Visit and search doctrine

The visit and search doctrine is the belligerent power during international armed conflict to stop and inspect a merchant vessel outside neutral waters where the law of naval warfare supplies reasonable grounds. Its purposes include determining the vessel's character, cargo and possible involvement in contraband carriage, blockade breach or unneutral service. It is not a general peacetime power to board foreign shipping.

Operation

A belligerent platform may direct a merchant vessel to stop, examine documents and, when necessary, search the vessel and cargo. If a safe and effective search cannot take place at sea, diversion to an appropriate area or port may be used within the applicable rules. The San Remo Manual also addresses neutral merchant vessels under convoy, for which information supplied by the neutral warship can replace ordinary visit and search in specified circumstances.

Reasonable suspicion does not automatically transfer title or authorise attack. A vessel believed liable to capture is sent for prize proceedings where practicable. Capture and condemnation are separate steps. Resistance, flight and exceptional grounds for attack require their own legal analysis, including precautions and protection of persons on board.

Legal boundary

The San Remo Manual and Newport Manual on the Law of Naval Warfare (2023) are influential restatements prepared by experts; they are not treaties. Their provisions must be assessed alongside customary law, treaty obligations and state practice. Editors should distinguish visit and search from a declared and effective Naval blockade, although search can enforce blockade and Contraband control.

Peacetime right of approach, flag-state consent, port-state inspection, counter-piracy boarding and action authorised by the Security Council rest on different legal bases. Modern sanctions do not, by themselves, activate belligerent visit and search. Proposals to stop commercial tankers must therefore identify the armed-conflict classification, boarding authority, location, flag-state position and applicable resolution or treaty before invoking this doctrine.

See also

Contraband control · Naval blockade · Prize law and prize courts · San Remo Manual (1994) · Newport Manual on the Law of Naval Warfare (2023)

Sources

1. International Committee of the Red Cross, San Remo Manual, paragraphs 118 to 124 (1994).
2. International Committee of the Red Cross, San Remo Manual, paragraphs 146 to 152 (1994).
3. James Kraska et al., *Newport Manual on the Law of Naval Warfare*, second edition, International Law Studies 105 (2024).
4. United States Department of Defense, *Law of War Manual* (updated July 2023).