Sometimes local notification is made to port and consular authorities of the place blockaded.
In recent years the time allowed a vessel to discharge, reload, and to leave port has been specified.
In case of special notification by the officer in command of a blockading ship, the fact with particulars should be entered in the log of the neutral vessel over the officer's signature.
(f) A Blockade must be Effective. This principle applies both to the place and to the manner of enforcement.
1. It must apply to a place which may be blockaded, i.e. to seaports, rivers, gulfs, bays, roadsteads, etc. A river which forms the boundary between one of the belligerent states and a neutral state may not be blockaded. Rivers flowing for a part of their course through belligerent territory but discharging through neutral territory may not be blockaded. Certain waters are not liable to blockade because exempt by agreement; as in the case of the Congo River by the Act of 1885.
2. "Blockades, in order to be binding, must be effective, that is to say, maintained by a force sufficient really to prevent access to the coast of the enemy."[471] This is interpreted in the United States Naval Code as a "force sufficient to render hazardous the ingress to or egress from a port."[472] The subject of the degree of effectiveness which is necessary has been much discussed, and can only be determined by the circumstances in a given case.[473] The English interpretation in the main agrees with that of the United States. The Continental states are inclined to give a more literal interpretation to the rule.
(g) Cessation. A blockade comes to an end:—
- 1. By the cessation of any attempt to render it effective.
- 2. By the repulse by force of the vessels attempting to maintain the blockade.
- 3. For a given neutral vessel when there is no evidence of a blockade, after due care to respect its existence. This may happen when the blockading force is absent in pursuit of an offending vessel, or for similar reason.
In this last case the Continental authorities hold that the neutral is free to enter without question, as it is the duty of the belligerent to render the blockade at all times evident and effective. The English and American authorities generally consider such a case merely an interruption, and hold that it does not require that the blockade be proclaimed again. There is a general agreement that in the other cases it must be formally instituted again as it was in the beginning.