International Law Overview

Principles

Definition

International law is a system of rules, norms, and standards that governs the conduct and relationships between sovereign states, international organizations, and, in some instances, individuals on a global scale. It provides a framework for regulating interactions, promoting cooperation, and addressing issues that transcend national borders, drawing its authority primarily from international treaties, customary practices, and general principles of law.

Ontological type

Sources and Hierarchy

Key Institutions

Enforcement Mechanisms

Key developments

Key Figures

Sovereignty and Codification era

Hans Kelsen[1], associated with the University of Pennsylvania[3] and the University of California, Berkeley[4] in this era, advanced the principle of sovereign equality as a basis for international organization in The Principle of Sovereign Equality of States as a Basis for International Organization[7]. Kelsen[1] argued that Recognition in International Law[8] and Law and Peace in International Relations: The Oliver Wendell Holmes Lectures, 1940-41[9] helped crystallize a codified, state-centered order by clarifying when states are recognized and how peaceful settlement underpins sovereignty. Manley O. Hudson[2], with affiliations at Princeton University[5] and Columbia University[6], produced the Digest of International Law[10] and International Tribunals, Past and Future[11], contributions that structured legal practice and foreshadowed judicial mechanisms essential to enforcing a sovereign, codified order. Together these works anchored the sovereignty-centered, codified international legal order characteristic of this era, reinforcing the role of digests and tribunals as formal modalities for rule-making and enforcement.

Adjudicative Institutionalization era

Ian Brownlie [1] is a leading figure in the adjudicative institutionalization era, with academic stints at Cornell University [3] and the University of Oxford [4]. His key contributions in this era include Principles of Public International Law [7], which articulated foundational norms and procedures; this work helped harmonize adjudication across states and supported the coherence of emerging international courts and treaty regimes, making enforcement more predictable. Robert O. Keohane [2], associated with Harvard University [5] and the Massachusetts Institute of Technology [6], shaped the framing of international governance in this period. The demand for international regimes [8] (1982) proposed the regime approach to cooperation, highlighting how durable patterns of cooperation emerge through institutions, thereby enhancing predictability and vertical integration of international law.

Soft Law and Contestation era

Duncan Snidal [1] is a leading scholar in international governance, anchored at the University of Chicago [3] and The University of Queensland [4], in this era. In Hard and Soft Law in International Governance [7], he argues that hard and soft law are complementary instruments that can steer state behavior through non-binding norms, reputational incentives, and monitoring, a finding pivotal for the soft-law era. Kenneth W. Abbott [2] is affiliated with Princeton University [5] and Cornell University [6], reflecting the era's cross-institutional engagement. In Hard and Soft Law in International Governance [7], he helps develop the shared claim that regulatory diffusion via soft law and judicialization can translate diffuse norms into obligations, a result crucial for managing sovereignty and legitimacy tensions in this period.