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Jus post bellum and the ethics of peace

By Carsten Stahn, Jennifer S. Easterday, and Jens Iverson


Whenever there is armed conflict, international lawyers inevitably discuss the legality of the use of armed force and the conduct of the warring parties. Less common is a comprehensive legal analysis, informed by ethics and policy concerns, of the transition from armed conflict to peace. The restoration of peace after conflict is often sidelined in post-conflict legal analysis. Interventions and peace operations seeking to build a just and sustainable peace frequently suffer from a misalignment between ‘means’ and ‘ends.’ There can be stark discrepancies between the immediate reaction to conflict and post-conflict engagement. It is true that concepts such as ‘humanitarian intervention,’ the ‘Responsibility to Protect,’ (R2P) or the ‘protection of civilians’ (POC) have been used to establish capacity and political will to respond to atrocity situations. But attention shifts quickly to other situations of crisis once a cease-fire or peace agreement has been reached. Some of the underlying premises of engagement, such as ideas of responsibility or the ethics of care, receive limited attention in the aftermath of crisis and during the lengthy process of peacebuilding.

An old idea that seeks to mitigate these dilemmas is the concept of jus post bellum. The basic idea emerged in classical writings (e.g., Alberico Gentili, Francisco Suarez, Immanuel Kant) and has its most traditional and systemic rooting in just war theory. In this context, it is part of a structural ‘framework’ to evaluate the morality of warfare, and in particular the ‘right way to end a war’, including ’post-war-justice’ (Michael Walzer, Brian Orend). Outside just war theory, jus post bellum is largely unexplored. The notion was used sporadically in different contexts over the past decade: peacebuilding and post-conflict reconstruction, transformative occupation, transitional justice, and the law of peace (lex pacificatoria) more generally. But the concept has lacked consistency; there are almost as many conceptions of jus post bellum as scholars, within and across disciplines.

A modern understanding of jus post bellum requires a fresh look at each of the core components of the classical concept, namely the meanings of ‘jus,’ ‘post,’ and ‘bellum.’ In traditional scholarship, jus post bellum has mostly been understood as ‘justice after war’. However, in modern scholarship, the concept of ‘jus’ is debated. Does it mean ‘law,’ ‘justice,’ or a complicated mix of the two? The concept of time and what it means to be ‘post’ conflict, and even that of ‘war’ itself, with blurred distinctions between modern armed conflicts, are now more and more contested.

destroyed brick house

Functions of jus post bellum

Classical scholarship tied jus post bellum to the vindication of ‘rights’ and ‘duties,’ military victory, and the distinction between ‘victors’ and ‘vanquished’. Today, such conceptions require re-consideration. The experience of the two World Wars has confirmed the Kantian postulate that peace remains fragile if it contains tacitly reserved matter for a future war’ (Perpetual Peace). But in modern conflicts (e.g. Afghanistan, Iraq), the entire concept of ‘victory’ has become open to challenge.

Insights from contemporary conflict research indicate that it is not enough to deal with the formal ending of conflict or the ‘pacification’ of violence. Distinctions between ‘winners’ and ‘losers’ become muddied, making it more difficult to mitigate the risk of a return to violence. Structural approaches to peacebuilding require engagement with social injustices, the ‘violence of peace,’ the establishment of ‘trust’ in norms and institutions and other factors that make a society more  ‘resilient’ against conflict.

This makes it necessary to re-think the concept of ‘jus’ beyond its traditional focus on rights and post-war justice (i.e. punishment, responsibility). Past decades have witnessed a rapid rise of the ‘liberal justice model’ and norms and instruments of criminal justice. Core challenges of modern transitions lie therefore not so much in the definition of proper accountability mechanisms, but rather in their coordination with other rationales and priorities (i.e. protection of socio-economic rights) and their perception as elements of ‘just peace.’ This creates space for a modern function of jus post bellum. A modern jus post bellum may pursue different rationales beyond rights vindication or punishment:

(i) it may have a certain preventive function, by requiring actors to look into the consequences of action before, rather than ‘in’ and ‘after’ intervention.
(ii) it may serve as a constraint on violence in armed conflict; and
(iii) it may facilitate a succession to peace, rather than a mere ‘exit’ from conflict.

System, framework, or interpretative device?

The branding of jus post bellum as a modern concept comes with its own problems and politics. The very use of the label creates some risks (e.g. fears of abuse and instrumentalization) and concerns relating to the function and reach of law. But there is some space to ‘think outside the box.’ A modern jus post bellum does not necessarily have to be framed in the structure and form of established concepts, such as jus ad bellum or jus in bello. There is virtue in diversifying the foundations of jus post bellum.

First, Jus post bellum may be said to form a system of norms and principles applicable to transitions from conflict to peace. It provides, in particular, substantive norms and guidance for the organization of post-conflict peace. Some voices have even called for new codification, i.e. a fifth Geneva Convention. But more law and abstract regulation do not necessarily suffice to address tensions arising in the aftermath of conflict. There may a greater need for a better application of the existing law, and its adjustment to context, rather than the articulation of new norms and standards. Some promise may lie in the strengthening of informal mechanisms and flexible principles.

A second and more ‘modest’ conception of jus post bellum is its qualification as a ‘framework.’ This conception emphasizes the functionality of jus post bellum, such as its capacity to serve an instrument to evaluate action (e.g., legitimate ending of conflict) and to establish a public context for debate. Jus post bellum might be construed as an ‘ordering framework,’ or as a tool to coordinate the application of laws, solve conflicts of norms, and balance conflicting interests.

Thirdly, jus post bellum may constitute an interpretative device. The concept might inform a context-specific interpretation of certain normative concepts, such as ‘military necessity’ or the principle of proportionality. It might, for instance introduce a novel end in relation to the conduct of hostilities, namely the objective not to defeat the goal of sustainable peace through the conduct of warfare.

In moral philosophy, the idea of jus post bellum has been associated with the struggle for ‘justice’ and ‘just peace’ for centuries. It has been driven by ambitions to reconcile ideas of justice and punishment with moderation towards the vanquished. These dilemmas continue today. But underlying tensions have received increased attention in the legal arena since the 1990s. Many of the unexplored strengths and new opportunities lie in the broader role of the concept in relation to peacebuilding. It is here where the concept provides new prospects to rethink some of the fundamental elements of the table of contents and institutions of international law, not necessarily in the form of the ‘liberal’ peace idea, but in a novel, pluralistic way.

Carsten Stahn, Jennifer S. Easterday, and Jens Iverson are the editors of Jus Post Bellum: Mapping the Normative Foundations. Carsten Stahn is Professor of International Criminal Law and Global Justice and Programme Director of the Grotius Centre for International Studies, Universiteit Leiden. Jennifer S. Easterday is a Ph.D Researcher, Faculteit Rechtsgeleerdheid, Instituut voor Publiekrecht, Internationaal Publiekrecht, Universiteit Leiden. Jens Iverson is a Researcher for the ‘Jus Post Bellum’ project and an attorney specializing in public international law, Universiteit Leiden.

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Image credit: Miniature model of a postwar red brick house. © Blooms-Studio via iStockphoto.

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