[544] The four exceptions mentioned in the text above are based on universally recognised customary rules of the Law of Nations. It is, of course, possible for several States to enter into treaty agreements according to which their men-of-war acquire certain powers over each other's merchantmen on the Open Sea. According to such agreements, which are, however, not universal, the following additional exceptions may be enumerated:—
(1) In the interest of the suppression of the slave trade, the signatory Powers of the General Act of the Brussels Conference of 1890 to which all the larger maritime Powers belong, have, by articles 20-65, stipulated that their men-of-war shall have the power, in certain parts of the Open Sea where slave traffic still continues, to stop every suspect vessel under 500 tons.
(2) In the interest of the Fisheries in the North Sea, special cruisers of the littoral Powers control all fishing vessels and bumboats. See below, §§ [282] and [283].
(3) In the interest of Transatlantic telegraph cables, men-of-war of the signatory Powers of the treaty for the protection of such cables have certain powers over merchantmen. (See below, § [287].)
How Verification of Flag is effected.
§ 267. A man-of-war which meets a suspicious merchantman not showing her colours and wishes to verify the same, hoists her own flag and fires a blank cartridge. This is a signal for the other vessel to hoist her flag in reply. If she takes no notice of the signal, the man-of-war fires a shot across her bows. If the suspicious vessel, in spite of this warning, still declines to hoist her flag, the suspicion becomes so grave that the man-of-war may compel her to bring to for the purpose of visiting her and thereby verifying her nationality.
How Visit is effected.
§ 268. The intention to visit may be communicated to a merchantman either by hailing or by the "informing gun"—that is, by firing either one or two blank cartridges. If the vessel takes no notice of this communication, a shot may be fired across her bows as a signal to bring to, and, if this also has no effect, force may be resorted to. After the vessel has been brought to, either an officer is sent on board for the purpose of inspecting her papers, or her master is ordered to bring his ship papers for inspection on board the man-of-war. If the inspection proves the papers to be in order, a memorandum of the visit is made in the log-book, and the vessel is allowed to proceed on her course.
How Search is effected.
§ 269. Search is naturally a measure which visit must always precede. It is because the visit has given no satisfaction that search is instituted. Search is effected by an officer and some of the crew of the man-of-war, the master and crew of the vessel to be searched not being compelled to render any assistance whatever except to open locked cupboards and the like. The search must take place in an orderly way, and no damage must be done to the cargo. If the search proves everything to be in order, the searchers have carefully to replace everything removed, a memorandum of the search is to be made in the log-book, and the searched vessel is to be allowed to proceed on her course.