(3) Auxiliary coal, repair, supply, or transport ships, as, directly in the service of the belligerent, have an undoubted hostile character.[455]
(4) Knowing coöperation in the transmission of certain messages for the belligerent renders the ship liable to penalty. Such an act as the repetition of signals would fall in this class. Submarine telegraphic cables between a belligerent and a neutral state may become liable to censorship or to interruption beyond neutral jurisdiction if used for hostile purposes. A neutral vessel engaged in the laying, cutting, or repair of war telegraph cables is held to be performing unneutral service.
The general penalty for the performance of unneutral service is the forfeiture of the vessel so engaged.
[§ 134. Visit and Search]
(a) "The right of visiting and searching merchant ships upon the seas—whatever be the ships, whatever be the cargoes, whatever be the destinations—is an incontestable right of the lawfully commissioned cruisers of a belligerent nation,"[456] is the statement of the general principle laid down in the case of the Maria. Judge Story says that the right is "allowed by the general consent of nations in the time of war and limited to those occasions."[457] There is, however, a qualified right of search in the time of peace in case of vessels suspected of piracy or of slave trade. Under these circumstances the right must be exercised with the greatest care, otherwise the searching party is liable to damages.[458]
(b) The Object. In the time of war the right is exercised in order to secure from the neutral the observance of the laws of neutrality, or specifically, according to the regulations of the United States:—
1. To determine the nationality of a vessel.
Note. The right of approach to ascertain the nationality of a vessel is generally allowed in time of peace. "International Law," Naval War College, p. 165.
2. To ascertain whether contraband of war is on board.
3. To ascertain whether a breach of blockade is intended or has been committed.