In 2024, the International Court of Justice issued provisional measures ordering Israel to prevent genocide in Gaza. Russia has ignored the ICJ's ruling on its invasion of Ukraine. The International Criminal Court has issued arrest warrants for sitting heads of state who continue to travel freely. These are not marginal episodes—they strike at the heart of what international adjudication claims to be. If the most powerful actors can simply disregard international rulings, do these courts possess genuine legal authority, or are they elaborate theaters of aspiration?

Traditional political philosophy offers surprisingly little help here. The dominant frameworks for understanding legal authority were built for domestic contexts, where a sovereign state monopolizes coercive power and courts derive their legitimacy from constitutional arrangements embedded in a shared political community. International courts fit none of these assumptions. They lack enforcement capacity, they operate across radically different legal traditions, and their relationship to democratic consent is, at best, attenuated.

Yet dismissing international courts as merely symbolic misses something important. States do comply with international rulings far more often than the headline-grabbing defiance suggests. International jurisprudence does reshape domestic legal reasoning over time. And the very existence of these institutions has transformed what counts as a legitimate justification for state action on the world stage. Understanding how and why requires moving beyond the domestic analogy and constructing a political theory adequate to the distinctive conditions of global adjudication.

The most traditional account of international court authority rests on state consent. Courts like the ICJ derive their jurisdiction from treaties that states have voluntarily ratified. On this view, international adjudication is simply a sophisticated form of contract enforcement—states agree to be bound, and the court's authority extends no further than the scope of that agreement. This is elegant and familiar, but it generates well-known difficulties. Consent can be withdrawn, reservations can hollow out obligations, and the most egregious violators of international norms are precisely those least likely to have consented to jurisdiction.

A competing account grounds authority in substantive justice. International courts are legitimate because they protect fundamental human rights and enforce norms that possess moral authority independent of state consent. This is the implicit logic behind institutions like the International Criminal Court, which claims jurisdiction over crimes against humanity regardless of whether the accused's state has ratified the Rome Statute. The difficulty here is obvious: whose conception of justice? The charge of moral imperialism is not merely rhetorical—it reflects genuine disagreement about the universality of the norms international courts claim to apply.

A more pragmatic tradition emphasizes coordination. International courts are authoritative because they solve collective action problems that states cannot resolve bilaterally. Trade disputes, maritime boundaries, investment protections—these require stable, predictable adjudication to sustain the cooperative frameworks on which global order depends. Authority, on this account, is functional rather than moral. Courts are legitimate insofar as they produce better outcomes than the available alternatives.

Finally, there is the expertise account, which holds that international courts possess a form of epistemic authority. Their judges are specialists in international law, capable of interpreting complex treaty regimes and customary norms with a sophistication that domestic courts and political actors cannot match. This mirrors Joseph Raz's service conception of authority—international courts are legitimate when following their directives better enables states to comply with the reasons that already apply to them.

None of these accounts is sufficient alone. The most defensible theory of international court authority is likely pluralistic—different sources of legitimacy operate with varying force across different institutional contexts. The ICJ's advisory opinions draw on expertise and coordination; the ICC's criminal jurisdiction invokes substantive justice; the WTO's dispute settlement mechanism rests primarily on consent and coordination. Recognizing this pluralism is not theoretical weakness. It reflects the genuine complexity of global legal ordering, where no single principle of legitimacy commands universal assent.

Takeaway

International court authority cannot rest on any single foundation. Its legitimacy is pluralistic—different courts draw on different combinations of consent, justice, coordination, and expertise, and the strength of their authority varies accordingly.

The European Court of Human Rights developed the margin of appreciation doctrine to navigate a persistent tension: how can an international court apply universal human rights standards while respecting the legitimate diversity of domestic legal and cultural traditions? The doctrine grants states a degree of discretion in how they implement Convention rights, with the margin varying according to the nature of the right, the degree of European consensus, and the quality of domestic deliberation. It is one of the most intellectually fertile—and contested—ideas in international law.

At its best, the margin of appreciation embodies a sophisticated form of epistemic humility. International judges, however expert, are not better positioned than domestic institutions to determine the precise balance between, say, religious expression and public order in a particular national context. Domestic legislators and courts possess local knowledge, democratic accountability, and cultural understanding that no international tribunal can replicate. Deference, on this view, is not abdication—it is recognition that legitimate judgment requires information and standing that international courts structurally lack.

At its worst, however, the doctrine becomes a mechanism for selective abdication. If the margin is too wide, the court effectively permits precisely the violations it was designed to prevent. Minority rights, in particular, are vulnerable—domestic majorities may have little incentive to protect them, and the very purpose of an international human rights court is to provide external accountability when domestic processes fail. The margin of appreciation can become a euphemism for looking away.

The deeper philosophical question concerns the relationship between universality and pluralism. If human rights are genuinely universal, they should apply regardless of local variation. But if they admit of reasonable disagreement in application, some deference to domestic interpretation is not merely pragmatic—it is principled. Martha Nussbaum's capabilities approach offers one way through this tension: certain core capabilities are non-negotiable, but the institutional forms through which societies secure them may legitimately vary. An international court's task, then, is to distinguish between diversity in implementation and failure to protect the substantive core.

What emerges is that deference is not a binary choice but a structured continuum. The appropriate margin depends on the nature of the right at stake, the quality and inclusiveness of domestic deliberation, the vulnerability of affected populations, and the degree of international consensus. Courts that articulate these criteria transparently—rather than deploying deference as an ad hoc escape valve—strengthen both their own legitimacy and the legitimacy of the domestic institutions they review.

Takeaway

Deference is not a retreat from judgment but a form of judgment itself. The crucial question is not whether international courts should defer to domestic systems, but whether they can articulate principled criteria for when deference is warranted and when it becomes complicity.

The most persistent objection to international courts is brutally simple: they cannot enforce their own rulings. The ICJ has no police force. The ICC depends on state cooperation to arrest suspects. The WTO can authorize retaliatory tariffs, but compliance ultimately rests on the willingness of sovereign states. For theorists in the Austinian tradition—where law is the command of a sovereign backed by sanctions—this means international courts are not genuinely legal institutions at all. They issue opinions that powerful states follow when convenient and ignore when not.

But this objection assumes a model of legal authority that even domestic legal systems do not fully satisfy. As H.L.A. Hart argued, the foundation of any legal system is not coercive enforcement but social acceptance of rules of recognition—the shared practices through which officials and subjects identify valid legal norms. International courts, on this view, can possess genuine legal authority if their decisions are accepted as authoritative within the relevant community of practice. The question is empirical and sociological, not merely philosophical: do states, international organizations, and legal professionals treat these rulings as binding?

The evidence is more favorable than skeptics suggest. Compliance rates with ICJ judgments, for instance, are surprisingly high when measured across the full range of cases rather than only the high-profile defiances. The WTO dispute settlement mechanism has achieved remarkable compliance precisely because states recognize that the system's integrity serves their long-term interests. Even non-compliance generates reputational costs that constrain future action—a state that ignores an international ruling signals unreliability to potential treaty partners, investors, and allies.

More profoundly, international courts exercise authority through what might be called discursive power. Their rulings reshape the terms in which international disputes are framed and contested. Once the ICJ has characterized a particular state action as a violation of international law, the burden of justification shifts. States must engage with that characterization—they cannot simply assert sovereign prerogative as if no ruling existed. This is a form of authority that operates through meaning rather than force, but it is no less real for that.

The deepest insight may be that international legal authority is developmental rather than static. Domestic legal systems did not spring into existence fully formed with complete enforcement capacity. They evolved over centuries through iterative cycles of norm articulation, partial compliance, institutional learning, and gradual consolidation. International courts may be at an earlier stage of this trajectory. Judging them against the standard of a mature domestic legal system mistakes a snapshot for a verdict. The relevant question is not whether international courts currently possess the full attributes of legal authority, but whether their practices are building the institutional and normative infrastructure from which such authority can emerge.

Takeaway

Coercion is not the essence of legal authority—acceptance and discursive power are. International courts may lack enforcement mechanisms, but their capacity to reshape justificatory standards and impose reputational costs constitutes a genuine, if still developing, form of legal authority.

International courts resist the categories that political philosophy has traditionally relied upon. They are not sovereign, not democratic in any straightforward sense, and not backed by coercive power. Yet they are not merely decorative either. They exercise a form of authority that operates through consent, expertise, discursive framing, and the slow accumulation of institutional credibility.

The theoretical frameworks adequate to these institutions must be pluralistic about legitimacy, nuanced about deference, and developmental about enforcement. No single domestic analogy captures what international adjudication is or what it is becoming. Political theorists who insist on evaluating global institutions against the template of the nation-state will consistently misunderstand them.

The philosophy of international courts ultimately asks us to reconsider what legal authority requires. If it demands nothing less than a sovereign with a monopoly on force, then most of human legal history—including the early development of the domestic legal systems we now take for granted—fails the test. A more productive approach treats authority as a spectrum, and asks what conditions move international courts further along it.