Abstract
Despite increasing recognition of the intersections between human rights and environmental protection, relatively little attention has been paid to the use of international environmental law in the interpretation of human rights law by UN human rights bodies. This article examines how and to what extent international environmental standards may be used in the interpretation of human rights by UN bodies, utilising the legal interpretive method of systemic integration under Article 31(3)(c) of the Vienna Convention on the Law of Treaties 1969, with a particular focus the recent Torres Strait Islanders case before the Human Rights Committee. The article analyses the situations in which systemic integration may be used to integrate environmental standards in the interpretation of human rights and concludes with some evaluative reflections on the use of systemic integration in this context, the advantages, disadvantages, limitations, and implications.
Keywords
INTRODUCTION
We live in a world that is struggling with multiple multifaceted environmental crises. It is thus unsurprising that the intersection between human rights and the environment has become such a burgeoning area of scholarship, lawmaking, and litigation. Despite all this attention, one aspect of this picture has largely escaped the limelight: the systemic integration of environmental standards in the interpretation of human rights law.
At first glance, such a prospect holds important potential. Human rights norms are famously ‘open-textured’, 1 vaguely formulated, and flexible in their content so as to be adaptable to changing circumstances. They thus rely heavily on the process of interpretation and application to determine their concrete content in a particular case. Human rights claims, particularly in environmental harm contexts, often revolve around whether the State in question did enough to comply with their positive obligations under the trifecta of ‘respect, protect, and fulfil.’ 2 Whether conceived of as ‘appropriate steps’ 3 or due diligence, 4 this facet of human rights obligations essentially amounts to the standard to which a State should be held. In certain contexts, one could see this as an international environmental law-shaped hole, waiting to be filled.
In accordance with Article 31(3)(c) of the 1969 Vienna Convention on the Law of Treaties (VCLT), ‘there shall be taken into account […] any relevant rules of international law applicable in the relations between the parties.’ 5 There is thus a mechanism for such integration. Indeed, this specific mechanism was raised recently before the Human Rights Committee (HRC) in the case of Billy v. Australia, henceforth referred to as the Torres Strait Islanders case. 6 There it was argued by the applicant that Australia's obligations under the Paris Agreement on climate change should be taken into account in the interpretation of the applicants’ rights under the International Covenant on Civil and Political Rights (ICCPR). 7 The issue was left unresolved by the HRC.
Against this background, this paper evaluates the prospects and utility of integrating international environmental law in the interpretation of human rights. It focuses on the UN treaty bodies, in part because of their global reach and in part because the role of these bodies in relation to systemic integration has been the least explored in the literature, and it is thus where the most uncertainty lies. 8 The paper begins by establishing the legal framework under Article 31(3)(c) of the VCLT, the different elements required for this method of interpretation, and the applicability of this legal framework in the context of the UN human rights treaty bodies (Section 2). Section 3 then turns to the specific question of whether, how, and to what extent international environmental law standards could be integrated into UN human rights standards, both in the specific context of climate change (as raised in the Torres Strait Islanders case) and more widely. It also offers some evaluative reflections on the utility and potential risks of this method of interpretation.
LEGAL FRAMEWORK UNDER THE VIENNA CONVENTION
Article 31(3)(c) and Systemic Integration
The key rule of interpretation for present purposes is found in Article 31(3)(c) of the VCLT: ‘There shall be taken into account, together with the context […] any relevant rules of international law applicable in the relations between the parties.’ 9 This Article codifies the principle of systemic integration within international law. 10 This rule of interpretation is based on the understanding that ‘treaties are themselves creatures of international law’; 11 no treaty rule may be fully understood in a vacuum, but must instead be read alongside the broader tapestry of international law. 12
Article 31(3)(c) itself operates within the broader interpretive system outlined in Articles 31 and 32 of the VCLT. It must thus be read alongside the other elements of Article 31, including the general rule of interpretation in Article 31(1), namely 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.’ 13 According to the International Law Commission's (ILC) commentary to the earlier version of this Article, the three paragraphs of Article 31 are intended to operate as ‘a single combined operation’. 14 This implies the absence of a hierarchy between the different paragraphs of Article 31 as such. 15 The phrasing ‘shall be taken into account’ implies that reference to external legal rules is not determinative to the interpretation at hand, but merely a factor to be applied alongside the other elements of Article 31. In some situations, it may play a very minor role or no role at all: it will not always be necessary or appropriate to refer to the broader corpus of international law, especially where the ordinary meaning of the terms is clear. 16 In other cases, such as where there is a potential normative conflict between the rule under interpretation and other relevant rules of international law, Article 31(3)(c) will carry more weight. In any case, where there is doubt, and where other rules of international law can lend a hand and provide an interpretive aid in addition to the context, this can (and indeed must) be taken into account. 17
The Elements of Article 31(3)(c)
Relevant Rules of International Law
The first part of Article 31(3)(c) refers to ‘any relevant rules of international law’. 18 The word ‘rules’ would seem to refer to legally binding provisions of international law, and not ‘broader principles or considerations’ 19 or non-binding instruments commonly referred to as ‘soft law’. 20 This would therefore include legally binding provisions found within treaties, customary international law, and general principles of international law. 21 That being said, it has been highlighted 22 that international judicial bodies have at times referred to non-binding instruments such as the UN Universal Declaration on Human Rights and the ILC's Articles on State Responsibility as interpretive aids. 23 These should, however, be treated as exceptions, or as shorthand for parallel customary international law rules.
The other side of this element is the relevance criterion. What makes particular rules ‘relevant’ in this context? It is an undeniably ‘vague’ condition 24 which appears to leave room for a multitude of different factors which may have a bearing on the relevance of particular role in a particular context. An external rule will clearly be relevant if it was created (most likely in the context of the treaty) to ‘solve the same or similar factual, legal or technical problems’; 25 in other words, when the external rule and the treaty rule under interpretation share a common purpose and/or subject matter. It may be extrapolated from this that an external rule may also be relevant when it shares such similarities with the present application of the treaty rule under interpretation, and not simply the treaty rule as written or originally envisaged. This is a particularly important distinction when it comes to more open-textured, evolutive regimes. Beyond this, other factors to be taken into account when determining ‘relevance’ include, first, whether the external legal rule can actually help to clarify the meaning of the rule under interpretation (that is, whether its substance sheds any further light on how the interpreted rule should be understood) and, second, whether the object and purpose(s) of the treaty under interpretation generally align with those of the external instrument. 26
Applicable Between Which Parties?
One of the more controversial aspects of Article 31(3)(c) is the precise meaning of the phrase ‘applicable in the relations between the parties’. 27 The key question here is the identity of the parties to which the Article refers: does it relate to all parties to the treaty under interpretation (restrictive approach), or only the parties to a particular dispute over interpretation of that treaty (broader approach)? When the treaty under interpretation is a large or even global multilateral regime, the answer to this question has the potential to severely limit the application of systemic integration under Article 31(3)(c). In such a case, if Article 31(3)(c) refers only to rules applicable between all parties to the treaty, then only treaty rules emanating from similarly large or global multilateral regimes whose membership included all parties to the interpreted treaty would fall under its scope as potential interpretive aids (in addition, of course, to customary international law and general principles). 28
It has been suggested that, for this reason, the restrictive approach may be too limiting, particularly in the context of large multilateral or universal regimes. 29 It is also true that some practice would appear to support this approach, such as the International Court of Justice's (ICJ) decision in Certain Questions of Mutual Assistance. In that case, the Court explicitly referred to Article 31(3)(c) 30 and found that a bilateral treaty between the parties did ‘have a certain bearing on the interpretation and application of’ the multilateral treaty at issue, namely the 1986 Convention on Mutual Assistance in Criminal Matters. 31
However, there are a number of problems with this approach. For one, it presupposes the existence of a dispute over interpretation. The rules on interpretation in the VCLT are not only designed for use by adjudicative bodies in the context of a dispute, but also for States and other actors to determine the meaning of treaty provisions independently of a particular situation or application. 32 It would therefore not be in keeping with this purpose for Article 31(3)(c) to refer only to the parties to a dispute over interpretation when such a dispute may not exist. Second, in a multilateral treaty, especially one which expresses obligations erga omnes partes, following the broader approach could lead to normative incoherence and a lack of uniformity with regard to the obligations of different States within the treaty. 33 It would mean that the range of treaty rules available as interpretive aids would change depending on which parties to the same treaty were in dispute over its interpretation. Further, Linderfalk has convincingly argued that the ordinary meaning of the text in Article 31(3)(c), the context in which it is found, and the objective purpose of the VCLT all point towards a more restrictive interpretation of the identity of ‘the parties’. 34
As such, taking the above into account, it seems that the approach most clearly supported by the VCLT and by the principle of the normative coherence of international law is the restrictive approach. Following this approach, ‘the parties’ in Article 31(3)(c) means all parties to the treaty under interpretation.
Intertemporality
The final key question is whether only rules which were applicable (that is, in force between the parties) at the time the text of the interpreted treaty was adopted may be referred to in the context of Article 31(3)(c), or whether ‘the interpreter [may] also refer on occasion to subsequent developments.’ 35 Article 31 contains no clear temporal provision. 36 Nonetheless, a general consensus appears to be emerging in modern scholarship that Article 31(3)(c) may have intertemporal effect, allowing for the use of subsequent legal rules where it appears from the intentions of the parties to the original treaty that the terms therein carry a dynamic or evolving meaning. 37 This may be the case where the terms used are generic, the meaning of which will necessarily change over time, or the instrument itself is established with a view to commit parties to progressive and developing standards. 38
UN Human Rights Bodies and Systemic Integration
In principle, Article 31 of the VCLT applies to all treaties, regardless of their subject matter. 39 However, human rights treaties are sometimes viewed as ‘special’ or ‘self-contained’ regimes, 40 distinct from general international law structures. Although human rights bodies have been known to apply general rules on treaty interpretation, the question remains as to whether all the same rules apply, and with the same conditions and limitations as discussed above in Section 2.2. This seems likely, for several reasons.
First, human rights law is arguably not quite as ‘special’ as it is often made out to be. 41 Human rights treaties are not unique in transcending bilateral relationships between States, 42 in granting rights to individuals, 43 in establishing institutionalised monitoring and compliance systems, 44 or in constituting evolutive normative regimes. 45 Further, there is no clear legal basis to support the contention that general international law rules on treaty interpretation have been dispensed with in the human rights context. It is entirely possible to understand the ‘special’ interpretive rules in the human rights sphere (including, for example, the principle of effectiveness and the principle of evolutive or dynamic interpretation) within the framework of the VCLT. These methods could easily be conceived of as falling under Article 31, including the reference to ‘in light of the object and purpose of the treaty’ and indeed Article 31(3)(c) itself. 46
Further, UN human rights bodies could benefit from the transparency and legitimacy that applying such rules could bring. These bodies occupy a rather precarious place in international law: acting as authoritative interpreters who nonetheless lack the power to generate binding decisions.
47
Even this authoritative interpretation is not always treated as such by other international courts and tribunals.
48
As such, the de facto legal force and impact [of their output] depends on how convincingly and persuasively it is argued, which in turn is largely shaped by the consistent use of an accepted and appropriate method.
49
Systemic integration is utilised as a method of interpretation in certain regional human rights bodies, in some cases with more explicit reference to the VCLT rules than in others. In numerous cases before the European Court of Human Rights (ECtHR), the Court applied the rule of systemic integration with 50 and without 51 explicit references to Article 31(3)(c). In the recent case of Verein Klimaseniorinnen Schweiz and others v. Switzerland, the ECtHR even listed the Paris Agreement and other environmental treaties as relevant international materials for the interpretation of human rights at issue in that case. 52 In the Inter-American and African systems too, there have been applications of this method of interpretation, or at least a very close equivalent. 53
UN bodies have been less active in this regard, but there are still significant indications from a number of these treaty bodies that they consider systemic integration to be part of their interpretive arsenal. In OM v. Ukraine, the Committee for the Elimination of Discrimination Against Women (CEDAW Committee) made reference to the 1963 Vienna Convention on Consular Relations (VCCR) in order to determine the meaning of the term ‘consular functions’, as part of an analysis of whether the State (Ukraine) had violated the applicant's rights under Article 2 of the Convention for the Elimination of All Forms of Discrimination Against Women (CEDAW). 54 In Faure v. Australia, the HRC noted that certain International Labour Organisation (ILO) conventions ‘may be of assistance in elucidating the meaning of the terms’ in the CEDAW (in this case, ‘forced or compulsory labour’). 55 In considering the case of Portillo Cáceres et al v. Paraguay (henceforth referred to as Portillo Cáceres) related to environmental pollution, the HRC ‘observe[d]’ that Paraguay had ratified the Stockholm Convention on Persistent Organic Pollutants and appeared to link this observation with Paraguay's obligation to ‘take all appropriate measures to address the general conditions in society that may give rise to threats to the right to life or prevent individuals from enjoying their right to life with dignity’, including environmental pollution. 56 The HRC did not, however, clarify precisely what influence the Stockholm Convention had on the interpretation of the ICCPR. The only UN body that has explicitly referred to Article 31(3)(c) has been the Committee on the Rights of the Child (CRC) in N.E.R.Á. v. Chile, in which the CRC specifically quoted the rule in Article 31(3)(c) in order to find that ‘the Convention on the Rights of the Child must be interpreted taking into consideration State Parties’ obligations under the Hague Convention [on the Civil Aspects of International Child Abduction].’ 57
Specifically in relation to the climate context, there have been strong indications that the UN bodies view systemic integration as an applicable method of interpretation. In 2019, the HRC noted in its General Comment No 36 the clear connections between human rights and environmental degradation, and that ‘obligations of States Parties under international environmental law should thus inform the content of article 6 of the Covenant’. 58 More recently, the CRC stated that it ‘is mindful of efforts of relevance to its interpretation, including […] the existing and evolving norms, principles, standards and obligations under international environmental law, such as the United Nations Framework Convention on Climate Change (UNFCCC) and the Paris Agreement.’ 59 Even more directly, the Committee on Economic, Social and Cultural Rights drew attention to the insufficiency of State commitments under the Paris Agreement to prevent the most severe impacts of climate change, and noted that ‘[i]n order to act consistently with their human rights obligations, those contributions should be revised.’ 60
Based on the above examples and arguments, it is submitted that, despite a lack of explicit references to Article 31(3)(c) as such, the rules on systemic integration apply to human rights treaties just as to other areas of international law. With this in mind, the next section turns to the interpretation of human rights in light of environmental law.
INTERPRETING UN HUMAN RIGHTS IN LIGHT OF INTERNATIONAL ENVIRONMENTAL LAW
Despite the strong basis for the possibility of applying systemic integration, and despite the recognition that international environmental law can indeed be relevant to the interpretation of UN human rights as established in the previous section, the HRC appeared unwilling to explicitly apply this interpretive method in the Torres Strait Islanders case. Section 3.1. therefore uses this case as an entry point to explore the arguments made in the case, analysing these alongside the rules on systemic integration outlined above. Section 3.2. then broadens the enquiry by considering the implications for the integration of international environmental law in human rights law more generally.
Torres Strait Islanders Case: Integrating the Paris Agreement
The Torres Strait Islanders case concerned a communication made by a number of members of an indigenous minority group, all of whom lived on low-lying islands in the Torres Strait region that were recognised as being particularly vulnerable to the impact of climate change. 61 The authors claimed that Australia had violated their rights under Articles 2, 6, 17, and 27 of the ICCPR due to the State Party's failure to mitigate the impact of climate change and their failure to implement an adaptation programme to ensure the long-term habitability of the islands. 62
The authors of the communication argued inter alia that, in accordance with Article 31(3)(c) of the VCLT, Australia's obligations under international climate change treaties should be viewed as part of the ‘entire prevailing system relevant to the examination of Australia's human rights violations under the ICCPR.’ 63 As such, they argued, these obligations were relevant to interpreting the State's obligations under the ICCPR. 64 This was strongly disputed by Australia, not on the basis that Article 31(3)(c) was inapplicable in human rights cases per se, but because the necessary conditions for its application were not, they argued, met in this particular case. The HRC largely avoided the issue in its Views. It remarked only that the potential ‘appropriateness’ of considering such international agreements was not a bar to the admissibility of the complaint, but was rather an issue for the merits. 65 It did not, however, refer to this point at all during the merits stage. The following subsections examine the different elements of systemic integration in application to this case.
Relevant Rules of International Law
In the original communication, the authors focused on three elements of the Paris Agreement, namely (i) the specific temperature goal of 1.5°C maximum warming; 66 (ii) the obligations related to the setting of nationally determined contributions (NDCs), the determination of which must reflect the State's ‘best efforts’, must be ‘ambitious’, and must reflect the ‘common but differentiated rights and responsibilities’ principle; 67 and (iii) the obligation to ‘pursue domestic mitigation measures, with the aim of achieving the objectives of such contributions.’ 68 The authors of the communication then argued that Australia was in breach of its obligations under the Paris Agreement because the NDC set by Australia did not meet the conditions noted above, and because Australia had taken insufficient action to reduce its emissions. 69
The first of these elements is not strictly speaking a binding rule; rather, it indicates an objective underlying the purpose of the instrument as a whole. In accordance with Article 31(3)(c), it would therefore not be taken into account directly. It may, however, have some indirect influence, since this objective informs the content of the binding obligations in the Paris Agreement, which in turn may be subject to systemic integration. The obligations noted above relating to States’ NDCs are indeed binding rules of international law (even if they may be rather imprecise in the conduct that they require of states), 70 and could therefore in theory operate as interpretive aids.
The remaining question here is whether these rules are ‘relevant’. We saw previously that an external rule is likely to be relevant where it was created to ‘solve the same or similar factual, legal or technical problems’ as the treaty rule under interpretation, 71 where it can substantively serve the interpretive process, and where the object and purpose of the two instruments align.
At first glance, it seems difficult to argue that all these criteria are met in this case. The Paris Agreement was specifically created to respond to the problem of climate change, whereas the ICCPR is a relatively general instrument protecting human rights. 72 Australia argued in their submissions that there were ‘stark differences’ between the two regimes, and thus that the Paris Agreement did not contain relevant rules in the sense of Article 31(3)(c); 73 according to Australia, there was ‘no material relationship between the aims, context and subject-matter of the Covenant and international climate change treaties’. 74 They argued further that ‘it is undeniable that the international community has sought to address climate change primarily, and rightly, as a matter of international cooperation and under international environmental agreements,’ 75 and as such these rules should not form part of human rights litigation.
In response, the applicants referred to the HRC's General Comment No 36 and the Portillo Cáceres case, in addition to jurisprudence from regional human rights bodies, as a basis for the argument that international environmental law is indeed relevant to the interpretation of human rights standards.
76
They argued that: where the type of environmental harm which gives rise to the human rights impact in question is climate change, and the State Party has undertaken international treaty obligations to reduce its contribution to such harms, such obligations are relevant to the interpretation of the State Party's duties under the Covenant in the context of climate change.
77
This would mean that particular external rules may be referred to as relevant rules in some factual situations, but not in others, even if the same human rights norm were under interpretation. This might be criticised on the basis that it introduces uncertainty or a lack of uniformity. That is not true, however. Human rights norms, including those in the ICCPR, are famously open-textured and designed to be applicable to a wide and constantly-evolving range of circumstances. 79 This means that a huge range of external legal rules could cover the same conduct as the human rights norm. A broader approach to relevant rules – one that allows for reference to any of these external rules when they are relevant to the present application of the human rights norm – is entirely in keeping with the logic of Article 31(3)(c). It serves to preserve systemic normative coherence when multiple rules exist which regulate the same or similar conduct.
It would thus appear that Australia's stricter interpretation of ‘relevant’ would place an undue limitation on the application of Article 31(3)(c), particularly in the case of human rights interpretation. This is also broadly supported by the approach taken thus far by the treaty bodies. 80 The Paris Agreement itself explicitly recognises the necessary overlaps between climate action and human rights, implying that it was formulated with at least some of the same or similar factual or legal problems in mind and therefore that there is at least some alignment in the respective objects and purposes of the instruments. 81 Although not addressed in the Torres Strait Islanders case, it might also be noted that there is emerging evidence of the existence of a customary right to a clean and healthy environment. 82 If such a customary right exists, it might be argued that this rule is particularly relevant in the interpretation of human rights in a context of environmental harm.
In this particular case, the applicants argued in part that their rights were violated due to Australia's failure to sufficiently mitigate the impact of climate change on the islands where they reside. The case did thus revolve around the State's obligations to prevent a particular kind of environmental harm, one that is regulated by the Paris Agreement. Taking all this into account, it seems reasonable to conclude that certain rules in the Paris Agreement are indeed relevant in the interpretation of rights under the ICCPR engaged in this case.
Applicable Between the Parties
The next step relates to the identity of the parties to the two treaties under consideration. One interesting element in this case is that the number of parties to the Paris Agreement grew between the original application and the Views, from 185 (184 states plus the European Union) to 195 (194 plus EU) 83 For comparison, there were 173 parties to the ICCPR during the same period. 84
The parties’ submissions are at times slightly confused on this point, partly because they seem to focus on the numbers of parties to the respective instruments, rather than the identity of the parties. 85 The applicant also appears to rely in part on the universal ratification status of the UNFCCC, 86 which is irrelevant to the question of the identity of the parties bound by rules in the Paris Agreement. The key issue here is whether all parties bound by the rule under interpretation (that is, all parties to the ICCPR) are also bound by the relevant rules in the Paris Agreement. The simple answer to this question is no. At the time of the original application, 11 States were party to the ICCPR but not party to the Paris Agreement 87 and by the time the Views were published this number had reduced to 3. 88 Thus, a strict interpretation of ‘applicable in the relations between the parties’ would mean that rules contained within the Paris Agreement would not fall under the scope of Article 31(3)(c). 89 Even applying the broader approach would be tricky here, since not all parties to the dispute are States.
Looking back at the few examples we have of UN treaty bodies applying the rule of systemic integration, the jurisprudence seems to point towards a rather flexible approach to this question. When the CEDAW Committee referred to the VCCR in OM v. Ukraine, 90 the latter treaty had at the time nine fewer parties than CEDAW. 91 It was not clear in Faure v. Australia which ILO instruments the CEDAW Committee found to be relevant since four such instruments in total were mentioned in the Views, 92 but none of them are in force for every single party to the ICCPR. 93 Similarly, a small number of State Parties to the ICCPR are not bound by the Stockholm Convention which was referred to in Portillo Cáceres. 94
It would appear from the above that, despite the logic behind a strict interpretation of the identity of the parties in Article 31(3)(c), the UN human rights bodies (and indeed others) have followed a broader approach. In the case of the human rights bodies, this approach is arguably even broader than that which has been examined in scholarship, since this approach does not even require that all parties to the particular dispute are bound by the external rule in question. This may reflect the particular circumstances of individual human rights complaints, meaning that such cases do not occur between parties as such, but rather between only one party and an alleged victim. It would appear to be a prerequisite that the State Party whose obligations are under interpretation is bound by the external rule. 95 So far, however, the practice of the UN bodies does not suggest any further requirements as to the identity of the parties bound by that rule.
Intertemporality
The question of intertemporality was not raised by the parties in their submissions in Torres Strait Islanders, and thus appeared not to present an issue for either party. It was noted above that, where a dynamic approach to interpretation is appropriate in relation to the particular treaty terms under interpretation, reference may be made to external relevant rules of international law that came into force after the framing of the treaty. International human rights law, with its focus on evolving and adaptive standards and teleological interpretation, 96 is an ideal candidate for such an approach. Human rights standards are intended and expected to change with the times; this presupposes that a dynamic approach is taken to the interpretation. Intertemporality is thus unlikely to be a problem in the context of human rights interpretation.
Taken Into Account
Assuming climate law may be taken into account under Article 31(3)(c), the question remains as to how far and in what ways these roles should influence the interpretive process. One of Australia's main contentions in Torres Strait Islanders was that the applicants’ arguments went beyond the interpretation of ‘rights set forth in the Covenant’ 97 and instead required the HRC to determine the existence of a breach of the Paris Agreement – something well outside the competence of the HRC. 98 The applicants, by contrast, argued that the obligations of Australia under the Paris Agreement essentially amounted to a minimum threshold of conduct necessary to meet the standards within the ICCPR. They submitted, for example, in relation to the right to life: ‘[i]f Australia is in breach of the UNFCCC or the Paris Agreement, it follows that it is also in breach of its obligations under Article 6.’ 99
This is a difficult path to tread: one that runs between the use of an external rule as an interpretive aid and the application of that rule itself. Article 31(3)(c) limits the use of external rules in a number of ways. First, the rule must be ‘taken into account’. 100 This clearly does not extend to the application of an external standard in place of the treaty rule under interpretation. Further, as discussed above, Article 31(3)(c) operates within the broader interpretive system outlined in Articles 31 and 32 of the Vienna Convention. 101 The application of systemic integration as an interpretive method is limited by and balanced against the ordinary meaning of the terms, the context, and the other elements in Article 31(3) where they occur – namely subsequent agreement between parties and subsequent practice. 102
It was noted above that systemic integration is often used where the terms of the treaty under interpretation are unclear or ‘by their nature open-textured’ and thus reference to other international legal rules are likely to be helpful in determining their content. 103 Again, human rights treaties would appear to be an ideal candidate in this regard as they are drafted so as to encompass a broad range of possible applications, are usually comparatively open and vague in their wording, and are designed to be interpreted evolutively. Nonetheless, the role of the external rule remains that of helping to determine content of the human rights standard, rather than replacing it. Could Australia's obligations under the Paris Agreement be understood as a minimum requirement within the context of meeting its obligations under the ICCPR, and thus determinative of their content in that manner? It is often remarked that the standard of conduct required of States by international environmental law is relatively low. In the context of climate law in particular, all binding obligations inevitably stem from a hard-fought compromise, all negotiated in the face of the threat of a ‘race to the bottom’ in terms of emissions commitments. 104 It may at first glance therefore appear sensible to consider international environmental legal standards as a minimum threshold when applying related human rights in certain circumstances – for example, if a State breaches international regulations for the management of hazardous or nuclear waste 105 and this results in death or injury to individuals within that State's jurisdiction, it would seem reasonable to conclude that this conduct would be contrary to the State's human rights obligations.
However, it is essential to bear in mind the different contexts of the two rules under consideration. Systemic integration ‘should be subject to pertinent contextual nuances pertaining to the purpose, function and aims of the other treaty provisions.’ 106 This is supported by the focus on context in Article 31. 107 While the Paris Agreement acknowledges the interaction between climate action and human rights protection, it is designed to counter all problems stemming from climate change through both mitigation and adaptation. By contrast, the rights under the ICCPR are inherently premised upon the basic concepts and values of human rights law including an almost exclusive focus on the individual and on humans rather than the environment more generally. These different contexts do not by any means necessitate conflict between the two instruments, but they do point in different directions. Different interests and values underlie the rules therein. As such, it would be inappropriate to apply the Paris Agreement rules as a minimum threshold per se. The Paris Agreement and other elements of international climate law can only be used to help interpret the particular terms of the human rights norm under consideration, for example to determine the extent to which Article 6 ICCPR requires States to take mitigative measures against climate change to protect the right to life of individuals within its jurisdiction. The interpretive process must be more subtle in nature, and more attuned to the particular context of the individual rights and rules in question.
Finally, it is worth noting that systemic integration is also often used where the terms in a treaty have a well-recognised meaning in another area of international law. 108 This is less relevant in the present situation, as the Torres Strait Islanders case revolved more around interpreting standards than concepts. It will, however, be considered below in relation to systemic integration beyond the Paris Agreement.
Beyond Paris: Systemic Integration, Human Rights, and Environmental Harm
There are a number of key lessons and conclusions which may be drawn from the above discussion of the Torres Strait Islanders case, and which can shed some light on the potential broader use of international environmental legal standards in human rights interpretation. This section highlights and discusses these implications and provides some reflections and evaluation of the advantages and disadvantages of using this method of interpretation.
Lessons Learned for Further Application
Although unfortunately not confirmed by the HRC in Torres Strait Islanders, it was established in the above discussion that the relevance criterion should be based on the relevance that external rule may have to the application of the rule under interpretation in a particular case, rather than on the purposes for which the two rules were originally created. To follow the latter approach would be to unduly limit the application of Article 31(3)(c), given the broad range of circumstances in which a particular rule may need to be interpreted.
Following from this, if the application of a human rights norm involves the impact of environmental harm on human well-being and the duty of a State to prevent, mitigate, or refrain from causing that harm, and there is an external legal rule which regulates that type of harm, then that rule is likely to be relevant in the interpretation of the human rights norm. 109 This could be applicable in a number of different contexts from marine and river pollution, 110 to hazardous substances and toxic chemicals, 111 to nuclear fallout. 112 Where such hazards cause harm to human life and well-being, there are a number of potentially useful international legal instruments to draw from as interpretive aids.
It is not only rules regulating the same type of environmental harm that could be considered relevant, however. International environmental law also includes numerous legal standards which relate to the processes to be followed in cases of real or potential environmental harm. For example, the 1991 Convention on Environmental Impact Assessment in a Transboundary Context (Espoo Convention) requires State Parties to carry out a number of specific procedures related to environmental impact assessment wherever a project is likely to cause significant transboundary environmental harm. 113 The fact that this only applies to transboundary harm and the limited number of State Parties to this Convention could certainly limit its direct use as an interpretive aid in human rights cases. 114 However, the obligation to carry out an environmental impact assessment is increasingly being recognised as a rule of customary international law. 115 It could thus be used to inform the content of a State's duties to take steps to prevent or to minimise environmental harm so as to fulfil its human rights obligations.
There are also rules within international environmental law which may be understood as creating rights for individuals and groups. The Aarhus Convention establishes three key procedural rights centred around access to environmental information, public participation in decision-making processes relating to potentially harmful activities, and access to justice for environmental matters. 116 The 1992 Convention on Biological Diversity (CBD) can also be read as creating certain rights for indigenous peoples with regard to traditional practices and knowledge, and the use and conservation of related elements of biodiversity. 117 These particular rules could even be understood as relevant following the stricter approach to the relevance criterion, since they are essentially created to regulate the same or similar situations as particular human rights norms.
For example, both Article 27 of the ICCPR and Article 8(j) of the CBD protect indigenous peoples and cultures. 118 Article 27 of the ICCPR has regularly been applied in the context of biodiversity conservation, most often in relation to reindeer herds in Scandinavia. 119 In none of these cases was reference made in the Views to the CBD. It is not clear why this is: perhaps because the parties and the HRC did not deem it relevant, or perhaps because the standard in Article 8(j) is so much lower than the standard required by Article 27 that it would not have helped either way. 120 Arguably, it is more likely that it simply did not occur to the parties that this might be a tool for interpretation which could be called upon. Following the analysis above, however, the CBD could indeed provide an interpretive aid in such cases. Similarly, where human rights cases involve access to environmental information or access to justice (as a number of these Article 27 cases arguably do) 121 the Aarhus Convention could provide relevant rules to aid interpretation. 122
It seems as though some of these points of relevance have already been recognised: in the UN Special Rapporteur's Framework Principles on Human Rights and the Environment, certain aspects stand out to those familiar with international environmental law. 123 The focus on public access to information, public participation in decision-making processes, and access to justice for environmental matters in Principles 7, 9, and 10 reflect the key provisions in the Aarhus Convention, 124 while the call for environmental impact assessment in Principle 8 recalls treaty 125 and customary 126 norms on such assessments. This recognition has not, however, made it beyond pronouncements of the Special Rapporteur into the jurisprudence of the treaty bodies – yet.
We saw above that there has been and likely will continue to be a rather flexible approach to the identity of the parties in regard to the external rule. It seems likely going forward that the primary consideration will be whether the State Party which is the duty-bearer in a particular human rights context is also bound by the external rule in question. Some of the international environmental instruments referred to above have a relatively low number of parties (such as the Espoo Convention with 45 parties or the Aarhus Convention with 47 parties), 127 while some have attained near global ratification (the CBD currently has 196 parties, for example). 128 The use and utility of these instruments will therefore depend on the relevant treaty and the identity of the State Party in a particular human rights case. Where an environmental standard is also reflected in customary international law, such as some of the rules on environmental impact assessment, this will fall under the scope of ‘applicable in the relations between the parties’ provided the State in question is not a persistent objector to that rule. 129
Following from the above analysis, intertemporality is unlikely to be an issue in human rights cases. The open-textured nature of human rights standards and the dynamic approach that has been taken regarding their interpretation means that they may be subject to such evolutive standards. This means that modern environmental standards can be used and human rights standards may change alongside developing environmental standards.
Turning finally to the interpretive impact of environmental standards, international environmental treaties should not be applied directly as a minimum standard, but they may be used to inform the nature and extent of States’ duties in a human rights context. The extent to which international environmental law standards will impact the content of human rights obligations must be determined alongside the application of the other elements of Article 31 and must therefore be weighed together with the ordinary language of the treaty terms in the context of the rule. In essence this means that where the ordinary wording of the treaty itself is very clear, the impact of external legal rules on their interpretation will be minimal. Article 31(3)(c) does not operate to import external legal standards, but rather to help clarify meaning and ensure systemic coherence by reference to relevant international law alongside the general rule of treaty interpretation in Article 31(1) of the VCLT.
Moving beyond the context of the case discussed above, one of the potential uses of Article 31(3)(c) relates to the clarification of particular terms as well as standards of conduct. 130 Certain terms in UN human rights law, such as ‘environmental pollution’ or ‘natural environment’ in the CRC, 131 could find further clarification from international environmental law. ‘Pollution’, for example, is defined in a number of international instruments in relation to different contexts. 132
There is unfortunately still a significant degree of uncertainty as to how UN treaty bodies will deal with these questions. Nonetheless, it has been established in the preceding sections that international environmental law could indeed provide a multitude of tools for the interpretation of human rights in different contexts. Having established this possibility, the following section reflects briefly on the advantages and disadvantages of making use of these tools.
Evaluation
The advantages of using international environmental legal standards as interpretive aids in human rights law are clear. The interaction between human rights and the environment is undeniably and increasingly important and relevant. Environmental harm poses a severe and significant threat to human well-being and even the continued existence of human civilisation. Human rights law presents an important tool for counteracting environmental harm and for holding States to account where they fail to prevent such harm. Integrating environmental legal standards into human rights law can in theory serve to bolster and complement this protection.
There may, however, be limits to the utility of this systemic integration. As discussed above, international environmental standards are often relatively low. This may indeed be part of the reason why we have not seen much use of environmental standards thus far by States. In the best case, they may prove to contribute relatively little to human rights standards, since human rights themselves require much higher standards of conduct by States. In the worst-case scenario, reference to low international environmental legal standards could even serve as to pull down or undermine human rights standards. In the Torres Strait Islanders case, the Paris Agreement was treated by the applicants as a minimum threshold. But what if a State Party were to argue that, since they had complied with all binding environmental standards, this was evidence that they had taken adequate steps to fulfil their human rights obligations? In other words, what if the environmental standard became not the minimum standard, but the sufficient standard of conduct? Although there is little evidence of this thus far, it is a risk that should be taken into consideration.
Reading human rights in light of international environmental standards has also been criticised for undermining environmental protection from an ecocentric perspective and replacing it with an anthropocentric perspective. 133 This stems from a structural criticism of using human rights law to address environmental problems. By its nature, human rights-based litigation is usually human-focused and individualistic, and as such is said to fail to recognise the intrinsic value of the environment 134 or its status as an international public good. 135 It has thus been argued that using environmental standards to interpret human rights could influence the future development of international law, ‘hindering its potential evolution’ towards broader protections for the environment beyond its immediate impact on human well-being. 136
It is outside the scope of this article to discuss the utility of environmental human rights litigation in general, but it is worth responding to this criticism in brief. Even if the legal and enforcement structures of human rights law do indeed limit the potential for their use as environmental protection mechanisms, this does not necessarily imply that using human rights litigation hinders environmental protection through other mechanisms. Human rights litigation is but one tool that should be used alongside others. Shelton reasons that there is no conflict between human and other environmental interests; we are not ‘separable members of the universe’ but ‘interlinked and interdependent participants’ and therefore protection of human environmental interests can only be a positive thing for the environment as a whole. 137 Aside from the broader debate on the utility of human rights litigation as such, it is unclear why the use of environmental standards in the interpretation of human rights would have any of the negative effects that are the subject of such warnings. If the issue or circumstance in question is already being litigated according to human rights law, the integration of concepts and standards from international environmental law simply serves to inform that litigation; if anything, it could serve to counteract the individual focus by integrating standards that have been negotiated with a broader perspective in mind.
Another potential risk with the approach has been taken relates to the problem of normative coherence identified in Section 2.2.2. above. It has been shown that UN human rights bodies tend to take a flexible approach towards the identity of the parties to the external rule – that is, the interpretation of ‘applicable in the relations between the parties’ in Article 31(3)(c).
While this broadens the potential scope of application of systemic integration in this context, it runs the risk that human rights obligations may be interpreted differently in relation to different States. For example, in Portillo Cáceres the HRC was able to make reference to the Stockholm Convention because Paraguay was a party to that treaty. What if the exact same thing happened in Turkmenistan, a State which has not ratified the Stockholm Convention? 138 The Committee would presumably not be able to refer to the Stockholm Convention, and thus could in theory have come to a different conclusion. This is potentially problematic from the perspective of systemic coherence in international law, and with regard to the principle of equality underpins human rights standards. 139
One might argue in response that human rights standards are never perfectly equal in the sense that States choose to ratify particular treaties and not others, and therefore the extent of protection will inevitably differ across different polities. Nonetheless, there is a difference between acknowledging that particular rules may be applicable in particular States, on the one hand, and accepting that the same rule applies differently in different States. In essence, the protection under a particular Article of a particular human rights treaty may be more-or-less stringent dependent upon other treaties that the State may or may not have ratified. The differential interpretation of the same rule thus poses a challenge not only to equality but also to normative coherence, both in human rights law and in international law more broadly.
Finally, a key factor in the overall evaluation of this method of interpretation is the clarity and transparency with which the method is used. It has been noted before that the method of interpretation used by UN human rights bodies is often lacking in transparency. 140 The lack of a clear and transparent method can undermine the legitimacy of the output of such bodies. It can also reduce the overall impact and persuasive force of their conclusions. 141 Thus, the overall benefit of integrating international environmental law into the interpretation of human rights is partially dependent on the extent to which this interpretive process is clear, transparent, and explicit.
Clarity and transparency have unfortunately been noticeably absent in many of the examples discussed above. In the Torres Strait Islanders case, the Committee noted the arguments of the parties in relation to Article 31(3)(c), and even found that ‘the appropriateness of such interpretations relates to the merits of the authors’ claims under the Covenant’, 142 but then never explicitly considered this question of interpretation in its Views on the merits. The Committee did indeed find that there had been a violation of the applicants’ rights under Articles 17 and 27 of the ICCPR, based largely on the failure to take appropriate adaptation measures. 143 It is unclear whether or to what extent Australia's obligations under the Paris Agreement were taken into account. Similarly, of all the examples given above where UN human rights treaty bodies have referred to external legal rules (whether stemming from environmental law or other areas of law), only the CRC, in referencing the Hague Convention 1980, has ever explicitly referred to Article 31(3)(c) of the Vienna Convention when doing so. 144 In the other cases, statements, and General Comments discussed above, it is unclear on what basis the treaty body is referring to other international agreements. 145 The legal basis – whether Article 31(3)(c) VCLT or otherwise – for referencing external legal rules is uncertain.
The advantage of interpreting human rights in light of international environmental rules will only be fully realised if accompanied by clarity of interpretive method. If environmental standards are taken into account implicitly, without reference to their source and/or in the absence of a clear and explicit legal basis for their inclusion in the interpretive process, the final output risks lacking legitimacy and persuasive authority. Transparency is therefore an essential factor in the potential impact of this method.
One important factor to recall in this context is the membership of UN human rights bodies in contrast with the members of the bench in other judicial organs like the ECtHR. Many are ‘independent experts’ or people ‘of high moral standing and recognized competence and experience in the field’ 146 who do not necessarily have any legal background at all, let alone in public international law. 147 This is likely to impact the extent to which they explicitly refer to instruments like the VCLT and their application of such rules as Article 31(3)(c). It may be that for the full potential of systemic integration to be realised, it will require advocates to raise and explain these dynamics of interpretation thoroughly and appropriately in this context.
CONCLUSION
This article explored the integration of international environmental legal standards in interpreting human rights law by UN human rights treaty bodies, focusing on Article 31(3)(c) of the VCLT. It examined how this systemic integration mechanism operates in this specific context.
The analysis led to several key conclusions. First, systemic integration is applicable, allowing UN human rights bodies to consider international environmental law when interpreting States’ human rights obligations. While these bodies may not use this approach as enthusiastically as other human rights courts, it remains a viable method. Second, international environmental rules can serve as interpretive aids if they are (i) relevant to the application of human rights law in a particular case, for example where the case involves a particular type of environmental harm or environmental process rights; and (ii) binding upon the State in question. Third, the impact of external environmental rules on human rights interpretation depends on the specific case and must be balanced with other interpretive elements under Article 31 of the VCLT. While international environmental law should not act as a direct minimum standard for human rights, it can inform their content.
Integrating international environmental standards into the interpretation of human rights offers benefits for both environmental and human rights protections. However, it also poses risks, including potential normative incoherence and inequality among rights-holders in different States. For this integration to be effective, the interpretive method must be explicit and transparent. A lack of clarity in the interpretive process can undermine the legitimacy and authority of human rights bodies’ decisions.
Ultimately, Article 31(3)(c) offers a valuable tool for systemic integration. When used carefully and transparently, it could become a significant part of the UN treaty bodies’ interpretive approach.
Footnotes
Declaration of Conflicting Interests
The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author received no financial support for the research, authorship, and/or publication of this article.
