When Domestic Courts Become Global Actors: The New Debate Over Judicial Power in International Law
Domestic courts across the world are no longer just implementing international law - they're actively shaping it. From climate litigation in the Netherlands to corporate accountability cases in the UK, national judges are interpreting treaties, reviewing extraterritorial conduct, and constraining foreign policy decisions in unprecedented ways. This shift has sparked fierce debate: are these courts strengthening international law by filling accountability gaps, or quietly fragmenting it through inconsistent interpretations? This article explores how domestic courts have become unexpected power brokers in the international legal system, and what their rise means for the future of global governance.
For decades, domestic courts occupied a relatively modest position in the international legal architecture. They were the foot soldiers, not the generals - important for implementing treaties domestically, but hardly central to the development or interpretation of the global rules themselves. That era, by any measure, has ended.
Across Europe, Africa, the Americas, and Asia, national courts are increasingly asserting the authority to interpret international obligations, review extraterritorial conduct, and even assess the legality of military or diplomatic decisions taken far beyond their borders. Professor Karen Knop at the University of Toronto described this as "the judicialization of foreign affairs on a scale we've never seen before" - a transformation that has turned domestic courts into unexpected power brokers in international law.
This shift has sparked a serious, and at times heated, debate amongst international lawyers, diplomats, and scholars: Does the rise of domestic judicial power strengthen the international legal order, or does it quietly destabilise it?
The answer, it turns out, depends rather heavily on how one understands the role and limits of international law itself.
The Rise of "Domestic International Law Courts"
The expansion of domestic judicial engagement with international law didn't happen overnight. Rather, three interconnected trends have accelerated the shift over the past two decades.
1. Incorporation and Direct Applicability
Many constitutions now incorporate treaties directly into domestic law, meaning judges cannot simply avoid applying international norms even if they wanted to. "Once you constitutionalise treaty obligations," observes Professor André Nollkaemper at the University of Amsterdam, "you empower courts to interpret those obligations - and they often do so more boldly than international tribunals themselves."
The Dutch Supreme Court's Urgenda climate decision is a striking example. The court held that the government's climate policy violated its obligations under the European Convention on Human Rights - an interpretation that the European Court of Human Rights itself had not yet articulated with such clarity.
2. Judicial Review of Foreign Affairs
Courts are increasingly willing to police executive action in areas once treated as categorically untouchable: arms transfers, diplomatic immunity, military deployments, cybersecurity cooperation, climate obligations, and sanctions regimes. Questions previously reserved for diplomats are now being resolved by judges wearing wigs in courtrooms from London to Nairobi.
Professor Anne Peters at the Max Planck Institute notes that "the traditional doctrine of non-justiciability in foreign affairs has been steadily eroded. Courts are no longer willing to simply defer to the executive when fundamental rights or treaty obligations are at stake."
3. The "Globalised" Litigant
NGOs, activists, multinational companies, and individuals are bringing international law arguments to national courts with increasing sophistication and frequency - and they're often succeeding. These litigants, as Professor Anthea Roberts at Australian National University puts it, are "forum shopping with international law," forcing judges to engage with global norms that were once abstract or distant from everyday legal practice.
The cumulative effect is the emergence of what some scholars call "domestic international law courts" - domestic judicial bodies that increasingly function like quasi-international tribunals, interpreting and applying international law with confidence and, at times, considerable creativity.
The Promise: Democratisation and Accountability
Supporters of this shift argue that domestic judicial engagement doesn't threaten international law - it strengthens it in three important ways.
A. Bringing International Law Closer to the Public
Domestic courts operate in national languages, with public hearings and accessible procedures. When judges apply international norms, they make those norms understandable and enforceable within national legal culture in ways that distant international tribunals rarely can.
"International law has always had a legitimacy problem," argues Professor Eyal Benvenisti that "It's seen as remote, technocratic, the preserve of diplomats. When domestic courts engage with it, they democratise it. They make it relevant to ordinary people's lives."
B. Filling Accountability Gaps
Where international courts lack jurisdiction, resources, or political backing, national courts sometimes fill the void. Universal civil jurisdiction cases, corporate liability litigation, climate cases, and proceedings involving foreign officials have all advanced in domestic forums precisely when international mechanisms fell short.
The UK Supreme Court's decision in Vedanta v Lungowe - which allowed Zambian villagers to sue a British parent company for environmental damage caused by its subsidiary - exemplifies this gap-filling function. "International law simply has no effective mechanism for holding multinational corporations accountable," notes Dr Jennifer Zerk, a corporate accountability specialist. "Domestic courts have stepped into that vacuum."
C. Depoliticising Compliance
Executives may delay or strategically avoid implementing international obligations for political reasons. Domestic litigation, by contrast, can force compliance through judicial mandate - making states live up to their treaty commitments regardless of political convenience.
For scholars in this camp, domestic judicialisation isn't a threat to international law. It's the natural evolution of a more decentralised and responsive international order, one better suited to our interconnected world.
The Concern: Fragmentation and Judicial Overreach
But a growing number of international lawyers - including some quite prominent voices - worry that this trend may be stretching the system beyond its original design, and perhaps beyond what it can sensibly bear.
A. Divergent National Interpretations
International law depends fundamentally on consistency. Yet domestic courts, interpreting the same treaties, often reach incompatible conclusions. Professor Gleider Hernández points to several problem areas: "We're seeing differing standards for state immunity, conflicting views on universal jurisdiction, divergent readings of environmental or human rights obligations, and inconsistent approaches to attribution and extraterritoriality. The result is a patchwork of national decisions that may undermine the uniformity international rules require."
When Germany's courts interpret the Geneva Conventions differently from those in France or the United States, which interpretation governs? The absence of a clear answer creates what Professor Nico Krisch at the Graduate Institute Geneva calls "institutional friction" - a polite term for legal chaos.
B. Judicial Over-extension into Foreign Policy
Foreign affairs, critics argue, require diplomatic flexibility - the ability to negotiate, compromise, and adjust strategy in response to changing circumstances. When domestic courts issue rulings that block arms sales, restrict sanctions regimes, or review military operations abroad, they may constrain governments in ways that diplomats cannot remedy through normal channels.
"Courts are being asked to resolve questions they lack institutional expertise to assess," argues Sir Daniel Bethlehem, a former UK Foreign Office legal adviser. "Should the UK supply arms to Saudi Arabia given the situation in Yemen? That's a question involving military intelligence, diplomatic relations, regional stability, and strategic alliances. It's not obvious that judges are best placed to make that call."
C. The Legitimacy Problem
Domestic courts speak with authority inside their own legal systems - but not internationally. A ruling by the Dutch courts can have significant political effects on Shell's operations globally, or on other states' climate policies, without those states or entities having had any say in the Dutch judicial process.
This raises legitimacy concerns that international tribunals, with their shared and consent-based jurisdiction, were specifically designed to mitigate. As Professor Yuval Shany at Hebrew University observes, "There's a fundamental tension between the democratic accountability of domestic courts within their own systems and their lack of accountability when their decisions affect external actors."
Extraterritoriality: The New Flashpoint
The most contentious cases involve extraterritorial acts - cyber operations, armed conflicts abroad, overseas corporate activity, cross-border surveillance, and environmental harm extending beyond national borders.
Domestic courts are increasingly accepting jurisdiction over these issues. The Belgian courts' investigation of war crimes in Syria, French climate litigation targeting Total's overseas operations, and Canadian courts' review of mining company conduct in Latin America all illustrate this trend.
Supporters say this ensures accountability in a world where actions and harms are transnational. "Borders aren't shields for wrongdoing," insists Professor Sangeeta Shah at Nottingham. "If a company headquartered in London causes environmental devastation in Zambia, why shouldn't English courts have jurisdiction?"
Critics warn it risks what Professor Antonios Tzanakopoulos at Oxford bluntly calls "judicial imperialism" - the projection of one state's legal standards onto others, backed by judicial rather than military power. The result could be diplomatic backlash, inconsistent global standards, and what some fear is a neo-colonial dynamic where powerful states' courts effectively regulate conduct in weaker ones.
The core question becomes: Should one national court shape the legal obligations of another sovereign state? There is, to put it mildly, no consensus.
The ICC Shadow
Interestingly, the International Criminal Court has indirectly contributed to this trend. As debates over its jurisdiction, evidentiary thresholds, and - most controversially - its selective enforcement have intensified, some states and litigants have turned to national courts to pursue accountability instead.
Dr Dapo Akande at Oxford notes that "when international institutions struggle with legitimacy or effectiveness, domestic courts instinctively fill the gap. We saw this with immunity cases, with corporate accountability, and now with international crimes."
This development illustrates a larger, somewhat ironic point: the more troubled international institutions become, the more attractive domestic courts appear as alternative venues for resolving what were once expected to be international legal questions.
Are Domestic Courts Strengthening or Destabilising International Law?
The answer, frustratingly for those who prefer clear conclusions, is neither simple nor singular.
Domestic courts strengthen international law when they clarify treaty obligations through reasoned judgments, enforce norms that might otherwise remain purely theoretical, provide remedies where international courts lack jurisdiction, and enhance democratic scrutiny of foreign policy decisions.
They destabilise international law when they generate inconsistent interpretations across jurisdictions, insert judicial authority into sensitive geopolitical issues beyond their expertise, undermine the principle of sovereign equality between states, and stretch jurisdiction to extraterritorial situations with tenuous connections to the forum state.
What we're witnessing, then, is not a crisis exactly - but a fundamental reconfiguration of international law, one in which domestic courts have moved from the periphery to the centre of how global rules are interpreted, applied, and ultimately shaped.
Towards a New Balance
If domestic courts are to remain credible interpreters of international law without fragmenting the system entirely, several steps may become necessary.
Professor Yuval Shany suggests that clearer guidance on extraterritorial jurisdiction - perhaps through the International Law Commission - could help. Professor Samantha Besson at Fribourg argues for stronger "judicial dialogue" across borders, where courts explicitly engage with each other's reasoning to build convergence rather than divergence.
Others point to the need for harmonised evidentiary and procedural standards, particularly in transnational cases. And nearly everyone agrees on the importance of what Professor Jutta Brunnée at Toronto calls "judicial humility" - a recognition by courts of the limits of their own authority and expertise.
At the same time, as Professor Martti Koskenniemi reminds us, "we must maintain space for diplomatic problem-solving alongside litigation. Not every international dispute benefits from judicialisation."
International law is becoming increasingly decentralised, whether we like it or not. The challenge facing practitioners and scholars alike is ensuring that decentralisation doesn't simply devolve into inconsistency - or worse, into competing and incompatible legal orders.
Conclusion: The System Is Changing - Whether States Like It or Not
Domestic courts are no longer peripheral actors in the international legal system. They are now central to its interpretation, enforcement, and evolution. Whether this ultimately strengthens or fragments international law depends less on the courts themselves and more on how states, litigants, international institutions, and scholars respond to this new reality.
The debate is not about removing courts from foreign affairs - that ship has sailed. It's about finding the right balance between judicial accountability and coherent international governance in a world where legal disputes are increasingly global, complex, and deeply interconnected.
The role of domestic courts is no longer a sidebar in international law. It has become, without exaggeration, one of its most defining debates - and one that will shape the system for decades to come.