Sustainable Development: A Principle of EU External Relations Law?

Table of contents: 1. Introduction. – 2. Genesis and place of sustainable development in EU Treaties and policy. –  3. Sustainable development in substantive EU external policies – 3.1. Trade policy. – 3.2. Development cooperation. – 3.3 External environmental policy. –  4. Conclusion.  

Abstract: The contested concept of sustainable development is ubiquitous in EU law, including in EU external relations law. Its legal status as a principle, however, lacks clarity, much like in international law. Sustainable development is prescribed as an aim to be pursued in the EU’s relations with the wider world both under Article 3(5) and 21 TEU. It has acquired particular prominence in the fields of EU external action traditionally associated with this concept, such as trade policy, development cooperation and environmental action, although its application varies across each of these fields.  The use of sustainable development, however, is not confined to these domains only, and it often features in relation to other areas of EU external relations. Within this context, this article questions whether sustainable development could possibly be considered a separate principle of EU external relations law. For this purpose, it traces the position and origins of this concept in the EU constitutional framework. Most importantly, the article analyses the manifestations of this concept in the key fields of external action mentioned above, namely trade policy, development cooperation, and environmental policy. In this connection, it critically examines the relevant case law of the Court of Justice of the EU for any hints on the nature of this concept. Ultimately, the paper argues that sustainable development is not a principle of EU external relations law, but it is inherently linked to other principles, such as coherence and principle of integration. 

Keywords: sustainable development – integration – coherence – trade – development – environment.

1.   Introduction

The concept of sustainable development (SD) has received considerable attention in various fields of law. Introduced in the 1992 Rio Declaration, the vagueness of SD allowed it ‘to rally rather than divide,’ bringing together both developed and developing countries around the international environmental agenda.[1] However, the content of this concept remains unclear beyond the central idea that environmental preservation goes hand in hand with economic growth and social development, a notion that has fuelled much academic debate over the past three decades.[2] Some have criticised it for shifting the focus away from environmental protection and serving as a form of window-dressing that reinforces the existing model of economic growth.[3] Nevertheless, SD has become a fixture of the international agenda, including through the adoption of the UN Sustainable Development Goals (UN SDGs) in 2015 as part of the Agenda 2030 – the most recent framework aimed at guiding national policy.[4] The SDGs have likewise drawn criticism for their incoherence and lack of binding legal force, among other issues.[5] SD influenced not only prominent soft law frameworks, but also key treaty regimes including the climate change regime.[6]

Despite its ubiquitous presence, however, its role in international law remained far from clear. Scholars were skeptical about the status of SD as a fully crystallized principle with binding legal force, often offering divergent views on the very content of SD.[7]Others pinpointed ‘a norm-aspiring’ and ‘an interpretive function’ of SD based on its presence in international law, including international jurisprudence.[8] Although occasionally referred to in international jurisprudence as an interpretative tool, until recently, rarely would an international court refer to it as a principle, as did the international arbitral tribunal in the Iron Rhine case.[9] As for the International Court of Justice’s (ICJ) jurisprudence, the concept remained vague for a long time. In Gabcikovo-Nagymaros, while Judge Weeramantry argued in his dissenting opinion that SD should be recognised as ‘a principle with normative value,’ the majority decision referred to it as a ‘concept’ expressing the ‘need to reconcile economic development with protection of the environment’, arguably informing the outcome of the case.[10] In Pulp Mills, the ICJ referred to SD as an objective using it as an interpretative tool.[11] Only in its recent Advisory Opinion on climate change did the ICJ take a major leap in recognising SD as a principle capable of  ‘guiding’ the interpretation of treaty norms and the determination of customary rules, including such customary law principles such as the no harm principle.[12] It is the ‘continuous and uncontested universal recognition’ of SD that appears to persuade the ICJ to accord SD with such normative content. While early reactions on the ICJ opinion have been focusing on its significance for the climate change regime,[13] it is clear that the Court’s pronouncement on SD deserves further attention even though it falls outside of the scope of this article. The position of SD in international law was briefly sketched here in order to draw a parallel with similar debates on the status of SD in the domain of EU law. 

Despite the absence of a clear definition in Treaties or case law, SD is equally omnipresent in EU law. In EU environmental law scholarship, SD is occasionally referred to as a ‘principle’ of EU law among others due to the repeated statements to SD including in the field of EU external relations, though its legal significance and enforceability remain questionable given its vague and indeterminate nature.[14] More commonly, however, scholars view the latter as an aim to guide policy – a ‘lifestyle a society should aim at’ –, rather than an enforceable legal norm,[15] more akin to a legal principle. Although the term ‘principle’ remains contested in international, European and national law,[16] it is generally distinguished from mere objectives. A principle is associated with legal effect: it is a legal norm of ‘a more fundamental character’ from which rules derive and with which they must align.[17]Principles ‘incorporate a minimum substantive content and guide the judicial inquiry on that basis’, setting limits and steering legal outcomes.[18] Principles should thus be distinguished from mere objectives as a matter of more authoritative, normative force. 

So, to what extent can SD be regarded as a principle of EU external relations law? The concept has gained particular prominence in areas of EU external relations traditionally associated with the concept, such as trade policy, development cooperation, and environmental action. At the same time, SD resonates more broadly and has been a recurring theme in foreign policy documents since the late 1990s. It is therefore unsurprising, that in his influential conceptualisation of the EU as a ‘normative’ actor, Manners classified SD as a ‘minor norm’, which he suggests can be contested.[19]  More than two decades have passed since then, and SD has gained even greater significance within the EU’s constitutional framework and external relations, regularly appearing in policy and legal instruments. Kassoti and Ott, however, warned against overestimating the influence of SD in EU external relations law, particularly in light of the ‘growing discrepancy between EU rhetoric on [SD] and the reality on the ground of practice’.[20] Bearing in mind this warning, to which extent can the prominent use of SD in EU external relations law translate to a normative depth associated with a principle as described above? In terms of its content, would it mandate a balance to be struck between the economic growth and other pillars of the concept as suggested by the arbitral tribunal in the Iron Rhine case? And if so, is there a balance – seen as the ‘essence’ of SD – to be struck in practice in EU external relations law?[21]

To address this question, the article first traces the origins of SD within the EU’s constitutional and policy landscape, particularly in relation to external relations. The analysis then turns to the expression of SD in key areas of EU external action – trade, development cooperation, and environmental policy. The article ultimately argues that, while SD does not constitute an autonomous principle of EU external relations law, it is closely linked to other foundational EU law principles, notably the principles of coherence and integration.

2.   Genesis and place of sustainable development in EU Treaties and policy

A contemporary of the Rio Declaration, the first allusion to SD appeared in the Maastricht Treaty. This was seen as paying homage to the Brundtland Report, coupling economic development with environmental protection.[22] Without referring to SD directly, the Maastricht Treaty included ‘promotion, throughout the Community, of a harmonious and balanced development of economic activities, sustainable and non-inflationary growth respecting the environment’ among the objectives of the European Communities (EC).[23] In addition, the Maastricht Treaty reformed the legal basis for development cooperation including sustainable economic and social development of developing countries among its objectives.[24]

The direct reference to SD appears for the first time in the Amsterdam Treaty. While the preamble referred to SD as a ‘principle’, the latter appeared among the revised objectives of the EC.[25] Suggesting an early lack of clarity regarding this concept,[26] this development also mandated a policy of economic growth, social development and environmental protection.[27] The Amsterdam Treaty, moreover, introduced the linkage between environmental protection and SD. The revised clause on environmental integration – present in the Treaty since the Single European Act (SEA) – highlighted that taking into account of environmental concerns should take place ‘in particular with a view to promoting [SD]’, a formulation currently found in Article 11 TFEU discussed below.[28]

SD began to feature in EU policy documents as a goal ‘to be achieved’, with development cooperation and trade highlighted as priority areas.[29] The Commission’s 2001 Communication on SD Strategy described SD as a ‘positive long-term vision’.[30]Although largely inward-looking, the Strategy focused on the EU ‘putting its own house in order’ to show global leadership.[31]Without adopting the text of the Communication, the Gothenburg European Council endorsed a broad and vague strategy, emphasising the need for a global dimension and framing SD as a ‘fundamental objective under the Treaties’.[32] Importantly, the 2001 SD Strategy was seen as ‘one of the key frameworks’ for policy coherence.[33] Its global dimension was further developed in the Commission’s 2002 Communication on a Global Partnership for SD, which aimed to set out the EU’s ‘contribution to global [SD]’ highlighting the role of coherence.[34] It also defined development which is sustainable, namely development which ‘must strike a balance between the economic, social and environmental objectives of society, in order to maximise well-being in the present, without compromising the ability of future generations to meet their needs’.[35]

Subsequent policy papers began to reflect a broader interpretation of what constituted SD. The 2005 European Council Principles of SD to guide policy and decision-making referred to the latter as a ‘key principle of all [EU] policies and action’ even though it is clear from the rest of the document that SD is an overarching objective, the achievement of which hinges upon coherence and principle of integration more broadly.[36] It is in the same document that we see the early signs of ‘inflationary use’ of SD,[37]where SD goes beyond the three associated pillars to include human rights, public participation, democracy and other issues. The same broad approach translated into the 2006 Revised SD Strategy, where a wide spectrum of EU external policies, including the Common Foreign and Security Policy should contribute to its achievement.[38] Here, the Council sets out ‘policy guiding principles’ to achieve SD, which include a broad range of principles pertaining to environmental governance, good governance, but also policy coherence and integration more broadly.[39]

The Lisbon Treaty further elevated the prominence of SD within the EU’s legal framework. It is not so much the TEU preambular reference to SD as a principle that signals its prominence,[40] but rather the transformation of SD as an ‘overriding objective’ of the EU in Article 3(3).[41] Although there is a view that Article 3(3) TEU grants equal recognition to all three pillars of SD unlike the Amsterdam Treaty,[42] others contend that the emphasis remains predominantly on economic growth. [43] Article 3(5) TEU in its turn for the first time directly linked SD and EU external relations law more generally, calling for EU contribution to SD of the Earth among its other objectives.[44] This is viewed as one of the key achievements of the Lisbon Treaty alongside Article 21 TEU,[45] which includes in its paragraph 2 the objectives to: 

‘(d) foster the sustainable economic, social and environmental development of developing countries, with the primary aim of eradicating poverty; […]

(f) help develop international measures to preserve and improve the quality of the environment and the sustainable management of global natural resources, in order to ensure [SD] […]’.

While the language of these objectives is closely tied to development cooperation and environmental policy, they extend beyond these areas to apply across all fields of EU external action. This ‘elevation’ of SD from a development-specific goal to a broader objective is seen as a way to strengthen the coherence of EU policies, [46] particularly in light of Article 21(3) TEU, which mandates consistency across all external action. Article 21(1) TEU also refers to the principles guiding EU external action, which reflect the values in Article 2 TEU – though, notably, SD is not explicitly listed among them.[47]

Alongside these provisions, Article 11 TFEU is viewed as being at the core of SD in EU law, labelled as ‘[t]he main provision’[48] on SD or a provision ‘codifying’[49] SD in the Treaties. The relationship between these provisions, however, is unclear. It must be noted here that the integration of environmental concerns is viewed as one of the components of SD in IEL,[50]perhaps ‘the only one which might be understood as having legal consequences’.[51] In this sense, the principle of integration in Article 11 TFEU while reinforcing the environmental pillar of SD,[52] does not require prioritisation of environmental concerns. It rather  sets an obligation to integrate environmental protection requirements into other policy areas as a legal obligation.[53]Moreover, the legal force of Article 11 and its ability to serve as a ground for a judicial challenge for a failure to take environmental protection requirements into account is doubted.[54] Besides, the language of Article 11, specifically the reference to ‘with a view to promoting SD’, does not support the reading that it constitutes the core of SD: rather, it implies that SD is ‘a broader objective that cannot be achieved through environmental integration alone’.[55]

Some argue that Article 11 TFEU stems from references to SD in Articles 3(5) and 21 TEU.[56] However, these references came later, [57] while the foundation for environmental integration was laid earlier in the SEA, where Article 130r(2) EC required environmental protection to be part of all Union policies, including external ones.[58] What more clearly links these provisions is the principle of coherence. Article 11 is seen as embodying this principle in relation to environmental policy, with similar requirements present also in the Common Commercial Policy (CCP) and development cooperation.[59] With Articles 3(5) and 21 TEU, coherence has been further strengthened,[60] firmly linking SD to both environmental integration and coherence in EU external relations.

At the same time, Article 11 is not the only ‘integration’ clause relevant to SD; Article 9 TFEU should also be considered. The elevation of other integration clauses in the Lisbon Treaty, however, may signal a ‘dilution’ of the specific obligation in Article 11 regarding environmental protection.[61] Still, Article 11 uses stronger language than other clauses, and its relevance is reinforced by SD’s status as an overarching objective in Articles 3(5), 21(2) TEU, and Article 37 of the Charter. [62] Article 37 of the Charter mandates that ‘a high level of environmental protection and the improvement of the quality of the environment must be integrated into the policies of the Union and ensured in accordance with the principle of [SD]’.[63] This reference to the ‘principle of SD’, on its own, however, does not signal an elevation of SD to the status of a principle, given Article 37’s limited legal weight.[64] Rather, it is generally viewed as a reflection of the principle of environmental integration.[65] In a case concerning the Birds Directive, the CJEU referred to the combined framework ‘provided for both in Article 3 TEU and in Article 37 of the Charter, provisions according to which, in essence, the [EU] is to work for [SD] and ensure a high level of protection of the environment.’[66] Notably, the Court gave no interpretive weight to the mention of SD as a ‘principle’ in Article 37.

Overall, the combination of the provisions discussed above suggests that SD, within the primary legal framework, stands as a clear overarching objective of EU external action, integrating the aims of various foreign policy areas. Voight notes this complex pursuit of objectives within the ‘cross-cutting and horizontal objective’ of SD, which in its turn has to be balanced against numerous other EU objectives set out in Article 21 TEU, in addition to Article 3(5) TEU.[67] As for the status of these objectives, including those referring to SD, it is hardly possible to rely on any specific objective to invalidate a particular external action: the objectives are simply too general and lack prioritisation.[68]

What is then the legal value of SD as an objective as opposed to a principle? The references to SD in Articles 3(5) and 21 TEU – alongside Article 11 TFEU –  oblige the EU to ‘continuously pursue’ it as an objective.[69] Besides, as an objective it has a certain legal value and ‘normative dimension’ where the relevant law should be interpreted in the relevant light.[70] At the same time, none of these provisions ‘mandates a balance’ between the three pillars of SD,[71] or  indicates the manner in which SD must be pursued which might elevate it to a principle. In the same vein, post-Lisbon policy papers repeatedly emphasise SD as a fundamental and overarching objective of the EU that should be mainstreamed in EU policies.[72] The EU action for SD is to contribute to the UN SDGs, through a range of policies including trade, development cooperation, humanitarian assistance, prevention management and resolution of crises without mentioning environmental action separately.[73] Thus, rather than seeking to strike a balance between the three pillars, SD is to be achieved through a range of policies where coherence plays a crucial role.[74]

The EU’s constitutional and policy frameworks thus clearly treat SD as an overarching objective, albeit linked to the principle of coherence and environmental integration. What about the concrete expressions of SD in substantive EU policies? The article turns to this question next. 

3.   Sustainable development in substantive EU external policies  

To trace the manifestations of SD in the areas associated with the three pillars of SD, it is necessary to question the relevant policy framework, key instruments, as well as available case law in each policy field. 

3.1.  Trade policy

SD started featuring in EU trade policy documents few years after the Rio Summit as an objective of the EU linking trade and environment.[75] It also featured within trade agreements concluded in the years following the adoption of the Maastricht Treaty, for instance, in the Partnership and Cooperation Agreements, entry-level trade agreements concluded with a number of post-Soviet countries.[76] The concept has acquired particular prominence in the subsequent decade, when the Council mandated trade policy to be used to improve the environmental and social standards in bilateral relations in the context of the 2006 SD Strategy.[77]Specifically, new trade agreements were to include environmental protection and social standards from now on thus already before the Lisbon Treaty reform and the introduction of Article 21 TEU.[78]

Trade and SD chapters (TSD) have since become a fixture of new generation trade agreements – ‘post-Global-Europe Agreements’,[79] contributing to the pursuit of SD as an objective within the broader IEL framework.[80] A survey of trade agreements concluded since 2010 reveals an interesting picture in relation to SD. The majority of the agreements refer to SD directly as an objective in the preamble, the general objectives of the agreement or specific articles under the TSD chapters (or related provisions).[81] The preambles of Association Agreements concluded with Ukraine, Moldova and Georgia refer on the other hand to ‘principles’ of SD. While in the case of Ukraine, the reference is to ‘principles of [SD] and green economy’, its Georgian and Moldovan counterpart include only ‘principles of SD’.[82] First of all, it is quite obscure what such ‘principles’ would entail. Second, the substantive provisions in the Ukrainian Agreement clarify that SD is a common objective to be pursued by the agreement, including its TSD chapter.[83]  Meanwhile, in the case of Moldova and Georgia the agreements include a provision reaffirming the parties’ commitment to the ‘principles of free market economy, [SD] and effective multilateralism’ alongside provisions treating SD as an objective.[84] There is thus a significant inconsistency in this group of agreements in terms of terminology used, but the references to the ‘principle’ or ‘principles’ of SD alongside other concepts, such as green economy and multilateralism indicates that this is merely rhetoric, rather than a concrete legal principle. 

The most peculiar in this respect is the trade agreement concluded with Central America which declares in its Article 1 that:

‘The Parties confirm their commitment to the promotion of [SD], which is a guiding principle for the implementation of this Agreement, taking notably into account the Millennium Development Goals. The Parties shall ensure that an appropriate balance is struck between the economic, social and environmental components of [SD].’[85]

This reference to the requirement to strike an ‘appropriate balance’ between the three pillars of SD is remarkable due to the articulation of what would be expected of the principle of SD. At the same time, the preamble and other provisions of the agreement make it clear that SD is an objective to be achieved.[86] Crucially, the obligations concerning the social and environmental dimensions do not indicate that a genuine balance with economic development is being pursued, mirroring the approach found in the TSD chapters of other agreements. 

The substantive provisions on environmental and social standards in TSD chapters differ most prominently from the trade-related obligations not only in terms of their scope, but also in terms of the nature of legal obligations. Most importantly, the weak formulations contained in many provisions in the earlier agreements raised questions about their meaning and doubts about their legal weight.[87] The obligations in the TSD chapters have been labelled as ‘not fully enforceable’,[88] with many compliance issues raised.[89] It should be noted that the TSD obligations significantly evolved and expanded over the last few years both in relation to environmental and social standards to include at times detailed obligations, as well as new issues – gender equality, for instance.[90] A standard TSD chapter currently includes a general section on TSD, along with specific sections on trade and the environment, and trade and labour. These may appear as a single chapter[91] or as three consecutive chapters, with the TSD chapter providing the overarching framework for the other two.[92] The TSD chapters have also evolved to reflect major international developments, for instance post-Paris Agreement TSD chapters include related obligations concerning climate change.[93] Despite this evolution, however, an argument has been made regarding environmental protection that rather than seeking to balance trade objectives versus environmental protection, environmental protection is integrated in a very specific form, the bottom line being creating an environmental level playing field.[94] This criticism would equally apply to the social standards set in TSDs. There is thus no ‘balance’ in terms of the nature of obligations pertaining to the three pillars of SD. For this reason, scholars have argued for including SD-related obligations beyond the TSD chapters rather than expanding less enforceable TSD chapters.[95]

In this context, Opinion 2/15 is particularly relevant. Both the Advocate General (AG) and the Court clearly viewed SD as an objective while undertaking a competence delimitation even though neither strictly speaking applied the centre of gravity test. [96]AG Sharpston considered Article 21 TEU irrelevant and treated SD as a separate objective, concluding that environmental and social aspects are not integral to the CCP.[97] In contrast, the CJEU found that that SD issues are indeed an integral part of the CCP, relying on Article 9 and 11 TFEU in addition to Article 21 TEU. The Court’s position underscores SD as a global objective: when combined with the integration principles in Articles 9 and 11, it has helped mainstream social norms and environmental protection in trade agreements. Notably, the Court also clarified that the TSD chapter does not as such regulate social standards and environmental protection,[98] but rather holds parties to their international commitments, suggesting the absence of a balancing mechanism that a principle of SD might require. 

The absence of a principle of SD is reflected also in the existence of a separate dispute settlement mechanism, which emphasises cooperation and reconciliation over enforcement. First of all, this means asymmetrical – different – consequences for a breach of respective trade, environmental and social standards. Secondly, the trade cooperation can proceed while parties are in breach of their obligations under the TSD chapters.  The TSD dispute settlement mechanism was activated only in the case of labour rights violations in South Korea. The EU’s position in the proceedings of the panel of experts and its subsequent outcome was viewed as a rather soft approach and a missed opportunity for the EU to exercise assertiveness.[99] Returning in this context to Opinion 2/15, it is notable that the CJEU established that the EU is entitled to suspend or terminate its commitments under the FTA in case of a breach of the environmental or labour protection-related provisions.[100] On the one hand, this could be potentially seen as strengthening the SD dimension of the trade agreements in response to past criticism.[101] On the other hand this finding is problematic from the perspective of international law.[102] The Court found that the EU could terminate the agreement for violations of TSD obligations on the basis of customary international law, rather than the agreement itself.[103] It relied on the default rule on material breach of the agreement stipulated in the 1969 Vienna Convention although the latter applies to states only, and despite the fact that the default position can be set aside by a specialised rule in the agreement.[104] The TSD dispute settlement procedure would thus apply in case of a breach of TSD provisions unlike the trade-related provisions which might lead to a suspension of the agreement. The different dispute resolution procedures thus also add to the perception of a lack of a ‘balance’ between trade and the environmental and social pillars included in the agreement. Besides, more broadly, even a negative impact generated by the trade cooperation on labour rights or the environment does not mean that trade relations would be discontinued.[105] Trade is therefore prioritised and clearly given more weight than the environmental and social pillars which implies that the concept of SD does not mandate a balance to be struck between the economic growth generated by the agreement and the other pillars as would be expected of the principle of SD.

In connection with the criticism regarding the implementation of TSD chapters, including from EU institutions,[106] the Commission identified non-compliance as an issue demanding further attention in its policy papers since 2015,[107] introducing a ‘15-point Action Plan’ to enhance the implementation and enforcement of the TSDs in 2018.[108] Perceived as insufficient, the position was further revised in the Commission’s 2022 Communication, which aimed to enhance the effectiveness of TSD chapters in promoting SD.[109] It emphasised that ‘TSD commitments are legally binding and enforceable’ introducing the possibility of resorting to trade sanctions as the last resort.[110] The Commission thus proposed the application of the general dispute resolution mechanism allowing for trade sanctions to be extended to TSD chapters in future trade agreements. Such an option, however, is singled out for very specific instances rather than TSD obligations more generally. These include the ‘failure to comply with obligations that materially defeats the object and purpose of the Paris Agreement on Climate Change or in serious instances of non-compliance with the ILO fundamental principles and rights at work’.[111] This new approach has been incorporated in the FTA with New Zealand which entered into force in 2024.[112] The likelihood of restoring to sanctions for breaching the obligations in the TSD chapter, however, has been doubted by scholars given the many challenges associated with it.[113] Ultimately, this brief analysis of TSD chapters and their implementation supports Bartels’ observation that ‘the principle of sustainable development has never been treated as a concrete obligation in itself: none of the agreements admit the possibility of violating the “principle of sustainable development’.[114]

Another instrument, closely associated with the TDSs is the sustainability impact assessment (SIA) instituted alongside the latter serving as a mainstreaming tool in a way.[115] This prior assessment fosters an ‘informed and participatory approach to balancing non-economic interests in trade negotiations’ which comes down to integrating environmental and social concerns during the negotiations.[116] In the 2006 SIA  Handbook, the Commission mentions SD as ‘a principle enshrined in the EU treaties’ while referring to Articles 3 TEU and 11 TFEU,[117] which as discussed above do not provide a sufficient basis for viewing SD as a principle. The legal weight of the SIAs has been linked  to environmental law principles of integration and prevention.[118] As far as any possible balancing between the three pillars of the SD is concerned, the European Economic and Social Committee in its 2011 assessment of the SIAs concluded that economic considerations tended to outweigh environmental and social concerns, and recommended various measures to strengthen the latter two dimensions.[119] Besides, the outcome of the SIAs is also not sufficiently incorporated in the negotiations of the trade agreements.[120] In its 2022 Communication, the Commission emphasises that SIAs should evaluate all relevant trade agreement chapters to identify both the impacts on sustainability and opportunities to further the TSD objectives beyond the dedicated TSD chapter.[121] One can argue that ‘mainstreaming’ TSD objectives in this respect is clearly linked to the principles of integration in Articles 9 and 11 TFEU, rather than requiring any balance to be struck between trade obligations and other environmental protection and social development. Even here, the priority is on trade where the ‘mainstreaming’ could include prioritising the liberalisation of environmental goods and services. In this connection, a recent study demonstrated that the practice of conducting SIAs faces many challenges in responding to sustainability-related issues, as well problems with the involvement of the relevant stakeholders in the process.[122] Thus, while the SIAs certainly aim to integrate environmental and social concerns into the practice of negotiating trade agreements, their design or practice hardly demonstrate that a balance must be struck with trade objectives. 

Ultimately, one must agree with Marín Durán’s observation that the presence of environmental concerns, and by analogy social concerns, within the trade policy instruments is a matter of  ‘political appreciation and choice’.[123] Instead of a balancing act between the three objectives of the SD, these instruments, while indicative of the application of the principle of integration enshrined in Articles 9 and 11 TFEU and striving for coherence, nonetheless prioritise trade.[124] Although, one might argue that this position reflects broader limits on promoting non-trade-related values in international trade law, further inquiry into the concept of SD in development cooperation and external environmental policy similarly reveals it to be a vague notion, whose normative content ultimately reduces to the familiar principles of integration and coherence.

3.2.  Development Cooperation

SD became part of EU development cooperation even before the Maastricht Treaty, which introduced the relevant legal basis listing ‘the sustainable economic and social development of developing countries’ as an objective, seemingly omitting the environmental dimension.[125] The latter, however, featured earlier in 1989 Lome IV convention which mandated that ‘development shall be based on a sustainable balance between its economic objectives, the rational management of the environment and the enhancement of natural and human resources.’[126] In addition, Article 6 of Regulation 443/92 on development assistance to countries in Asia and Latin America included the environment and natural resources as one of the headings for assistance.[127]

Post-Maastricht SD became a fixture of development cooperation, although not all appearances of SD in development cooperation agreements had such a strong wording as in Lome IV. For instance, in EU-India 1998 Partnership Agreement, SD is clearly articulated as an objective in relation to ‘economic development and social progress’, later adding that the cooperation will take place with respect to the environment.[128] In the Cotonou Agreement signed in 2000 the repeated references to SD indicate its status as an objective with a ‘clear-cut emphasis’ on poverty reduction and eventually its eradication.[129] The environment, alongside gender, meanwhile became a ‘thematic and cross-cutting issue’ that was ‘supposed to be taken into account systematically in all areas, levels and phases of ACP-EC development cooperation’,[130] as a clear manifestation of the principle of integration. The significance of the principle of environmental integration was also directly confirmed in Regulation 2493/2000 providing a rare definition of SD.[131] Other policy documents from the same period demonstrate lack of consistency in terms of articulating SD, where at times it is to be promoted and contributed to alongside occasional references to it as a ‘value’ or ‘concept’.[132] The subsequent Economic Partnership Agreements concluded on a regional basis within the Cotonou framework are also indicative of the status of SD as an overarching objective informing the entire agreements.[133] Asymmetrical in nature, these agreements aim at the sustainable economic and social development of ACP countries stimulating their gradual integration into the world-economy compatible with the WTO regime, including in relation to dispute-settlement. They have been, however, criticised for prioritising trade liberalisation at the expense of development element,[134] as well as for undermining regional integration within Africa.[135]

In addition to the lack of a balancing core to the concept of SD, the Cotonou framework also displayed the signs of ‘inflation’ of SD linking it to peace and security.[136] The same approach transpired subsequently in the 2006 European Consensus on Development, as well as the 2011 Agenda for Change: the main objective of poverty reduction should be pursued within the wider context of SD which includes good governance, human rights and political, economic, social and environmental dimensions.[137]The European Consensus was, hence, seen as making a strong nexus with security.[138]A similar broad approach was incorporated in development cooperation funding instruments.[139]

While such a broad framing of SD raises doubts as to its status as a distinct legal principle, it is another legal principle that takes centre stage in this context – namely, the principle of coherence, another Pandora’s box in EU external relations law generating decades of scholarly debate.[140] While the broader discussion about coherence falls outside of the scope of this article, as a cornerstone of development cooperation specifically, it requires the Union to take into account the objectives of development cooperation in the formulation and implementation of other EU policies likely to affect developing countries, including those related to trade, environment, and other fields. The linkage between coherence and SD was already present in the 2005 Communication for Policy Coherence for Development, where contribution to the UN Millenium Development Goals (MDGs), seen as the target framework to achieve SD, encompassed a range of policy fields across which coherence with development cooperation objectives should be pursued, including security, agriculture, energy and many others.[141]

This broad view of what constitutes SD transpired also in CJEU case law. As proclaimed in Philippines Border Mission case, ‘there can be no [SD] and eradication of poverty without peace and security’.[142] This is not surprising in light of the weight given by the Court to the 2006 Consensus on Democracy, which as mentioned above inflates SD. It seems that that the CJEU reads the SD objective as to include the objective of promoting democracy and human rights.[143] The ECOWAS judgement affirms this reading of SD development the relevance of which extends beyond the three pillars associated with the concept demonstrating the nexus with security issues.[144] In an important pronouncement on pre-Lisbon Article 47 TEU, the Court invalidated a Council decision for improperly relying on a CFSP legal basing while pursuing objectives that fall within development cooperation competence. The judgement demonstrated thus that the goals associated with the social and environmental pillars are the ‘minimum’, and the concept itself can have a ‘broader content [which] is malleable and context-specific’.[145]

Similar broad reading of SD is maintained in the Philippines Framework Agreement judgement.[146] In line with its earlier case law, the judgement confirmed that environmental protection is an integral part of the development cooperation, and was seen as potentially reinforcing the requirement of coherence.[147] Based on the Consensus, Development Cooperation Instrument and MDGs, SD is clearly viewed by the Court as the broader objective to be pursued in areas beyond the three familiar pillars to include areas such as migration and agriculture – the latter contributing to poverty reduction.[148] The judgement thus reinforces the importance of Article 11 TFEU principle of environmental integration and coherence.

Subsequently, the reform of the relevant legal basis in the Lisbon Treaty removed the reference to SD: instead, the primary objective of poverty reduction should be pursued within the wider framework of Article 21 TEU objectives. This Lisbon-mandated stronger and more specific focus on poverty reduction and eradication in Article 208 TFEU suggests that development measures must pursue predominantly a goal of poverty reduction. A measure aimed at environmental protection in a developing country would thus not fall under development cooperation unless it also contributes to poverty reduction.[149] This is relevant not only in terms of delimiting competences but also in terms of any perceived balancing exercise that a principle of SD would have demanded. 

The subsequent 2017 Consensus on Development aimed at the achievement of the UN SDGs is infused with the rhetoric of SD, clearly as an ideal to work toward stretching to many issues beyond the three pillars, which must be ‘implemented as a whole and not selectively’.[150] Echoing criticism of the UN SDGs for their lack of prioritisation, this approach involves deploying a broad range of EU policies in the hope that they all contribute to a common goal – the ‘mission impossible’ of achieving coherence in development cooperation.[151] This quest for coherence was repeated in the Commission’s 2019 Communication on policy coherence for development linked to the achievement of the UN SDGs.[152] Furthermore, in the Samoa Agreement (replacing the Cotonou framework with ACP countries) the pervasive invocation of SD – both as a general objective and in relation to specific issues – suggests that it functions more as a rhetorical banner than as a concrete legal principle.[153]

This finding is also be supported by a brief inquiry into the EU’s Generalised Scheme of Preferences (GSP). Although based on a trade legal basis, this instrument is widely seen as a development cooperation tool due to its close affiliation with the objective of social development. In 2002, the Commission indicated that the scheme, one of the oldest of its kind, requires a revision in order to contribute to the achievement of SD.[154] The revision led to the introduction of the GSP+ scheme – the special incentive arrangement for SD and good governance – viewed as a key trade policy instrument integrating environmental and social development concerns.[155] The Preamble of the 2008 GSP Regulation establishing the GSP+ refers to the promotion of SD in developing countries as one of the objectives of the EU’s development policy, and states that the CCP must be consistent with and consolidate those objectives.[156] Alongside trade agreements, the GSP+ incentivises vulnerable low- and lower-middle income countries to ratify multilateral environmental and human rights treaties. 

There are, however, a number of reasons why the GSP+ still prioritises trade and does not pay due attention to other dimensions of SD, including at the stage of implementation. Fist of all, the GSP+ has been criticised in terms of the scope of the conventions it covers, for instance the glaring omissions concerning the international climate change regime.[157] The planned GSP+ revision, providing an opportunity to update the list to include inter alia the Paris Agreement, as well as to improve the monitoring of the scheme, has been delayed. Instead, the existing scheme was extended for the period of 2024-2027.[158] Furthermore, although a 2010 evaluation found that the GSP+ is effective in promoting the ratification of MEAs,[159] the Commission’s primary focus on formal criteria of ratification and the adoption of relevant legislation domestically has been seen as a major shortcoming of the monitoring process.[160] Besides, the EU has rarely suspended benefits due to non-compliance despite documented human rights violations in some beneficiary countries, suggesting a reluctance to jeopardise trade relationships.[161] The weak monitoring and enforcement process therefore suggests a lesser importance for environmental and social standards preferring not to disrupt trade arrangements. 

In sum, similar to trade policy, SD functions as an ideal within development cooperation policy and instruments, albeit more expressly linked to the principle of coherence. 

3.3   External environmental policy

The main policy-setting document in the field of EU environmental action is the Environmental Action Programme (EAP) adopted since 1973. While in the first two decades SD was not part of the discourse yet, the integration of environmental concerns was apparent in the Third EAP adopted for the period of 1982-1986.[162] The Fifth EAP (1993-2000) was adopted in response to the Rio Declaration, which explains its title ‘Towards Sustainability’.[163] The programme was thus geared towards the achievement of SD as a goal, but it had no description of the concept.[164]

The Sixth EAP (2002-2012) was heavy on the rhetoric of SD, mentioning SD or sustainable no less than 64 times.[165] At the same time, it was clear that the focus of the programme is back on the integration of environmental concerns.[166] The Sixth EAP is particularly concerned with the relationship between the programme and the SD Strategy. It makes clear in its Article 2(1) that the EAP should be the basis of the environmental dimension of the SD Strategy with an emphasis on the principle of integration.[167]

The numerous references to SD in the preamble and the text of the Seventh EAP stress SD’s as a goal to be achieved; or it provides the broader context for achieving the priorities for environmental action.[168] The 8th EAP, building on the European Green Deal (EGD), mentions SD in its preamble as something to strive for focusing on environmental integration. The EGD Communication in its turn, when setting out the global dimension of the Deal includes a fleeting reference to SD with a call for a stronger ‘green deal diplomacy’ focused on convincing and supporting others to take on their share of promoting more [SD]’.[169] It should also be mentioned that both the Seventh and Eighth EAPs set out the principles on which they are based: these are the principles of environmental law set in Article 191 TEU, which do not include SD.[170]

As far as specific instruments of external environmental policy are concerned, a significant bulk of EU external environmental policy relates to the EU’s role in participating in multilateral environmental agreements, as well as playing a key role in developing the international treaty regime. The analysis of this aspect of the EU external environmental policy is superfluous for this research. Other key instruments of EU external environmental policy have been already discussed within the framework of trade and development cooperation. There is however another environmental instrument – strictly speaking also a trade instrument, that has not been mentioned so far. This is the bilateral voluntary partnership agreement (VPA) based on 2005 FLEGT Regulation establishing a licensing scheme for timber imported in the EU.[171] Reinforced by the 2010 Timber Due Diligence Regulation, third countries are incentivised to conclude VPAs with the EU ‘providing a presumption of compliance’ with EU law of timber exported from the partner country.[172]

As far as the status of SD development is concerned, two VPAs concluded in the years following the UN Agenda 2030 are noteworthy. The VPAs with Viet Nam and Guyana respectively reaffirm in the preambles the importance attached to the UN 2030 Agenda and ‘in particular the commitment to achieve [SD] in its three dimensions – economic, social and environmental – in a balanced and integrated manner.’[173] The reference to the ‘balanced’ achievement of SD in its three dimensions, however, hardly carries legal weight in this respect. First of all, this is due to it its location in the preamble. Second, the direct link to the UN SDGs raises another questions mark given the breadth of the set objectives. Besides, other VPs adopted in the same timeframe make no reference to the ‘balanced’ achievement of SD, instead highlighting specific UN SDGs in the relevant passage. 

In summary, the key policy documents on external environmental policy, along with instruments such as the VPAs confirm the hitherto observed role of SD as a general goal to achieve also in this field of EU external relations. 

4.   Conclusion

It is clear that SD has become a fixture of EU legal and policy framework relevant for its external relations. Reflecting the international prominence of the concept at the time, the roots of SD in the EU Treaties are firmly placed in the reformulated EU general objectives, as well as the specific objectives of EU development cooperation. The shifting appearances of SD in EU treaties over successive constitutional amendments revealed its connection with the principle of environmental integration, as well as the principles of coherence, receiving a certain normative impact. The latter has acquired a particular prominence in light of Article 21(2) TEU elevating SD to a cross-policy external objective of the EU. The occasional preambular references to SD as a principle has remained just that. When the CJEU encountered the concept in its case law on EU external policies, it treated is as an objective in its inflated understanding reflecting the relevant policy framework on SD. The latter is thus an objective, the achievement of which requires action in many fields of EU external relations, including security, migration, democracy and human rights. Neither does the analysis of the relevant instruments in the areas associated with the pillars of SD indicate that there is a normative core to SD as a principle. The occasional references to balancing of the three pillars or the need to do so are odd-ones out and on closer inspection come down to the principle of integration or coherence. 

Although trade instruments have significantly evolved to recognise the importance of environmental and social concerns, they still prioritise trade, even in instruments closely linked to SD. None of the relevant trade instruments analysed in this article demonstrates that a balance is being struck with the other two pillars of SD; instead, they reflect the application of the principle of integration under Articles 9 and 11 TFEU and a broader quest for coherence. As for the role of SD within development cooperation, although deeply embedded within the latter, SD functions primarily as a broad policy objective rather than a distinct legal principle. Its implementation relies on and is shaped by the principle of coherence, which ensures that development goals are integrated across various EU policies, including trade, environment, and security. The evolving and often expansive use of SD – particularly in legal texts, policy instruments, and CJEU case law – demonstrates its rhetorical and consolidative role, but not the normative clarity or balancing function required of an autonomous legal principle. In addition, the policy framework and the instruments of EU environmental action clearly treat SD as a goal and a broader context within which environmental action should be taken with an emphasis on the principle of integration in Article 11 TFEU. Indeed, even those who regard SD as a principle with a ‘constitutional dimension’ ultimately reduce it to the principle of integration and its role as a foreign policy objective.[174]

To sum up, SD does not constitute a separate principle of EU external relations law, but rather a cross-policy objective guiding action not only in the three fields associated with SD, but also beyond. Its pursuit however is dependent on the application of other principles of EU external relations law, including the principle of coherence and principles of integration as set out in Articles 9 and 11 TFEU. Ultimately, as long as there is no ‘strong’ understanding of SD in EU law, where environmental considerations are prioritised over the others,[175] it is best if SD remains a goal to aspire to rather than a principle mandating a balance which might come at the expense of the environment.