How is conflict of laws different from public international law?

Conflict of laws and public international law are distinct legal fields with different scopes and origins.

Conflict of laws, often referred to as private international law, consists of rules within a country’s own domestic legal system. It is designed to resolve issues that arise when legal matters—such as contracts, marriage, or torts—involve more than one jurisdiction. These rules determine which court has jurisdiction, which country's laws should be applied, and how foreign judgments are enforced. Because these rules are national in origin, they are explicitly not part of international law, except where countries have established specific treaties.123

In contrast, public international law is an independent legal system that exists outside the domestic orders of individual states. It governs relations between sovereign states, international organizations, and, increasingly, individuals. While conflict of laws addresses private relationships between individuals or corporations, public international law deals with state institutions, human rights, trade, and the reach of state sovereignty. Unlike the national rules of conflict of laws, public international law provides a framework for international interaction and is sustained by reciprocity and common interest among states.214