As a general rule, foreign ships enjoy no automatic right of access to ports of other nations, except in times of distress when lives are at stake or when another treaty is applicable. States have the right to exclude foreign vessels from their ports and inland waterways, and may apply national laws and regulations to foreign ships when at port.
As a result, the port state has concurrent jurisdiction with the flag state when a ship is at port. Port state efforts to regulate foreign-flagged ships are subject to certain limits. Any regulation must not be an abuse of rights, it must not seek to exercise jurisdiction over matters considered the “internal economy” of the ship, it cannot hamper “innocent passage” and it must not have the practical effect of impacting the “construction, design, equipment or manning (CDEM)” of ships (Art 21(2) UNCLOS).
(ICCT, Air Pollution and GHG Emissions from Ocean-going Ships: Impacts, Mitigation Options and Opportunities for Managing Growth, March 2007)
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