The principle of sovereign immunity in international law refers to the concept that a sovereign state cannot be sued before the courts of another state without its consent. This principle is rooted in the idea of the equality and independence of states, and is recognized as a customary norm in international law. Traditionally, sovereign immunity was absolute, meaning that a state enjoyed complete immunity from legal proceedings in foreign courts, regardless of the nature of the act.

However, modern practice has shifted towards the restrictive theory of sovereign immunity. Under this approach, immunity is granted only for sovereign (jure imperii) acts, such as legislation or defense, and not for commercial (jure gestionis) acts, such as trade or contractual transactions. This distinction allows states to be held accountable in foreign courts when they engage in commercial activities similar to private parties.

Many countries, including the United States and the United Kingdom, have codified this principle in their domestic laws, like the Foreign Sovereign Immunities Act (FSIA) of 1976 in the U.S. In India, although there is no specific statute, courts have increasingly recognized the restrictive theory, as seen in cases like Ethiopian Airlines v. Ganesh Narain Saboo (2011).

Thus, the principle of sovereign immunity continues to evolve, balancing state sovereignty with access to justice in cross-border disputes.