The use of submarines in naval operations is legitimate provided that in dealing with merchant ships they conform to the rules to which surface vessels are subject. In particular, except in the case of persistent refusal to stop on being duly summoned, or of forcible resistance to visit or search, a submarine may not attack or render incapable of navigation a merchant vessel without having first placed passengers, crew and the ship’s papers in place of safety. For this purpose the ship’s boats are not regarded as a place of safety unless the safety of the passengers and crew is assured, in the existing sea and weather conditions, by the proximity of land, or the presence of another vessel which is in a position to take on board.
In a territorial sea, straits or canals, submarines are required to navigate on the surface and to show their flag.
See also Naval warfare;





Suggested readings:
MIDDLETON Drew, Submarine, The Ultimate Naval Weapon, Chicago, Playboy Press, 1976, 256 pp.
PARKS William H., “Making Law of War Treaties: Lessons for Submarine Warfare Regulation”, in SCHMITT Michael N. (ed.), International Law across the Spectrum of Conflict, Newport, R.I., 2000, pp. 339-385.
WEISS C.J., “Problems of Submarine Warfare under International Law”, in Intramural Law Review, Vol. 22, 1967, pp. 136-151.
Further readings:
GILLILAND Jane, “Submarines and Targets: Suggestions for New Codified Rules of Submarine Warfare”, in Georgetown Law Journal, No. 3, 1985, pp. 975-1005.
KERR Alex A., “International Law and the Future of Submarine Warfare”, in United States Naval Institute Proceedings, Vol. 81, 1955, pp. 1105-1110.