Monism vs. Dualism in International Law: Dualist States Require Transformation of Treaties into Domestic Law
Foundational concepts
- Fundamental definition of dualism In international law theory, dualism is the view that international law and domestic (municipal) law are two separate and independent legal systems, each operating in its own sphere; international rules bind states on the international plane, but they are not automatically part of domestic law and require a specific act of transformation or incorporation to have effect internally. Wikipedia grokipedia.com
Source: Monism and dualism in international law – Wikipedia Wikipedia - How monism differs regarding the source of legal authority Monists consider international and domestic law as elements of a single, unified legal order where a basic norm or constitutional rule connects both systems; in many monist theories, international norms can derive validity directly from this single hierarchy. Dualists, by contrast, see two distinct sources of authority—international law deriving from state consent at the international level and domestic law from the state’s constitution and institutions. DiVA Portal grokipedia.com
Source: Monism and dualism in international law – Grokipedia grokipedia.com - Primary historical scholars of dualist theory The classical dualist theory was developed especially by Heinrich Triepel and Dionisio Anzilotti, who argued that international and municipal law are separate orders and that international obligations require transformation into domestic law to be enforceable internally. Cambridge University Press & Assessment grokipedia.com
Source: The Theory of the Law Creators’ Circle – German Law Journal (Cambridge) Cambridge University Press & Assessment - Why international law cannot directly regulate individuals in a dualist system In a dualist system, international law is seen as addressed to states, not individuals; individuals are subject only to the state’s domestic legal order. International norms must be transformed into national legislation before courts can apply them directly to individuals, because until then they lack the status of binding domestic rules in the municipal legal order. grokipedia.com IJCRT
Source: Comparing Monism and Dualism – IJRTI IJCRT - State sovereignty as the foundation of dualism Dualism is deeply rooted in state sovereignty, assuming that each state is the exclusive creator of law for its own territory and population; international law binds states only because they have consented to it, and it cannot penetrate domestic law without a sovereign act (such as legislation) that voluntarily receives or transforms international obligations into the internal legal system. grokipedia.com IJCRT
Source: Monism and dualism in international law – Grokipedia grokipedia.com
The monism vs. dualism debate
- Kelsen’s Grundnorm in monist theory For Hans Kelsen, monism is built on a hypothetical Grundnorm (basic norm) from which the validity of all legal norms—both international and domestic—ultimately derives; in his monism with primacy of international law, this Grundnorm is often formulated as a presupposed norm commanding that states ought to behave as international law prescribes, so domestic legal systems gain validity through conformity with the international legal order. DiVA Portal grokipedia.com
Source: Kelsen on Monism and Dualism – Torben Spaak DiVA Portal - Why dualists say international and domestic law operate on different planes Dualists argue that because the subjects, sources, and addressees of international and domestic law differ—states and treaties/customs versus individuals and statutes/constitutions—the two systems operate on different “planes” or “circles”; conflicts are therefore not between norms of a single system but between rules belonging to separate legal orders, each supreme in its own domain. Cambridge University Press & Assessment IJCRT
Source: Comparing Monism and Dualism – IJRTI IJCRT - Monist approach to conflict between statute and treaty In a monist system, a conflict between a domestic statute and an international treaty is resolved within a single hierarchy: either international law is given primacy (as in Kelsenian monism) or the constitution determines which norm prevails, but courts treat both as part of one system rather than entirely separate orders, often allowing direct application of treaty norms even in the face of conflicting legislation. Wikipedia grokipedia.com
Source: Monism and dualism in international law – Wikipedia Wikipedia - Can a monist state be monist but domestically supreme? A state can be monist in the sense that international and domestic law form a unified order, yet its constitution may still give domestic (constitutional) law formal supremacy over treaties; monism does not logically require international law to be hierarchically superior, only that both sets of norms are understood within a single normative system with a constitutionally determined rule of priority. DiVA Portal grokipedia.com
Source: Monism and dualism in international law – Grokipedia grokipedia.com - Which theory fits a “universal” legal order better? The idea of international law as a universal legal order—a comprehensive system of norms governing all states and, increasingly, individuals—aligns more naturally with monism, especially Kelsenian monism, because it conceptualizes all legal norms as part of one overarching normative structure in which international law provides the ultimate point of reference for validity. Cambridge University Press & Assessment DiVA Portal
Source: The Theory of the Law Creators’ Circle – German Law Journal (Cambridge) Cambridge University Press & Assessment
Practical application and incorporation
- Doctrine of transformation in dualist states The Doctrine of Transformation holds that international treaties and rules do not automatically become part of domestic law; instead, they must be formally transformed—usually by legislation—into national norms before courts can apply them, making this doctrine central to dualist systems where international obligations and municipal law are strictly separated. IJCRT
Source: Comparing Monism and Dualism – IJRTI IJCRT - Doctrine of incorporation in more monist-leaning systems The Doctrine of Incorporation allows international law—especially customary rules and sometimes treaties—to become part of domestic law without specific transforming legislation, either automatically upon ratification or through constitutional provisions, reflecting a more monist orientation in which international norms are directly received into the internal legal order. Wikipedia grokipedia.com
Source: Monism and dualism in international law – Wikipedia Wikipedia - Self‑executing treaties and the monism/dualism blur Self‑executing treaties are treaty provisions that are sufficiently clear, precise, and unconditional to be directly applied by domestic courts without further legislative implementation; their existence blurs the line between monism and dualism because even formally dualist systems may treat certain treaty norms as immediately justiciable, while monist systems may still require legislation for non‑self‑executing provisions. Wikipedia grokipedia.com
Source: Monism and dualism in international law – Grokipedia grokipedia.com - UK Acts of Parliament and dualism The United Kingdom exemplifies dualism because, under its constitutional practice, ratification of a treaty by the executive does not itself make the treaty enforceable in domestic courts; an Act of Parliament is required to transform or incorporate treaty obligations into domestic law, illustrating the dualist insistence on legislative mediation between international and municipal orders. IJCRT
Source: Comparing Monism and Dualism – IJRTI IJCRT - US Supremacy Clause and duality of law In the United States, the Supremacy Clause of the Constitution declares the Constitution, federal statutes, and treaties made under its authority to be the supreme law of the land, meaning certain treaties can have direct domestic effect and override conflicting state laws; at the same time, the distinction between self‑executing and non‑self‑executing treaties preserves elements of dualism by sometimes requiring implementing legislation. Wikipedia grokipedia.com
Source: Monism and dualism in international law – Wikipedia Wikipedia - Treatment of customary international law in dualist systems In many dualist systems, customary international law is either (a) considered part of the common law or general law and thus applied by courts unless overridden by statute, or (b) requires recognition or incorporation through domestic legal doctrine; treaties, by contrast, typically need specific legislative transformation, so customary norms can sometimes enjoy an easier route into domestic adjudication than treaty provisions. IJCRT
Source: Comparing Monism and Dualism – IJRTI IJCRT - Use of unincorporated treaties as interpretive aids Even in strict dualist states, judges are often permitted to use unincorporated treaties as interpretive guides when construing ambiguous domestic legislation, aligning national law with international obligations where possible, while still acknowledging that the treaty itself lacks direct domestic effect absent transformation. Wikipedia IJCRT
Source: Monism and dualism in international law – Wikipedia Wikipedia
International obligations vs. domestic reality
- Article 27 VCLT and internal law as justification Article 27 of the Vienna Convention on the Law of Treaties provides that a state may not invoke the provisions of its internal law as justification for its failure to perform a treaty, meaning that domestic constitutional or legislative conflicts cannot excuse non‑compliance on the international plane, even if they limit domestic enforcement mechanisms. Wikipedia
Source: Vienna Convention on the Law of Treaties – Wikipedia Wikipedia - Duality and the human rights compliance gap The dual separation between international and domestic law contributes to a “compliance gap” in human rights, because even when states ratify human rights treaties, domestic authorities may fail to transform or properly implement them, leaving individuals without effective remedies at home and forcing reliance on international or regional mechanisms that lack direct coercive power. Cambridge University Press & Assessment IJCRT
Source: The Theory of the Law Creators’ Circle – German Law Journal (Cambridge) Cambridge University Press & Assessment - International responsibility when domestic law prevails If a state’s highest court rules that a domestic law prevails over a treaty, the state may still incur international responsibility for breach of its treaty obligations, because under international law the conduct of all state organs—including courts—is attributable to the state, and internal separation of powers cannot be invoked to avoid liability or the duty of reparation. Wikipedia
Source: Monism and dualism in international law – Wikipedia Wikipedia - Investment arbitration tribunals and duality Investment arbitration tribunals such as ICSID generally treat domestic laws and measures as facts against which they apply the relevant international investment treaties; they assess whether domestic regulations violate substantive treaty standards (like fair and equitable treatment or expropriation clauses), making clear that, in case of conflict, the state’s international obligations under the investment treaty prevail for the purpose of the award, regardless of domestic law’s content. Cambridge University Press & Assessment grokipedia.com
Source: The Theory of the Law Creators’ Circle – German Law Journal (Cambridge)) Cambridge University Press & Assessment
Modern challenges and evolutions
- Continuing relevance of the monism/dualism dichotomy In contemporary transnational law, with dense treaty regimes, private standards, and overlapping jurisdictions, many scholars argue that the rigid monism/dualism dichotomy is descriptively insufficient, yet it remains normatively and analytically relevant as a starting framework for understanding how states structure the relationship between international obligations and national law. Cambridge University Press & Assessment
Source: The Theory of the Law Creators’ Circle – German Law Journal (Cambridge) Cambridge University Press & Assessment - EU law as a hybrid “third way” The European Union represents a kind of hybrid or “third way”, because EU law claims autonomy and primacy over member states’ domestic law while also relying on national courts for enforcement; it is neither purely monist nor dualist but operates as a supranational legal order with direct effect and supremacy doctrines that modify traditional dualist conceptions of state sovereignty. Cambridge University Press & Assessment Wikipedia
Source: Monism and dualism in international law – Wikipedia Wikipedia - Constitutional pluralism and the challenge to binary duality Constitutional pluralism is a theory that recognizes multiple overlapping constitutional authorities—for example, national constitutions, EU law, and international human rights regimes—without a single ultimate hierarchical sovereign, challenging the binary monism/dualism view by depicting the legal landscape as a pluralistic network of partially autonomous, yet interacting, legal orders. Cambridge University Press & Assessment
Source: The Theory of the Law Creators’ Circle – German Law Journal (Cambridge) Cambridge University Press & Assessment - Jus cogens and the dualist claim of choice Jus cogens norms—peremptory rules from which no derogation is permitted (such as the prohibitions of genocide or torture)—undermine a strict dualist claim that states are free to choose whether to incorporate international law, because these norms bind states irrespective of consent or domestic implementation and invalidate conflicting treaties and laws at both international and (in practice) domestic levels. Wikipedia grokipedia.com
Source: Monism and dualism in international law – Grokipedia grokipedia.com - Individual as subject of international law and dualism The rise of the individual as a subject of international law—through international criminal tribunals, human rights courts, and direct petition systems—weakens classical dualism by demonstrating that international norms can create rights and obligations directly for individuals, not just states, thereby bypassing the traditional assumption that only domestic law can regulate private persons. Cambridge University Press & Assessment Wikipedia
Source: Monism and dualism in international law – Wikipedia Wikipedia - Climate emergency and monist‑leaning interpretations In the context of the climate change emergency, several domestic courts have increasingly relied on international climate agreements and human rights obligations as interpretive benchmarks or even as quasi‑directly applicable standards, reflecting a more monist‑leaning interpretive practice that narrows the gap between international commitments and domestic judicial enforcement. Cambridge University Press & Assessment
Source: The Theory of the Law Creators’ Circle – German Law Journal (Cambridge) Cambridge University Press & Assessment - The Charming Betsy canon as a bridge The “Charming Betsy” canon, drawn from early US Supreme Court jurisprudence, holds that domestic statutes should, where fairly possible, be interpreted not to conflict with international law, especially the law of nations; this interpretive presumption helps reconcile dualist structures with international obligations by aligning domestic law with international standards without granting treaties automatic supremacy or direct effect in every case. Wikipedia grokipedia.com
Source: Monism and dualism in international law – Wikipedia Wikipedia - Fragmentation of international law and monist unification The increasing fragmentation of international law into specialized regimes—trade, human rights, environment, investment—makes a fully coherent monist unified system difficult to achieve in practice, because differing institutional mandates and interpretive communities generate overlapping and sometimes conflicting norms that resist neat hierarchical integration under a single Grundnorm or constitutional structure. Cambridge University Press & Assessment DiVA Portal
Source: Kelsen on Monism and Dualism – Torben Spaak DiVA Portal - Possibility of a global constitution and dualism A genuine “Global Constitution”—a single, supreme legal framework binding all states and individuals—would require such a degree of centralized authority, judicial hierarchy, and direct effect that it would be hard to reconcile with classical dualism; yet some pluralist and multilevel constitutionalism models suggest that elements of a global constitutional order could emerge incrementally without wholly abandoning the residual autonomy and constitutional identity of states. Cambridge University Press & Assessment grokipedia.com
Source: The Theory of the Law Creators’ Circle – German Law Journal (Cambridge) Cambridge University Press & Assessment
Keywords
Keywords: monism, dualism, international law, Grundnorm, Hans Kelsen, Heinrich Triepel, Dionisio Anzilotti, doctrine of transformation, doctrine of incorporation, self‑executing treaties, state sovereignty, Article 27 Vienna Convention, human rights compliance gap, investment arbitration, EU legal order, constitutional pluralism, jus cogens, Charming Betsy canon, fragmentation of international law, global constitution.
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