Complicity in International Law: A New Direction in the Law of State Responsibility’ (1986) 57(1) BYBIL 113 Google Scholar.

³¹ Quigley (n 30) 113.

³² Statement of the Netherlands in the International Law Commission, Yearbook of the International Law Commission (2001) Vol II(1), 52 (emphasis added). See also the statements of Ustor in the International Law Commission, Yearbook of the International Law Commission (1975) Vol I, 48, cited in Crawford (n 12) 406.

³³ Lowe (n 14) 10.

³⁴ ibid.

³⁵ ibid 11.

³⁶ For a discussion of the views of different States during the ILC negotiations on the mental element, see Aust (n 6) 172 and 233–35.

³⁷ Bosnian Genocide case (n 13) [421]; see also discussion in Jackson (n 5) 160.

³⁸ For example, Jackson (n 5) 54 and 162.

³⁹ Williams, G ‘Criminal Law: The General Part’ (Stevens & Sons, London 1961) 159 Google Scholar, quoted by Jackson (n 6) 54.

⁴⁰ W Dellinger, Assistant Attorney General, Office of Legal Counsel, ‘Memorandum Opinion for the Deputy Attorney General on US Assistance to Countries That Shoot Down Civil Aircraft Involved in Drug Trafficking’ (14 July 1994) 157, quoting the case of Giovannetti, 919 F.2d at 1229.

⁴¹ ibid.

⁴² Lowe (n 14) 10 states that ‘… it is in my view unlikely that a tribunal would permit a State to avoid responsibility by deliberately holding back from inquiring into clear indications that its aid would probably be employed in an unlawful manner’; Jackson (n 5) 162; Quigley (n 30) 120 also suggests that where a State has information about the recipient State's plans for illegality, it should not be allowed to turn a blind eye.

⁴³ See Jackson (n 5) 162, arguing that ‘Beyond that [wilful blindness], international law does not yet recognize a general due diligence obligation conditioning the provision of aid or assistance to another State’, and suggesting that wilful blindness implies some form of due diligence obligation.

⁴⁴ This concept, which is gaining increasing traction in international law, has been defined as ‘reasonable efforts by a State to inform itself of factual or legal components that relate foreseeably to a contemplated procedure and to take appropriate measures in timely fashion to address them’. See International Law Association, First Report of the ILA Study Group on Due Diligence in International Law (2014) 6–7, quoting Stephens, T, International Courts and Environmental Protection (Cambridge University Press 2009) 158 CrossRefGoogle Scholar.

⁴⁵ Prosecutor v Blaskic, ICTY Appeals Chamber, IT-95-14-A, Judgment of 29 July 2004 [406].

⁴⁶ The Commentary to art 2 provides that the articles lay down no general rule in relation to standards, whether they involve ‘some degree of fault, negligence or want of due diligence’ on the part of the State to which a wrongful act is attributed under art 2, instead leaving this to the content of the primary obligation in question (para (3), 82).

⁴⁷ A Boivin, ‘Complicity and Beyond: International Law and the Transfer of Small Arms and Light Weapons’ (2015) 87(859) International Review of the Red Cross 471; ILC Commentary to art 2, para (3), 82 and para (10), 84.

⁴⁸ For an example of the application of the due diligence principle under international human rights law in relation to cases on assistance, see El Masri v Macedonia (App No 39630/09, 13 December 2012). The European Court of Human Rights held that Macedonia, in its assistance to the US in the ill-treatment of the applicant, had failed to take reasonable steps to avoid a risk of ill-treatment about which it knew or ought to have known. While the court referred to art 16 as a relevant norm of international law in its reasoning (para 97), it ultimately considered the issue of responsibility under the relevant provisions of the ECHR. For further discussion see Moynihan (n 7) paras 102ff.

⁴⁹ Quigley (n 30) 111.

⁵⁰ Corfu Channel case (UK v Albania) (Merits) [1949] ICJ Rep 4.

⁵¹ Aust (n 6) 245. The facts of the case have led some to argue that this was in fact a case of joint (and thus direct) responsibility under art 47 of the Articles on State Responsibility rather than ancillary responsibility for aid or assistance under art 16; Crawford (n 12) 658. In practice, the distinction is often difficult to draw.

⁵² Bethlehem, D, ‘The Secret Life of International Law’ (2012) 1 CJICL 34 CrossRefGoogle Scholar; Boivin (n 47) 471.

⁵³ Lanovoy (n 9) 21.

⁵⁴ See arguments referred to in Aust (n 6) 236.

⁵⁵ Gaya, G, ‘Interpreting Articles Adopted by the International Law Commission’ (2015) 86 BYBIL 1 Google Scholar.

⁵⁶ Quigley (n 30) 11.

⁵⁷ Gibney, M, Tomasevski, K and Vedsted-Hansen, J, ‘Transnational State Responsibility for Violations of Human Rights’ (1999) 12 HarvHumRtsJ 294 Google Scholar; Quigley (n 30) 111.

⁵⁸ Crawford (n 12) 87.

⁵⁹ See ILC Commentary to art 14 of the Draft Articles on the Responsibility of International Organizations, para (4) 37.

⁶⁰ Aust, H, ‘The UN Human Rights Due Diligence Policy: An Effective Mechanism against Complicity of Peacekeeping Forces?’ (2015) 20(1) JC&SL 69 Google Scholar. For discussion of the views of different States on the intent requirement, see Aust (n 6) 172.

⁶¹ Comments of the US Government in the 50th session of the ILC (22 October 1997) UN Doc A/CN.4/488.

⁶² See Chinkin quoted in Aust (n 6) 240; and generally Aust at 239ff and 427 on these legal policy arguments. Crawford (n 12) 408; Aust (n 60) 69 and fn 35 quoting Crawford.

⁶³ Gibney, Tomasevski and Vedsted-Hansen (n 57) 12; Nahapetian, K ‘Confronting State Complicity in International Law’ (2002) 52 ICLQ 108 Google Scholar; Quigley (n 30) 111; Howard, J, ‘Invoking State Responsibility for Aiding the Commission of International Crimes – Australia, the US and the Question of East Timor’ (2001) 2 Melbourne Journal of International Law 46 Google Scholar.

⁶⁴ Quigley (n 30) 117.

⁶⁵ Crawford (n 12) 408; Nolte and Aust (n 1) 15–16.

⁶⁶ See, for example, Van Sliedregt, E, Individual Criminal Responsibility in International Law (Oxford University Press 2012) 40ff Google Scholar; Ohlin, J, ‘Targeting and the Concept of Intent’ (2013) 35(1) MichJIntlL 79, 82ffGoogle Scholar.

⁶⁷ ILC Commentary to art 16, para (1) (emphasis added).

⁶⁸ ibid para (5) (emphasis added).

⁶⁹ In the Bosnian Genocide case (n 13), the ICJ considered art 16 by analogy with the complicity provision in the Genocide Convention in the context of its consideration of the mental element, suggesting some read across between these different areas of law is permitted.

⁷⁰ Rome Statute of the International Criminal Court, open for signature 17 July 1998, entered into force 1 July 2002; UNTS Vol 2187 No 38544.

⁷¹ Prosecutor v Bemba, Pre-Trial Chamber, ICC-01/05-01/08, Judgment of 15 June 2009 [358].

⁷² ibid [359].

⁷³ Horder, J, Ashworth's Principles of Criminal Law (Oxford University Press 2016) 193 Google Scholar.

⁷⁴ See Quigley (n 30) 111ff for discussion of this and other examples of oblique intent.

⁷⁵ Crawford (n 12) 408, citing Lowe (n 14) 6–9.

⁷⁶ Prosecutor v Bemba (n 67) [363] and [366]. Subjective recklessness requires the assisting State to be able to foresee risk and carry on anyway, whereas objective recklessness is a higher standard, under which the assisting State is negligent regardless of whether it was aware of the risk.

⁷⁷ ibid [363].

⁷⁸ ibid [363–69].

⁷⁹ Crawford (n 12) 408; Jackson (n 5) 160. Nolte and Aust (n 1) 15 note that in some cases ‘a lack of intent can be offset by sufficient knowledge’. Lowe (n 14) 8 argues that ‘As a matter of general principle States must be supposed to intend the foreseeable consequences of their acts.’

⁸⁰ Jackson (n 5) 159.

⁸¹ Quigley (n 30) 111; Gibney, Tomasevski and Vedsted-Hansen (n 57) 294.

⁸² Commentaries (14) and (18) to draft art 27 in the Yearbook of the International Law Commission (1978) Vol II (Pt Two) 99–105.

⁸³ Quigley (n 30) 111; Lanovoy (n 9) 18; Boivin (n 47) 472.

⁸⁴ Aust (n 6) 236, quoting (inter alia) Quigley (n 30) 111; B Graefrath (1996), ‘Complicity in the Law of International Responsibility’ (1996) 2 Revue Belge de Droit International 375; Aust (n 6) 68 cites several authors who consider a requirement of intent to be unworkable. See also Nolte and Aust (n 1) 14.

⁸⁵ On the relationship between intent and knowledge with standards concerning evidence and proof, see further Aust (n 6) 242–3.

⁸⁶ Art 41 of the Articles on State Responsibility (emphasis added).

⁸⁷ Nolte and Aust (n 1) 16.

⁸⁸ Aust (n 6) 343.

⁸⁹ ILC Commentary to art 40 of the Articles on State Responsibility, para (7).

⁹⁰ ILC Commentary to art 41, para (11).

⁹¹ See Aust (n 6) 422.

⁹² See Moynihan (n 7) for strategies and recommendations for governments to reduce the risk of assisting in unlawful acts by other States.

⁹³ For example the judicial review in the UK brought by the Campaign Against the Arms Trade (n 4).

⁹⁴ Moynihan (n 7) ch 4: ‘Strategies and Recommendations for Governments to Reduce the Risk of Assisting in Unlawful Acts by Other States’.

⁹⁵ ibid, paras 158ff.