Choice of Law

Choice of law is the branch of conflict of laws (private international law) that determines which body of substantive law applies when a dispute touches multiple jurisdictions. It is distinct from jurisdiction (which court can hear the case) and recognition and enforcement (whether a foreign judgment will be honored), though all three are typically analyzed together.

Different legal traditions use different methods:

• Vested rights / lex loci approach — older common law rule applying the law of the place where the relevant event occurred (e.g., lex loci delicti for torts, lex loci contractus for contracts).
• Most significant relationship test — adopted in the U.S. Restatement (Second) of Conflict of Laws (1971), weighing contacts such as place of injury, conduct, domicile, and the parties' relationship.
• Governmental interest analysis — associated with Brainerd Currie, asking which states have a genuine policy interest in having their law applied.
• Party autonomy — in commercial contracts, parties may select the governing law by clause, subject to mandatory rules and public policy limits.

In the European Union, choice of law is largely harmonized by the Rome I Regulation (Regulation (EC) No 593/2008) for contractual obligations and Rome II Regulation (Regulation (EC) No 864/2007) for non-contractual obligations. The Hague Conference on Private International Law also produces instruments, including the 2015 Hague Principles on Choice of Law in International Commercial Contracts.

Courts everywhere reserve a public policy (ordre public) exception allowing them to refuse to apply foreign law that violates fundamental forum values, and many systems distinguish mandatory rules (lois de police) that apply regardless of the parties' choice.

For IR researchers, choice-of-law issues matter in cross-border investment disputes, transnational human rights litigation, sanctions enforcement, and any analysis of how legal fragmentation shapes state and corporate behavior.