The consent-based theory of international law is fundamentally flawed: it fails as both a theoretical foundation and a practical tool for legitimising the international legal order. Yet, this argument demands consideration of the strongest objections to be convincing, and even when these are addressed, the case against consent, in my view, emerges with substantive force.

The first pillar of the consent theory rests on treaties as expressions of voluntary agreement between sovereigns. Defenders of this view contend that formal treaty procedures (signature, ratification, domestic parliamentary scrutiny, and the capacity to lodge reservations) create genuine voluntary commitment and bind states only to obligations they have explicitly accepted. Contemporary consent theorists like Brunnée and Toope argue that international law rests not on bare voluntarism but on "interactional law" grounded in shared legal practice, whilst Besson defends a democratic consent framework mediated through representative institutions. These reformulations, however, cannot salvage the theory when confronted with systematic structural coercion masked by legal formalism. Consider the OECD Model Tax Treaty, which governs over eighty percent of bilateral tax agreements between developed and developing countries. Developing nations naturally prefer the UN Model Treaty, which offers substantially greater taxing rights for capital-importing states and thus better protects their fiscal sovereignty. Yet Kenya, Botswana, and Zambia remain exceptions to this precisely because most developing states capitulate to OECD standards set by Euro-American centrism. This capitulation occurs not through deliberate choice but through significant structural favoritism of that outcome, which in many ways constitutes structural coercion. Developing countries lack adequate negotiating teams, possess inferior technical expertise, and face implicit or explicit threats of capital flight, investment withdrawal, and exclusion from developed country markets if they resist. The "consent" to unfavorable tax terms is thus in the formalist sense voluntary, but, in reality, is substantively coerced. Whilst some might contend that states could refuse these terms, doing so invites economic punishment, a consequence indistinguishable from duress in the law of contract. Moreover, whilst developing states occasionally negotiate favorable terms or form coalitions to resist developed country preferences (examples being the Doha Declaration and climate finance commitments), these exceptions prove the rule: consent operates meaningfully only when states possess genuine alternatives and roughly equal bargaining power. The consent framework cannot accommodate pervasive structural inequality without collapsing entirely.

The application of consent to customary international law presents an even graver problem, though proponents argue that the persistent objector doctrine proves consent remains operative in custom formation. More than hundred new states have emerged since 1945, and each is automatically bound by pre-existing customary norms without participating in their formation. A newly independent state becomes instantly subject to rules of international responsibility, maritime delimitation, and territorial acquisition created before its existence, purportedly because these customs exist "for the international community as a whole". Defenders of customary law insist that new states implicitly consented by joining the international community and that the persistent objector doctrine permits them to escape binding rules through timely objection. Yet, this defense fails on multiple grounds. First, the doctrine protects only established objectors who maintained opposition during norm formation, not new states formed after crystallisation. The UK's persistent objection to fisheries jurisdiction rules and Japan's objections to whaling restrictions succeeded because these states objected during the formative period; newly independent states possess no equivalent opportunity. Second, even for existing states, the doctrine requires maintenance of objection across an unknowable temporal window determined retrospectively. States cannot know precisely when a norm has crystallised or whether their objection falls within the permissible period of such a purview. Third, the persistent objector doctrine itself possesses no clear foundation in state practice or opinio juris (a legal belief that a practice is required by law), meaning it fails to satisfy the very consensual criteria it purports to defend. The result is that new states are bound by laws they had no realistic opportunity to refuse, directly marring any meaningful conception of consent.

Third, the consent framework is actively undermined by institutional mechanisms that bind states without their participation by putting other states on a legal pedestal. The UN Security Council, acting under Chapter VII of the Charter, imposes legally binding resolutions on all member states regardless of whether they voted affirmatively. Sudan's referral to the International Criminal Court exemplifies this problem. Sudan signed but never ratified the Rome Statute and explicitly rejected ICC jurisdiction over Sudanese nationals. Yet Security Council Resolution 1593 in 2005 referred the Darfur situation to the ICC, obligating Sudan to cooperate with ICC investigations and allowing prosecution of Sudanese nationals for crimes occurring on Sudanese territory. Sudan possessed no veto power, participated in no negotiation, and had explicitly manifested non-consent to ICC jurisdiction, yet Sudan is now bound by obligations to an institution it rejected. Defenders argue that Sudan consented to the UN Charter and thus to Chapter VII enforcement mechanisms when it joined the UN in 1956. Yet, informed consent demands that the consenting party understood and accepted the specific obligations to which they would be bound. Sudan could not have consented in 1956 to referral to an institution (the ICC) that did not exist until 2002, regarding obligations (cooperation with ICC investigations) it could not have anticipated, under circumstances (Chapter VII referral despite explicit rejection of ICC jurisdiction) it had no reason to foresee. The temporal gap and unpredictability of future Chapter VII determinations render the claim of any meaningful consent untenable. If joining an international organisation constitutes binding consent to all future determinations by institutional majorities, including obligations to entities that did not exist at the time of joining, then in many instances, consent has become indistinguishable from subjection to power exercised through institutional procedures.

Fourth, defenders of consent theory have retreated into increasingly baroque reformulations to defend their model: "implied consent," "tacit consent," "remote consent" through Charter membership, "constructive consent," or "secondary consent to the processes of law-formation". These concepts do have legitimate analogues in domestic legal systems (contract law recognises implied-in-fact agreements; property law accepts adverse possession through constructive consent), and their existence might at first suggest that consent remains a sophisticated analytical tool married with some contextual application. Yet the proliferation of consent modalities in international law reveals that the theory has become unfalsifiable. When "consent" can mean a state's failure to object within an unknowable temporal window, as in a single act of joining an organisation decades earlier or in the participation in a process created without that state's input, then the concept has lost any determinate content. A genuinely falsifiable theory must specify conditions under which a state is not bound, yet the consent theory cannot. For every instance of binding law, scholars retrofit some modality of consent to explain it; for every instance of non-binding law, they invoke consent to a meta-rule authorising that non-binding status. The theory explains everything and therefore explains nothing. Moreover, the domestic law analogues fail upon closer inspection. Implied-in-fact contracts require evidence of mutual assent through conduct; adverse possession requires open, notorious, and continuous possession with knowledge by the true owner; corporate implied authority requires reasonable reliance by third parties. Each domestic analogue places a high bar to prevent the doctrine from expanding infinitely. International law's consent modalities do not have this high bar. "Tacit consent" is inferred from silence alone; "remote consent" persists across decades without renewal; "constructive consent" operates without any conduct whatsoever. The result is that "consent" in international law means whatever lawyers need it to mean to justify desired outcomes.

The most serious objection to abandoning consent theory is that despite its imperfections, it legitimates the international order and protects state sovereignty against hegemonic domination. Replacing consent with a brazen display of power relationships would eliminate even the rhetorical protection weaker states currently possess. This argument has initial force but ultimately fails. A legal order based on engineered consent provides rhetorical cover for hegemonic rule by creating the illusion that weaker states consented to their own subordination. In reality, these states are subordinated whether or not the order claims to rest on consent. Consider again the tax treaty example: when developing states argue these treaties violate their fiscal sovereignty or when developing countries complain about carbon taxes, developed states respond that these agreements are "freely negotiated" and "consensual". If the international legal order openly acknowledged that binding law flows from institutional authority and the geopolitical dominance of the strong over the weak, weak states could construct arguments based on justice, equity, and democratic reform rather than exhausting themselves maintaining the pretence that they consented to arrangements they did not. 

In conclusion, international law derives its binding force from institutional authority, geopolitical power, and universal values that are almost set in stone before many states were even born. This trinity transcends consent altogether. The widespread propagation of the consent rhetoric reflects not the theory's validity but its value for the politically expedient to legitimise deception. An honest account of international legal obligations would expose the true sources of binding force and enable reform efforts grounded in justice rather than in the enticing yet duplicitous claims of consent, best described as a feature than as the foundation of international law.