DOC 1 Roberts: TRADITIONAL AND MODERN APPROACHES TO CUSTOMARY INTERNATIONAL LAW: A RECONCILIATION

Predictions for Custom
- The demise of custom as a source of international law has been widely forecasted.
- Contentious nature of custom and its elements.
Importance of Custom
- Increasing significance in important areas like human rights obligations.
- Codification conventions, academic commentary, and case law of the International Court of Justice contribute to the contemporary resurrection of custom.
Opposing Approaches
- Two differing approaches:
- Traditional Custom: Focus on state practice, emphasizes the significance of state behavior in interpreting the creation and existence of international law.
- Modern Custom: Centers on opinio juris, the belief states hold regarding the legality of their actions, allowing for quicker evolution of customs through broader interpretations of international treaties and forums.
- Need for a cohesive theory to encompass both approaches.
Key Definitions
- Statute of the International Court of Justice describes custom as "evidence of a general practice accepted as law."
- Elements of customary international law include:
- State Practice: General, consistent actions by states.
- Opinio Juris: Belief that the practice is legally obligatory.
- Difficulties arise in determining belief vs. stated opinion and in interpreting treaties and declarations concerning their status as state practice or opinio juris.
- Anthony D'Amato's distinction: Actions form custom when legality of action is articulated.

Characteristics of Traditional Custom
- Emerges from consistent state practices believed to be legally obligatory.
- Evolves inductively from specific state actions.
- Example: S.S. Lotus (1927) case infers a general custom based on specific actions related to territorial jurisdiction.
Characteristics of Modern Custom
- Derived deductively from general rules articulated by institutions rather than through specific state actions.
- Example: ICJ's Military and Paramilitary Activities in Nicaragua (1986) case where the court bases rulings on General Assembly resolutions rather than strict adherence to state practices.
Tests and Justifications
- Traditional customs develop slowly; modern customs evolve rapidly, creating a dichotomy in legitimacy discussions.
- Perspectives on Legitimacy
- Dinosaur Perspective: Traditional customs are seen as obsolete due to rapid change in the international system.
- Dynamo Perspective: Modern customs offer a progressive legal framework responsive to moral and global challenges.
- Dangerous Perspective: Accusations that modern customs may lead to political and legal abuses.
Critiques of Customary Law
- Arguments about the indeterminate nature of custom and lack of democratic legitimacy concerning its formation.
- Claims that traditional custom serves powerful states and lacks a universal basis for acceptance.

Descriptive Accuracy vs. Normative Appeal
- H.L.A. Hart and R. M. Hare’s definitions differentiate between descriptive (what law has been) and prescriptive (what law should be) statements.
- Legal rules are inherently prescriptive; they demand specific conduct based on normative arguments about what the law ought to be.
Importance
- Descriptive accuracy is essential for creating reliable laws that reflect state actions and for predictive power concerning future behavior.
- Normative appeal highlights the importance of the legitimacy of the processes leading to law formation.
Facilitative and Moral Customs
- Customs fall on a spectrum from facilitative (e.g., traffic rules) to moral (e.g., human rights laws).
Procedural and Substantive Normativity
- Strong procedural requirements enhance legitimacy, whereas substantive moral principles focus on the appropriateness of laws in promoting justice and fairness.
Balancing Both
- The best customs should promote the accurate regulation of human conduct while also embodying collective moral perspectives.

Kirgis and Tasioulas's Proposal
- Each element (state practice and opinio jurias) can be understood on a sliding scale of relevance. Strong practice may suffice without the same strength of opinio juries required for less serious actions.
- Tasioulas rationalizes this approach with Dworkin's interpretive theory to fit legal customs and moral considerations cohesively.
Application of the Sliding Scale
- In Traditional Custom: State practice and legal precedents hold more weight, only needing less affirmation of opinio juris to establish legal customs.
- In Modern Custom: Opinio juries can play a critical role in forming norms that may not yet be firmly established in state practices, allowing for development of moral law over time.
Critiques of the Sliding Scale
- Raises questions about the legitimacy of the criteria determining custom formation vs. substantive norms.
Promoting Reflective Interpretive Theory
- Provides a nuanced methodology that balances description and substantive norms better than a simplistic sliding scale.
- Potential for emergence of adjustable international norms in response to changes in values or real-world practices.

Discussion of the Fluid Nature of Custom
- Emphasis on how customs evolve and the fluidity of customary practices.
- Necessity for customs to reflect contemporary values and ethical standards; for example, justifications for military interventions based on humanitarian crises.
Case Study: NATO in Kosovo
- Examines contradictions and emerging norms of humanitarian intervention post conflict, looking at how NATO's actions may serve as a basis for evolving customary laws.
Conclusion
- The need to maintain a dynamic, reflective system to evolve legal customs that embody shared moral perspectives and enhance global stability and governance.