Grecsy Gabriela Llatance Oyarce

Estudiante de Derecho en la Pontificia Universidad Católica del Perú

Historically, jus post bellum was introduced as the third component of just war theory. Immanuel Kant, in the modern age, identified the triptych and proceeded to divide the three categories, Right to War (Recht zum Krieg), Right in War (Recht im Krieg), and Right after War (Recht nach dem Krieg), associating this third branch with some principles of justice, such as fairness of peace agreement, in which included the prohibition of treaties that could lead to future conflicts (Stahn, 2007, p. 314).

The idea of a tripartite conception was displayed for scholars from different traditions of thought, who explained its connection to Jus Ad Bellum and Jus in Bellum. Even if there wasn’t a clear division like Kant’s; medieval scholars, such as St. Augustine, in his book The City of God, linked war to the post-war goal of peace, introducing war as a tragic necessity to restore the moral order. Additionally, Francisco de Vitoria of the School of Salamanca introduced the principle of proportionality and the rights of non-combatants. Meanwhile, On the Law of War and Peace, Hugo Grotius revisited and introduced just war theory through principles of natural law, including rules on war termination, like good faith and interpretation, arguing that international society requires legal stability even between enemies (Stahn, 2007, p.313). In the 18th century, this natural law base was revisited by Christian von Wolff in the concept of «World Commonwealth» (Civitas Maxima), and Emer de Vattel towards «Voluntary Law of Nations,».

Jus post bellum was initially the subject of limited academic debate, not becoming relevant until the early 21st century in moral philosophy and international law. It started to take shape with academic work in the 1990s, such as Michael Schuck’s 1994 article «When the Shooting Stops: Missing Elements in Just War Theory» where he proposed three principles, such as repentance, honorable surrender, and restoration. Authors like Brian Orend expanded on this theoretical basis with his essay, «Jus Post Bellum”, introducing five-six formal criteria for justice after war, which he continued to develop in his 2007 article for the Leiden Journal of International Law (Rojas, 2021, p.11). During that same year, 2007, the Grotius Centre for International Legal Studies at Leiden University started a project called the Jus Post Bellum Project, which ended up with various publications. In 2008, it’s published Jus Post Bellum: Towards a Law of Transition from Conflict to Peace, in 2014, titled «Jus Post Bellum: Mapping the Normative Foundations,» (Rojas, 2021, p.12). Additionally, “After War Ends: A Philosophical Perspective,» by Larry May and published by Cambridge University Press in 2012.

1. Jus Post Bellum within Contemporary Law

In the article titled «International Humanitarian Law, Jus Post Bellum and Transformative Justice,» Wendy Lambourne argues that International Humanitarian Law (IHL) and International Criminal Law (ICL) are «integrally linked» within jus post bellum, thereby highlighting a critical intersection of norms (2024, pp. 1266). As Mfuranzima (2024) suggests, even when the debate still centered on whether jus post bellum functions as a direct extension of IHL or as a distinct legal framework, there is certainty that a close correlation exists between the two regimes.

International legal instruments regulating the end of the application of International Humanitarian Law remains significantly more ambiguous than identifying its beginning. Broadly, under the Geneva Convention IV (GC IV) and The Hague Regulations, IHL is generally considered to cease at the general close of military operations (Grignon, 2014). Nevertheless, the jurisprudence established in the Tadić case, the application of IHL continue beyond the cessation of active hostilities until a conclusion of peace is reached. Modern legal scholarship argues that in cases of protracted conflicts, the end of IHL applicability is not marked by a mere pause in fighting, but rather by a formal peace treaty, a definitive armistice, or a stable political settlement. As ICTY mentions, each of the four Geneva Conventions contains language intimating that their application may extend beyond the cessation of fighting (Mfuranzina, 2024). For Milanovik, the applicability of IHL should be understood through a functional approach, whereby different rules cease to apply according to their specific purpose (2015, p.170).

The problem of defining exactly when a conflict ends and the transition period begins makes jus in bello almost inseparable from jus post bellum. Although theorists have argued that International Humanitarian Law (IHL) is limited to the duration of armed conflict, certain ongoing obligations prevent IHL from ceasing immediately upon the end of hostilities. For instance, the obligation to repatriate Prisoners of War (PoWs) remains a legal requirement even after the official end of hostilities. Article 118 of the Third Geneva Convention, concerning the release and repatriation of PoWs, continues to exert legal force well beyond the formal end of military operations, as it is based on the best interests of prisoners of war to be repatriated. Scholars such as Lambourne also propose the management of the disarmament process and the disposal of mines and small arms as obligation in the aftermath (2024, p.1265). Under IHL, parties must identify and remove landmines and unexploded ordnance once combat ends, a requirement made explicit in instruments addressing landmines and explosives, namely the Ottawa Treaty (Mine Ban Treaty) and Protocol V to the Convention on Certain Conventional Weapons (CCW).

The application of IHL is not restricted to International Armed Conflicts (IACs); as established in the Tadić jurisdictional transition, it also encompasses Non-International Armed Conflicts (NIACs) when they meet the dual criteria of protracted intensity and organizational structure of the parties involved. Consequently, the temporary criteria present in different IHL legal instruments could differ in the aftermath depending on the conflict’s nature. “This complexity is exacerbated with regard to NIACs by the structural differences between IACs and NIACs and the almost complete lack of any textual guidance.” (Milanovik, 2015, p. 175). The wide range of conflicts, with its distinctive characteristics, brought the relevance for analyzing its development. ‘‘The way a war is fought and the purpose at which it aims, including the peace that is sought for the end of the conflict, are not unrelated, whether in practical or in moral terms.’’ (Williams y Caldwell, 2006, P. 314.). Mfuranzima (2024) introduces jus post bellum as a direct legal consequence of armed conflict and a new normative framework focused on linking it to both jus ad bellum and jus in bello (2024, p. 1262).

Nevertheless, the absence of comprehensive regulatory frameworks renders the position of jus post bellum ambiguous within contemporary international law. As Oreond (2007) argued, jus post bellum originated as a natural extension of modern just war theory, emphasizing the moral assessment of conduct in war and its implications for the structure and justice of post-conflict settlements. However, its development as an official branch has not evolved as well as its counterpart; The Hague Conventions of 1899 and 1907 codified jus in bello, establishing early limits on the «means and methods» of warfare to ensure that the right of belligerents to injure the enemy is not unlimited. Meanwhile, jus ad bellum was modernized through the UN Charter, specifically Article 2(4), which prohibits the threat or use of force against the territorial integrity of states. Caldwell (2006) point out, the Just War tradition implies the existence of norms applicable to the aftermath of war, although jus post bellum has not been formally codified in binding legal instruments.

The difference in its legal development does not appear to be a barrier for authors beginning to rethink this branch. According to Chayes, this renewed academic interest seems to stem from a more self-protective motivation: “The international community has an interest in preventing violence from recurring or spreading, especially when states have invested ‘blood and treasure’ in ending the violence” (2013, p. 292). The traditional tendency to associate fairness with the idea of justice in favor of the party that fought a just and lawful war has been replaced by an approach that applies equally to all parties to a conflict. The critique is grounded in the idea that the terms of peace were essentially determined by a bargaining process among the victors over the rights and obligations of the vanquished. As Williams and Caldwell note, “It should be obvious that winning a just war does not guarantee a just peace, and taking advantage of a victory to subjugate a people and to violate human rights is a grave injustice no matter which side, aggressor or defender, is responsible” (2006, p. 317).

Currently, the debate regarding the relevance of the post-conflict period in international law is linked to ensuring protection and mitigating the risk of return to violence. “The goal of all should be the establishment of a just and lasting peace. Therefore, the long-term consequences of even a justified use of force require that just intention extend into the post bellum stage.” (Lasiello, 2004, p.7). Classical philosophers sought to apply traditional jus ad bellum principles, to define the post-conflict phase. By contrast, modern scholars, such as Orend in the article “Jus Post Bellum: The Perspective of a Just-War Theorist,” reconceptualize just war theory by arguing that the moral legitimacy of war depends not only on how it is fought but also on the justice of the peace that follows. The recent interest in the regulation of this time is centered on the idea that IHL provisions and other international legal texts are not sufficient to build a lasting peace, which is the main motivation to regulate this branch. “The absence of postwar vision negated, for all practical purposes, any hope of a just and lasting peace” (Lasiello, 2004, pp. 38-43)

2. Environment and Jus Post Bellum

Environmental concerns have not been popular in just war theory. As Meisels acknowledged, “the law of armed conflict has primarily focused on regulating the conduct of hostilities,and does not contemplate environmental regulations to apply during and after armed conflict.” (2025, p. 620). However, in recent decades the ecological concerns of armed conflict have been brought to the forefront of the international legal agenda. The International Court of Justice (‘ICJ’) in its Legality of the Threat or Use of Nuclear Weapons Advisory Opinion mentioned that “the environment is not an abstraction but represents the living space, the quality of life and the very health of human beings, including generations unborn.” (I.C.J. Reports, 1997).

Formerly, environmental protection and restoration were put aside in the conflict arena. It is is not until the late twentieth century, after the environmental devastation caused by the First Gulf War and the Vietnam War, that the need to protect the environment is introduced as an independent concern (Meisels, p. 402). It based in the hard truth that the environment is involuntarily linked to military operations “When armed conflict breaks out, the environment is equally present in war as it is in peace.”(Payne, 2017). Environmental degradation during conflict is often unavoidable, as both ecosystems and affected populations are rarely in a position to prevent or contest harmful activities before they occurred “armed conflict is inherently destructive, and the environment cannot be disassociated from military operations”( Biggerstaff & Schmitt, 2023, p.118). Recently, the legal international framework seems to consider some prohibitions during wartime, such as the the ENMOD Convention and Additional Protocol I to the Geneva Conventions.

Österdahl and Zadel (2009) argued that environmental concerns must be considered throughout the armed conflict cycle , but specifically in the post-war period. The first part, it introduced just postbellum not only as merely a means of facilitating an “exit” from conflict, but also as enabling sustainable and lasting peace. “A primary motivation for including protection of environment and natural resources in the law of armed conflict (‘LOAC’) and post- conflict legal regimes (jus post bellum) is to establish productive, peaceful societies.” (Payne, 2017, p.40). The integration of environmental protection into jus post bellum thus represents a recent but significant development in academic research. As noted by Eric De Brabandere, there is broad consensus on the necessity of genuine reconstruction processes in post-conflict settings (2010, pp. 170-173). Especially when environmental harm caused during armed conflict produces long-term consequences that persist well beyond the cessation of hostilities.

The association between jus post bellum and sustainable peace aligns closely with the idea of environmental protection. “Environmental integrity is essential to breaking cycles of conflict, restoring societies, and re-establishing the rule of law” (Payne, 2017, pp. 64-67). Competition over natural resources has been identified as a major driver of civil wars, which have become the predominant form of armed conflict since 1945. As highlighted by Carl Bruch, environmental exploitation and degradation are often not merely consequences of conflict but also underlying causes (2017, p.30). In post-conflict scenarios, unresolved tensions over resource governance may lead to renewed violence, particularly where there is a lack of cooperation in the management of shared natural resources. “The environmental degradation could be a crucial factor in contributing to the outbreak of the conflict” (Homer, 2013). Even in cases where conflicts do not initially arise from environmental factors, the degradation of ecosystems and the loss of natural resources can exacerbate instability and increase the likelihood of future conflict.

Natural resources, as emphasized by Carl Bruch, play a crucial role in economic recovery “Most post-conflict economies depend on natural resources to rebuild and to provide government revenues.” (Bruch, 2017) Particularly in countries with an economy based in natural resources, such as Sierra Leone, where 72 percent of the country’s gross domestic product (‘GDP’) came from two new (post- war) iron ore mines. In societies where the economic base is natural resources, the possibility to recover after a war is more complex, mainly because resource-rich countries often experience poor economic diversification (Auty, 1993). Moreover a healthy environment is therefore a precondition for successful and sustainable reconstruction. Environmental damage caused by warfare including oil spills, destruction of landscapes, and loss of biodiversity can severely hinder the possibility to obtain stability.

Until now, the idea of environment has been introduced through the description of natural sources; however, there is no formal or universal definition in international law. Despite the lack of a formal, codified definition of «the environment» within jus post bellum, the framework provides a unique opportunity to harmonize disparate legal regimes “It draws upon renewable natural resources, nonrenewable natural resources, and ecosystems and their services.” (Brush, 2017, p.31). This viewing of the environment not merely as a collection of «natural resources» for economic exploitation, but as a complex system of «ecosystem services,» jus post bellum can move toward a more open objective. May (2012) discusses that the transition from war to peace should not be defined by a return to the status quo ante, but by the establishment of an environmentally hard foundation. Mainly due to the idea that environmental destruction and degradation during conflict can and must be minimized, but it is next to impossible to eradicate it completely.

“By considering the definition of ‘environment’ in broad terms, based on the best science available at the time of interpretation, it should be possible to understand the legal regimes of IHL and jus post bellum consistently with the evolving views of the international community.” (Sjöstedt, 2017, p. 77 )

3. Key Challenges and Proposals

Jus post bellum remains a relatively new concept, which opens the debate about its nature and content. As Charles Kegley and Gregory Raymond argued, “While scholars have argued for centuries about the conditions under which it is just to wage war, far less thought has gone into how to craft a just peace” (1999, p. 243). However, the new academic tendency shows that actual IHL theory is not sufficient to address the complexities of the post-conflict phase, resulting in a need to develop the concept of jus post bellum to regulate the transition from war to peace (Österdahl and Zadel, 2009). In this scenario, environmental protection in jus post bellum may appear to complicate an already insufficiently defined field.

The idea that the post-conflict period currently operates without clear rules, creates opportunity for regulation. Bell argued that, there is an instinct to codify a jus post bellum that would regulate post-conflict dilemmas more clearly and effectively (2012, p. 52). Nevertheless, several other scholars suggest that jus post bellum should be understood as a framework of guiding principles that inform the content of peace agreements rather than as a strictly codified body of law. Eric De Brabandere conceptualizes jus post bellum more broadly as a systemic notion encompassing the range of norms applicable during the transition from conflict to peace (2010, pp. 141–145). From this perspective, jus post bellum is not the same as its counterparts (jus ad bellum and jus in bello) but may instead evolve as a more adaptive and integrative framework capable of addressing emerging challenges, including environmental ones.

As Sjöstedt argued, “The transition from conflict to peace is often characterized by the lack of governmental control and institutional collapse” (2017, p. 78). Overlooking this development would mean missing its considerable potential, especially for environmental purposes. “Furthermore, in the aftermath of an armed conflict, most stakeholders involved in rehabilitation and restoration are mainly focused on humanitarian assistance and democracy issues, while the environment is a low priority.” (Payne, 2013, p. 18). Even when it may be idealistic to envision a strict set of legal rules governing post-conflict environmental issues, there are alternatives to connect jus post bellum and environment. In the article «The Ability of Environmental Treaties to Address Environmental Problems in Post-Conflict,» the author argued that “Environmental treaties may be able to ensure that some environmental protection work can be carried out despite institutional collapse and lack of governance.” (Sjöstedt, 2017, p. 79)

4. Conclusion (To What Extent Is It Relevant to Rethink Jus Post Bellum from an Environmental Perspective?)

In this sense, jus post bellum has recently gained attention as a framework for thinking more carefully about the aftermath of conflict. Although it is not yet clearly codified and remains under development as an academic field, its relevance in contemporary warfare is increasingly evident, particularly in relation to the integration of environmental considerations into post-war analysis. As Turner Johnson observes, “Perhaps the most difficult problem posed by contemporary warfare, all in all, is the difficulty of achieving a stable, secure ending to it” (Williams and Caldwell, 2006, p. 317). For this reason, the conclusion offers an affirmative answer to the research question.

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