In Search of Due Diligence Obligations in UN Peacekeeping Operations Identifying Standards for Accountability

It is argued in this article that due diligence, grounded on positive duties under international human rights law, is a standard against which to measure the performance of UN peacekeeping forces. Its adoption by the UN will improve accountability, but in a controlled and principled way. A requirement that the UN act diligently to prevent human rights violations would not impose over-onerous obligations. For responsibility to be incurred an organisation must have clearly failed to take measures that were within its power to take. It is argued that the UN not only should be bound by norms of due diligence but is in fact bound by positive obligations derived from customary international human rights law. The development of some due diligence-type measures by the UN to prevent sexual abuse by peacekeepers and to protect civilians within areas of peacekeeper deployment, and the adoption of an explicit due diligence policy to delineate its relationship with non-UN security actors, are positive signs. Howev-er, the article demonstrates that the UN needs to further internalise and develop its due diligence obligations if it is to limit human rights violations committed under its watch. Furthermore, it needs to create accountability mechanisms to ensure that it develops the rather limited measures taken thus far, including provision for victims to be able to hold the organisation to account for failure to protect them from human rights violations. Only by accepting its responsibility and liability to such victims will be the UN be driven to improve its due diligence when mandating, preparing, training, deploying and directing peacekeeping operations.


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Introduction** In a sense arguments over the immunity and accountability of the UN have obscured the ongoing uncertainty over the primary and secondary rules of international law applicable to the UN when undertaking peacekeeping. It is necessary to understand what violations of international law have been committed by the UN before any attempt is made to assess whether immunity should prevent access to justice before national courts and whether alternative methods of settlement are required. Accountability generally improves in response to pressures exerted or released after or during crises or scandals.1 However, the UN seems to be inured to such pressures. Sexual abuse and exploitation (sea) by peacekeepers continues as do failures to take adequate measures to protect civilians from violence in areas where peacekeepers are deployed. The UN has hidden behind its cloak of immunity when faced with mass claims arising from the genocide in Srebrenica and from the cholera epidemic in Haiti. Moreover, it has failed to stop the epidemic of sea that runs across UN peacekeeping operation like an open sore. The scandals and crises attached to these human rights violations do not seem to have improved the UN's accountability. The fear of exposure to mass claims only partly explains the UN's continued reliance on absolute immunity as provided by the Convention on Privileges and Immunities 1946, and its reluctance to establish the type of claims commissions delivering nonjudicial redress promised in every peacekeeping status-of-forces-agreement (sofa) but never delivered.

Due Diligence as a Standard
One solution to the lack of clarity in the primary and secondary rules applicable to the UN is to recognise that due diligence is applicable to the UN. In general, due diligence 'has become a short hand reference to a set of criteria for assessing the level of care' provide by state authorities,3 and it is argued here other international legal persons whose actions impact upon individuals. More specifically this signifies that the UN should take care to ensure that those actors it has mandated and over whom it exercises authority do not act in a way that causes damage, injury or loss, or fail to act to prevent damage, injury or loss, especially when that is a result of their internationally wrongful conduct. Due diligence obligations are found in various areas of international law,4 but are particularly developed in international human rights law as a result of the positive obligations placed on states to ensure the protection of human rights of individuals within their jurisdiction. Under international human rights law a state's 'obligations in relation to the actions of third parties are often expressed in terms of due diligence' , meaning that the state can be 'held liable for human rights violations caused by a third party where the state has failed to exercise due diligence to prevent the violation or to respond as required' .5 Extending this standard to the UN entails accepting the premise that the UN is bound by customary international law and that positive obligations are found in customary human rights law or, indeed, are emerging as customary norms, given that the UN is not a party to the human rights treaties which contain such positive duties. These issues will be returned to. Furthermore, extending due diligence to the UN as a legal obligation also depends upon whether the UN exerts sufficient authority and control in a host state through its peacekeeping force for human rights obligations to attach to it. On the latter point, the Human Rights Committee felt that the obligations of troop contributing nations (tcns) to ensure the human rights of individuals within their power or control applied extraterritorially when their troops formed part of a peacekeeping mission.6 These are treaty obligations of tcns drawn from the International Covenant on Civil and Political Rights, but it is argued that their customary equivalents apply to the UN as an international legal person having rights and duties under international law and exercising authority and control over individuals through its peacekeepers.7 This would mean that if the UN does not act diligently to prevent human rights violations when it has the power to do so then it would be responsible and accountable to those suffering harms as a result of those violations. If the UN does not waive its immunity before domestic courts when faced with claims arising from its failures, it will have to establish alternative methods of settlement. Placing its conduct within a human rights due diligence paradigm will, it is argued, put genuine pressure on the UN either to reform itself regarding immunity and dispute settlement or face the consequences of its intransigence. If the UN remains unchanged then the possibility arises of domestic courts and host governments being less amenable to its stance on immunity. Host states often desperately need UN assistance but not at any cost. It is argued that the adoption of due diligence as a standard against which to measure the performance of UN peacekeeping forces will improve accountability, but in a controlled and principled way.8 A requirement that the UN act diligently to prevent harm being caused by human rights violations would not impose over-onerous obligations. For responsibility to be incurred, it must be demonstrated that the UN had 'manifestly failed to take all measures' that were 'within its power' to take.9 It is argued that the UN not only should be bound by norms of due diligence but is in fact bound, although disputes about the nature and extent of such obligations remain to be fully resolved. Nevertheless, reflecting its position as a leading human rights norm creator and promotor, the UN needs to internalise these norms as a first step towards empowering victims to hold the organisation to account if it manifestly fails to protect them from human rights violations when it had the power to do so.

An Appropriate Normative Framework for Peacekeeping
Due diligence is argued to be an appropriate way to view the UN's human rights obligations. This is because the UN itself does not directly perform Viewing a peacekeeping operation in principle as a subsidiary organ of the UN does not override the fact that such an operation is made up of separate state organs in the form of contingents from tcns, each operating within a defined area of deployment, and each with their own command and disciplinary structures.24 Although the UN has 'operational authority' over peacekeeping through the Secretary General and Force Commander,25 this does not guarantee effective command and control of the conduct of peacekeepers on the ground. Evidence that the use of the so-called 'Red Card' whereby a tcn commander may refuse to follow orders issued by the UN Force Commander after consulting with his government is readily found.26 Given the proscriptive nature of a state's military law and the hierarchical nature of national command structures, it can be presumed that soldiers are operating under national command and national rules of engagement (RoE) for at least some of the time while serving in international military operations, including blue-helmeted UN peacekeeping operations,27 despite the development of clearer RoE at UN level.28 This leads to an accountability gap or, more accurately, an accountability dilemma between the UN's authority and overall command over peacekeeping operations and the tcns' day-to-day control of peacekeepers. The dilemma is that the UN ought to have human rights duties and not just the tcn for practical and ethical as well as legal reasons. If it were just tcns that bore responsibility for human rights violations by their troops while on peacekeeping duty, then tcns would either operate mostly outside the UN command structure or would cease to contribute troops for fear of liability. This dilemma can be international responsibility and the law of international organizations: Managing concerns over the attribution of UN peacekeepers' conduct to troop-contributing nations' , addressed by arguing that the UN has due diligence obligations in regard to the conduct of peacekeepers it has set in train. Peacekeepers remain soldiers of their sending states but they are also peacekeepers acting for the UN,29 meaning that the UN should be diligent to ensure that peacekeepers operate within an institutional and procedural framework that includes respect for, and protection of, the human rights of the civilian population of the host state. In this way due diligence can fill a gap in an 'era of "privatized" international relations' ,30 because although the UN may not effectively control all of the activities carried out under its authority, it still owes a duty of due diligence to those affected by such activities.
Although at this stage this remains an abstract contention -to the effect that the UN, as an international actor deploying armed forces with the concomitant potential for both harm and for preventing harm, ought to be bound by obligations of due diligence in a moral sense -it will be argued below that the UN is also bound in a legal sense. The purpose of this section is to establish that due diligence provides an appropriate standard against which to judge the UN in performing its peacekeeping function. The application, acceptance, and implementation of human rights due diligence obligations in UN peacekeeping operations are considered in section 5 below. There is limited and uneven evidence of the development of standards and measures by the UN that would fit the meaning and purpose of due diligence, although there are very few instances of due diligence being used as a term within the UN (with the exception of the quite narrowly conceived Human Rights Due Diligence Policy adopted in relation to non-UN security forces).31 Nonetheless, the contention in this article is that due diligence obligations are applicable to the UN as primary rules of international law supported by secondary rules of responsibility.32 This position is developed in the following section. As an international legal person, a status implied from the provisions of the UN Charter indicating the organisation's autonomy from member states, the UN possesses separate rights and duties on the international plane.37 More substantively, the International Court of Justice has declared that the UN is a subject of international law and as 'as such' is 'bound by any obligations incumbent upon' it 'under general rules of international law, under their constitutions or under international agreements to which' it is a party.38 Verdirame concludes that 'the most plausible interpretation' of the term 'general rules of international law' used by the Court is that it is shorthand 'for customary international law of universal or quasi-universal applicability and for general 33 Jan principles of law' .39 However, a strict consensual view of international law at least casts doubt upon the automatic attachment of customary human rights duties to the UN without its subsequent express or tacit consent,40 although the orthodox position is that unless a state is a persistent objector customary international law is binding on all states,41 and this arguably should apply to the UN. Nevertheless, while international legal personality gives the UN the capacity to hold duties and rights, the actual possession of specific obligations including ones of due diligence remains uncertain until the UN internalises these obligations. In general terms, it would be crippling for the legitimacy of the UN for it to deny that it is bound by the external rules of the international order it has helped to create, moreover a legal order that it is at the heart of. As stated by Verdirame, it would 'be extremely disruptive for the international system to tolerate the presence of actors that are endowed with legal personality, and thus with the legal capacity to operate upon the international plane, but are exempt from a body of universally or almost universally accepted rules' .42 In identifying the applicability of human rights law to peacekeeping operations 'regardless of the character of the situation' to which the force is deployed, the authors of the Leuven Manual identify that the primary source of obligation on the UN when performing its peacekeeping function is found in customary human rights law.43 Nevertheless, there remains uncertainty regarding the existence of positive obligations under customary human rights law. John Cerone captures the problem in stating that it is unclear whether the positive treaty obligations in Article 2(1) of the International Covenant on Civil and Political Rights have counterparts in customary international law. However, having said that he accepts the application of such obligations to the UN at least when it is exercising sovereign powers over a territory as it did exceptionally in Kosovo.44 Although most modern peacekeeping operations do not exercise a full range of sovereign powers, they do regularly use a lesser range of public powers (using force to protect civilians and to tackle spoilers, powers of arrest and detention, as well as a range of public order powers).45 It is argued here that when performing these functions peacekeeping forces as subsidiary organs of the UN are bound by positive obligations of human rights law, requiring them to exercise due diligence in protecting the human rights of civilians under their authority or within their power.46 In summary, due diligence obligations attach to the UN in regards to its peacekeeping operations, either by dint of customary rules of international law applicable to it as an international legal person, or, secondly, as the analysis in the remaining sections show, via its own internal constitutional order and the rules deriving from it.47

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The Decides that the mandate of unmiss shall be as follows, and authorizes unmiss to use all necessary means to perform the following tasks: (a) Protection of civilians: (i) To protect civilians under threat of physical violence, irrespective of the source of such violence, within its capacity and areas of deployment …(ii) To deter violence against civilians, including foreign nationals, especially through proactive deployment, active patrolling … in particular when the Government of the Republic of South Sudan is unable or failing to provide such security; (iii) To implement a mission-wide early warning strategy, including a coordinated approach to information gathering, monitoring, verification, early warning and dissemination, and response mechanisms, including response mechanisms to prepare for further potential attacks on United Nations personnel and facilities; (iv) To maintain public safety and security within and of unmiss protection of civilians sites; (v) To exercise good offices, confidence-building, and facilitation in support of the mission's protection strategy, especially in regard to women and children …; (vi) To foster a secure White 214 journal of international peacekeeping 23 (2020) 203-225 doctrine and practice on due diligence do not demonstrate a clear acceptance of external due diligence obligations arising under international human rights law. This is especially so given that there are some instances in peacekeeping practice where due diligence should apply to the UN, but the UN does not appear to accept it has obligations in this regard. The failure to take measures to prevent cholera in Haiti seems to be a breach of a duty of care by the UN and a lack of due diligence to take measures to protect the rights of the population of Haiti. While discussion of Haiti has been largely about the legality and legitimacy of the UN's use of immunity to protect itself from national courts,49 the failure to screen or to ensure the screening of the contingent from Nepal and to ensure that proper sanitation was installed in the camp by private contractors engaged by minustah,50 demonstrate that the UN did not achieve the requisite level of care in fulfilling its obligations to respect and protect the life and health of the people of Haiti. Nevertheless, the UN has only accepted 'moral responsibility to the victims of the cholera epidemic in Haiti' ,51 indicating that there is still a long way to go towards the UN fully accepting that it is bound by legal obligations of due diligence. The UN's ability to protect itself from national courts by invoking its immunity may be called into question in future cases following a recent judgment of the US Supreme Court. In Jam v International Finance Corporation (ifc), the US Supreme Court dismissed the ifc's reliance on absolute immunity in the face of a mass claim brought by victims of environmental and health damage caused by the negligent construction of an ifc financed power station in India. The potential impact of this judgment on the UN's continuing reliance on absolute immunity to protect its independence from states is unclear.52 Adapting a form of restrictive immunity to the UN would suggest that, if the Supreme Court's approach takes hold in the jurisprudence of national courts, the UN's claim to immunity in a case like Haiti might not be upheld by those courts. The environment for the eventual safe and voluntary return of internally-displaced persons (idps) and refugees including, where compatible and in strict compliance with the United Nations Human Rights Due Diligence Policy (hrdpp), through monitoring of, ensuring the maintenance of international human rights standards by, and specific operational coordination with the police services in relevant and protection-focused tasks, in order to strengthen protection of civilians' -UN Doc distinction drawn in sovereign immunity claims between sovereign and commercial acts is not automatically applicable to the immunity of the UN.53 However, as has been said the UN does exercise public powers in the performance of its peacekeeping functions, for instance the power of detention,54 the right to use potentially lethal force, and sometimes lawmaking making powers as in Kosovo.55 These should continue to be covered by the organisation's immunity, but in acts outside of that, for example in engaging private contractors to construct sanitation facilities for peacekeepers, the arguments for immunity to protect the UN's ability to perform its functions do not appear convincing. Indeed, the justification for invoking immunity in these circumstances seems to be to prevent crippling damages being awarded against the UN. Nevertheless, the absolute form of immunity seemingly found in the Convention on Privileges and Immunities 1946, Article 2, remains a massive, possibly insurmountable obstacle given the caveats found in the Supreme Court's judgment,56 and the UN's consistent invocation of such immunity when faced with mass claims against it. Despite significant inconsistencies in practice, and the obscuring effect of assertions of immunity by the UN, which even if accepted do not absolve the UN from responsibility, UN peacekeeping doctrine indicates acceptance by the UN that it must take at least some measures to respect and protect human rights. However, the resultant due diligence framework remains quite basic. In particular, the UN's duties towards individuals remain underdeveloped. As a duty bearer the UN's due diligence not only extends to taking measures to ensure that tcns comply with their human rights obligations to protect the rights of individuals within their jurisdiction, but also means that the UN owes duties of due diligence to the rights holders, namely individuals within its power. In terms of internalising due diligence obligations there is more evidence that the UN is increasingly accepting its due diligence obligations towards tcns, but is more reluctant to accept that it has due diligence obligations towards individuals in the host state. The UN may contract its peacekeeping function to tcns, but their soldiers are present in a host state as UN peacekeepers, which means that the UN's duties to ensure that its peacekeepers do not violate human rights cannot stop at the level of UN-tcn relations but must extend in principle to the population of the host state. In practice, those due diligence obligations will only be triggered where the UN has the power to prevent abuse of individuals within the host state's population.
It is worth noting that in its 2018 resolution on 'United Nations Peacekeeping Operations' the Security Council affirmed its support for the 'development of a comprehensive and integrated performance policy framework that identifies clear standards of performance for evaluating all United Nations civilian and uniformed personnel'; while urging that all tcns 'meet UN performance standards for personnel, training, and equipping' .57 There is a drive by the UN to improve peacekeeping performance and management but the question remains as to how that might translate into meaningful due diligence obligations.58 It is also questionable whether UN practice is heading towards the implementation of due diligence obligations in a human rights law sense, or whether it is developing a doctrine of due diligence more akin to that used in the business community: 'due diligence is normally understood to mean different things by human rights lawyers and by business people … human rights lawyers understand due diligence as a standard of conduct required to discharge an obligation, whereas business people normally understand due diligence as a process to manage business risks' .

Sexual Exploitation and Abuse (sea)
The Secretary General's 2003 Bulletin on sexual abuse exhibited some due diligence characteristics in that it was directed at providing measures of protection for individuals from sea by UN peacekeepers. The Bulletin states that the Head of Mission 'shall be responsible for creating and maintaining an environment that prevents sexual exploitation and sexual abuse, and shall take appropriate measures for this purpose' . In particular, the Head of Mission 'shall inform his or her staff of the contents of the present bulletin' .61 Furthermore, the Bulletin provided a limited form of due diligence in relation to third parties but specifically when the UN has entered into arrangements with them, by providing that UN officials shall inform them of the standards of conduct, and 'shall receive a written undertaking from those entities or individuals that they accept these standards' . Furthermore, it stated that the 'failure of those entities or individuals to take preventive measures against sexual exploitation or sexual abuse, to investigate allegations thereof, or to take corrective action when sexual exploitation or sexual abuse has occurred, shall constitute grounds for termination of any cooperative arrangement with the United Nations' .62 However, in large part, the 2003 Bulletin restricted appropriate due diligence measures of prevention to informing peacekeepers of the contents of the Bulletin. In terms of remedies, the possibility of referral to national prosecuting authorities,63 is insufficient given the normal weaknesses of the host state's criminal justice system and the unwillingness of tcns to punish offenders. Of further concern are the limited preventive measures to be taken when engaging non-UN entities, which are restricted to duties of informing such entities of the standards, and termination of the arrangements if those entities fail to comply with those standards.
Due to the serious problem of on-going sea by peacekeepers the UN has increased its preventive measures, particularly in the form of the screening of peacekeepers.64 Bearing in mind the introduction of cholera into Haiti by None of these initiatives or measures, however, indicate that the UN is prepared to accept responsibility for a failure to prevent sea by its peacekeepers. Indeed, the UN does not accept liability for the off-duty acts of its peacekeepers.66 However, as Athena Nguyen points out: 'conduct such as sea may not be provided for in the rules of the organisation but this does not necessarily exempt the UN from responsibility' .67 Furthermore, 'this argument may be even stronger for conduct that is systemic, widespread, and ongoing, as acts of sea by UN peacekeeping personnel appear to be' .68 Article 8 of ario 2011 provides that the ultra vires conduct of an 'organ or agent' is an act of the UN 'if the organ or agent acts in an official capacity and within the overall functions of that organization' .69 While this may mean it is difficult to attribute sea conduct directly to the UN because it is committed in private, the UN remains responsible for its own failure to prevent sea conduct from being committed by peacekeepers. After examining the ilc's Commentaries on this aspect of the ario, Ngyuen states that 'the mere fact that the conduct was undertaken in an off-duty capacity does not necessarily exclude the responsibility of the international organisation if the conduct breached an obligation of prevention that may exist under international law' .70 Nguyen concludes that the UN 'may still bear responsibility for the conduct of its peacekeeping personnel if the "off-duty" misconduct breached the UN's positive obligations to prevent this misconduct' .71 However, as Ferstman relates, UN practice has fallen considerably short of this: 'the UN does not see itself as having any obligation to entertain claims concerning its own liability for sexual exploitation and abuse allegations which occur under its watch; instead, it has carved out a much more limited role for itself -supporting efforts of troop contributing countries to investigate and prosecute criminal allegations and encouraging states to address paternity and child support claims, and to explore the possible use of ex gratia payments to victims' .72 In other words the UN has taken some tentative steps to recognising that it has due diligence obligations in its relations with tcns, but not so in relation to victims of peacekeeping sea.

The Protection of Civilians
At a general level the UN's due diligence obligations to ensure respect for human rights by peacekeepers include the adoption of measures such as clear rules, training, education, risk assessment and mitigation, but also to ensure a peacekeeping force has adequate resources and the capabilities to fulfil its mandate.73 More specifically, the ambit of due diligence extends to require that the UN puts in place reasonable measures to ensure that peacekeepers actively protect the human rights of civilians in their areas of deployment from violation by non-UN actors. Such measures, scattered unevenly and not always convincingly in UN doctrine (for example in Security Council Resolutions, the Brahimi Report, Capstone Doctrine, and the Report of the High Level Independent Panel on Peace Operations), include proactive patrolling, rapid redeployment, adequately protected safe havens, intercessions, detention of individuals on security grounds, and the use of potentially lethal force where absolutely necessary to protect the lives of civilians and peacekeepers.74 A detailed analysis of key UN documents to uncover indications of whether these measures could be said to flow from duties of due diligence has been undertaken elsewhere. 75 The purpose here is to try to understand whether it is possible to identify a due diligence obligation on the UN to protect civilians, and to consider the implications of a failure to fulfil that obligation. According to Willmot and Sheeran the 'most important rights' for the protection of civilians in peacekeeping 'include the right to life, the prohibition against torture and ill-treatment, and the freedom from arbitrary detention' . However, in terms of the duty bearer, Willmot and Sheeran point to the host state as the main actor when stating that '[t]hese are human rights that any host state will have an obligation to respect and ensure respect for (that is, a positive obligation), including by non-state actors' .76 They concede that the application of human rights law 'to UN peacekeeping operations is difficult to contest' , although they state that 'the precise content of these obligations' is unclear: '[t] he UN is not party to human rights treaties and the greatest difficulty lies in understanding the scope and extent of obligations for a UN force, which has no sovereignty over a territory and has lesser powers than a state' . 77 However, this understates the growth in public powers exercised by the UN in its modern stabilisation-type peace operations.78 As Alexander Guilder has written such forces 'are mandated to support the extension of state authority';

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In Search of Due Diligence Obligations in UN Peacekeeping journal of international peacekeeping 23 (2020) 203-225 'they operate alongside state forces and actively build the capacity of those forces'; 'they use varying degrees of proactive, robust force to prevent attacks on themselves and those they are mandated to protect'; and 'lastly, they have mandates to support (re)establishing the rule of law' .79 More specifically such forces exercise powers of arrest, detention and regularly use potentially lethal force,80 which can cross the threshold into the sort of protracted armed violence that triggers the application of international humanitarian law to such forces.81 In such conditions of violence, Willmot and Sheeran identify a potential positive or due diligence obligation on the UN 'to ensure respect' for international human rights law 'by others such as non-state actors, private individuals and even local authorities' .82 This signifies that 'a failure to intervene may also violate' the human rights obligations 'owed by UN peacekeepers to the host state's population' . 83 In the extreme instance of the loss of life at Srebrenica, the victims' families succeeded in a claim against the troop sending state of the peacekeepers (The Netherlands),84 the UN being protected from liability by its immunity before national courts.85 However, the Netherlands' Supreme Court ultimately decided that the liability of the Netherlands was for the conduct of peacekeepers under the effective control of the state rather than the failure to take measures to prevent genocide. 86 In this way, the Court managed to restrict the Netherlands' liability to 10%,87 when the adoption of a White 222 journal of international peacekeeping 23 (2020) 203-225 due diligence standard would have suggested a greater proportion, moreover that such responsibility should be shared with the UN.

The UN's Due Diligence Policy of 2013 and Non-UN Forces
The UN's Due Diligence Policy of 2013,88 in which the UN undertakes to implement measures to ensure that non-UN forces it supports are not committing war crimes, is a step forward in the sense that it expressly recognises due diligence can be applicable to the UN. The Policy expressly accepts the UN's due diligence obligations in relation to non-UN forces, but arguably it also opens the door to more general positive obligations to take measures to prevent and respond to violations by third parties by accepting the applicability of human rights law, international humanitarian law and refugee law to the UN.89 The wider import of the Policy is found in the statement that: '[a]dherence to the human rights due diligence policy is important to maintain the legitimacy, credibility and public image of the United Nations and to ensure compliance with the Charter and with the Organization's obligations under international law' .90 The Policy accepts that the UN must take precautions to assess the risk of violation and respond to violations by non-UN forces it supports, including intercession with the entity in question and if necessary the removal of support. Specifically when the UN is contemplating involvement with non-UN security forces it 'must therefore pursue a policy of due diligence' consisting of: an assessment of 'the risk of the recipient entity committing grave violations of international humanitarian law, human rights law or refugee law'; 'transparency with receiving entities about the legal obligations binding the Organization and the core principles governing provision of support'; and an 'effective implementation framework' including procedures for monitoring compliance and interceding.91 Standing alone this represents a positive and explicit development towards accepting that the UN has human rights due diligence obligations to take a series of precautionary, preventive and responsive measures to ensure that a state or non-state security actor working alongside UN peacekeepers does not commit grave violations of human rights or other international norms. This 88 'Human rights due diligence policy on United Nations support to non-United Nations security forces' , UN  Policy establishes that the UN owes due diligence obligations in its relationships with non-UN security actors. However, its adoption by the UN raises the question of the UN's wider due diligence obligations to the host population to take positive measures through its peacekeepers to address potential or actual abusive actions committed by any violent non-UN actor who operates in areas to which peacekeepers are deployed.

Conclusion
This contribution has focused on the application, acceptance, and implementation of human rights due diligence obligations in UN peacekeeping operations. It has concentrated on identifying the applicability of primary rules of due diligence to the UN. This article has pointed to growing evidence of the development of standards and measures by the UN that would fit the meaning and purpose of due diligence, although there are very few instances of due diligence expressly being used as a term within the UN. This is not to say that such obligations are not applicable to the UN. It has been argued that due diligence obligations are applicable either through customary human rights law, or the internal law of the UN, or both. The development of measures such as screening peacekeepers, blacklisting tcns with poor track records in preventing and/ or punishing perpetrators of sea, are designed to prevent peacekeepers from doing harm. 92 As well as measures to prevent abuse by peacekeepers, the contribution has identified a number of positive measures in UN peacekeeping practice designed to reduce loss of civilian life or other serious human rights violations of the host state's population including: proactive patrolling, weapons training, temporary and reviewable preventive detention, protection of UN compounds and camps, the identification of threats and risks and strategies to address these, including addressing the 'risk averse' approach of many tcns. 93 Responsibility for human rights violations caused by the failure to adopt and carry out these measures should be shared between the tcns and the UN,94 and oversight should be secured by an independent review process 225 In Search of Due Diligence Obligations in UN Peacekeeping journal of international peacekeeping 23 (2020) 203-225 substantive positive human rights obligations the UN owes to rights holders especially civilians within the host state, and identifies the measures that can reasonably be taken by the UN and its peacekeepers to ensure those rights are protected given the inherent limitations in the way forces are structured. Only by starting with the rights of vulnerable people can a human rights law approach to the due diligence obligations of the UN be realised. Put simply, when the UN promises to protect civilians in countries to which it deploys peacekeepers it needs to take care to ensure that this happens. As stated in the Brahimi Report 2000, with reference to the failure of peacekeeping in Rwanda: 'peacekeepers -troops or police -who witness violence against civilians should be presumed to be authorised to stop it, within their means, in support of basic United Nations principles and . . . consistent with the "perception and the expectation of protection created by [an operation's] very presence"' .98 98 Brahimi Report, supra note 74, para. 62, citing the Report of the Independent Inquiry on Rwanda UN Doc. S/1999/1257, 15 December 1999, p. 51.