• Law and politics on the global stage

International law and international relations (IR) have long been intertwined disciplines that seek to explain and shape global behaviour. While international law establishes the formal rules governing states and international actors, IR provides the theoretical frameworks for understanding how and why states behave the way they do. 

Together, they form a symbiotic partnership: Law gives structure and predictability, while politics injects realism and context. The intersection between these two fields is most visible in the way that treaties, customary norms, and legal institutions interact with state interests, power dynamics, and diplomatic strategy. Without international law, the international system would resemble a political jungle; without IR, legal rules would exist in a vacuum detached from political reality. Each discipline complements and deepens the understanding of the other across multiple dimensions of global governance.

Theoretical foundations: Realism and legal idealism

At the heart of IR lies a tension between power and principle. Realists, such as Hans Joachim Morgenthau, argue that international law often functions as a tool that reflects the will of powerful states rather than an autonomous moral force. They maintain that states comply with law only when it aligns with their national interest or strategic advantage. In contrast, idealist and liberal thinkers believe that legal norms have an independent capacity to shape and constrain state behaviour through socialisation, reciprocity, and moral obligation. This theoretical debate highlights that understanding international law requires recognising its dual nature, both as a product of power and as a constraint upon it. For realists, law is secondary to survival; for liberals, it is a means of fostering cooperation and trust in an anarchic world.

The interplay between these theories enriches both disciplines. For international lawyers, incorporating IR theories provides a deeper appreciation of why legal compliance varies across contexts. For IR scholars, legal frameworks serve as valuable evidence of how states institutionalise norms over time. This dynamic explains phenomena such as the gradual acceptance of human rights (HR) norms, even among initially resistant states. It also clarifies why enforcement mechanisms, such as sanctions or diplomatic pressure, often rely on political coalitions. In short, theory bridges the conceptual gap between legality and legitimacy, offering insight into how power and principle coexist on the world stage.

The role of institutions: From the UN to the ICJ

International institutions embody the intersection between law and politics more visibly than any other global structure. The United Nations (UN), for instance, stands as both a legal framework and a political arena where states pursue their interests under the guise of collective security and cooperation. The UN Security Council’s resolutions carry legal force, but their implementation often depends on the political will of its Permanent Members, revealing the tension between equality and power. Similarly, the UN General Assembly provides a forum for norm-building, where developing nations influence global discourse despite lacking military might. This dual nature of institutions shows how international law gains practical meaning through political negotiation and compromise.

Beyond the UN, institutions such as the International Court of Justice (ICJ) and the World Trade Organisation (WTO) demonstrate how law depends on political legitimacy for enforcement. The ICJ can interpret and apply legal principles, yet its judgments rely on voluntary compliance. Likewise, the WTO’s dispute settlement body enforces trade law through mechanisms that combine legal reasoning with political pressure. Even the International Criminal Court’s (ICC) operations reveal how law and politics intertwine, as prosecutions often reflect global power hierarchies. Studying these institutions through both legal and IR lenses helps explain why international law sometimes succeeds in promoting order and at other times appears paralysed by political interests.

Compliance and enforcement: Power and persuasion

One of the enduring puzzles of international law is why states comply without a central authority enforcing rules. IR theory offers insight into this question by emphasising the importance of reciprocity, reputation, and legitimacy. States often adhere to treaties and customary norms to maintain predictability in their external relations and to preserve trust within the international society. Compliance thus becomes a rational strategy rather than mere moral adherence. When states violate norms such as through unlawful invasions or treaty breaches, they risk losing diplomatic credibility and access to cooperation, both of which are politically costly.

However, enforcement mechanisms in international law often depend more on persuasion than punishment. Political coalitions, sanctions, and naming-and-shaming campaigns act as substitutes for centralised authority. The Iraq invasion of 2003 or Russia’s actions in Ukraine show how great powers can challenge legal frameworks, yet still face political isolation and legitimacy crises. Conversely, smaller states rely on international law as a shield against domination, invoking it in diplomatic and judicial forums to protect sovereignty. Thus, compliance and enforcement are best understood as a fusion of legal norms and political incentives, where power shapes obedience, and legitimacy sustains order.

HR and global justice: Law in the service of humanity

The global HR regime illustrates how moral aspirations evolve into binding legal standards through political mobilisation. Following the atrocities of World War II, the Universal Declaration of HR and subsequent treaties institutionalised shared values of dignity and equality. Yet, these norms did not arise in a legal vacuum, they were driven by political momentum and collective outrage. Movements against apartheid, gender discrimination, and torture transformed political activism into codified law. International law provided the structure, while IR supplied the advocacy networks and diplomatic alliances necessary for enforcement.

Despite these achievements, the implementation of HR remains politically charged. Some states invoke cultural relativism to resist international scrutiny, while others selectively apply HR rhetoric for political gain. The effectiveness of global justice mechanisms, such as the ICC or the UN HR Council, often depends on the support of major powers. For instance, interventions in Kosovo or Libya reflected a blend of humanitarian concern and strategic interest. Understanding these contradictions requires combining legal analysis with IR perspectives on sovereignty, legitimacy, and power politics. Thus, HR law’s strength lies not only in its moral foundation but also in its ability to navigate the political realities of the international system.

Globalisation and emerging challenges

Globalisation has redefined the boundaries between domestic and international law, creating a more interconnected but complex legal order. The spread of trade networks, migration, and digital technologies means that local issues increasingly have global consequences. IR scholars highlight how interdependence compels cooperation, while legal experts craft instruments to manage it — such as the Paris Agreement on climate change or the Budapest Convention on Cybercrime. These frameworks demonstrate how the law provides solutions to collective problems, but their success ultimately depends on political consensus. The Covid-19 pandemic, for example, exposed how global governance can falter when political will weakens, even in the presence of clear legal obligations.

Moreover, globalisation has empowered new actors beyond the traditional state system. Multinational corporations, non-governmental organisations, and technology firms now shape global norms on privacy, environment, and digital ethics. This diffusion of authority challenges both international law and IR to adapt. Legal scholars must grapple with non-state accountability, while IR theorists must reconsider who truly wields power in the international system. Together, they provide a comprehensive understanding of how rules evolve in a rapidly changing world. The study of this intersection is therefore indispensable for managing transnational risks that neither law nor politics can handle alone.

The future of multilateralism: A shared destiny

The erosion of trust in multilateral institutions has raised doubts about the resilience of both international law and global cooperation. Rising nationalism and great-power competition have undermined the spirit of collective security that once defined the post-1945 order. Yet, the same global challenges that divide states such as climate change, pandemics, and cyber threats also make collaboration indispensable. International law provides the normative framework for such cooperation, while IR theory explains the incentives and constraints shaping it. This dual perspective is essential for understanding why reforming institutions like the UN or the WTO requires both legal innovation and political compromise.

Looking ahead, the survival of multilateralism depends on rebalancing legitimacy and effectiveness. States must see compliance not as a concession but as a strategic investment in stability. Legal frameworks should become more inclusive, reflecting the voices of the Global South and emerging economies. Political leadership must, in turn, renew faith in international institutions by aligning power with shared values. The interplay of law and politics thus remains central to humanity’s collective destiny, ensuring that global order evolves not through domination, but through cooperation rooted in both principle and pragmatism.

Conclusion: Complementary lenses on global order

International law and IR are two sides of the same coin, each illuminating aspects of world affairs that the other cannot fully explain alone. Law provides the normative compass and procedural order, while IR uncovers the motives and power dynamics underlying state behaviour. Together, they enable a richer understanding of how rules and realities interact in shaping the international system. The study of their intersection is not merely academic, it is essential for navigating the 21st Century’s crises and opportunities. As the world grows increasingly interconnected, bridging these disciplines will remain vital to ensuring justice, peace, and effective global governance.

(The writer is an attorney and a Senior Law Lecturer at the Colombo University.)

–-------------------

The views and opinions expressed in this article are those of the author, and do not necessarily reflect those of this publication