4.4 Coastal state jurisdiction
As opposed to flag states, coastal states are under no obligation in UNCLOS to implement maritime safety or environmental rules, but only have a right to do so. That right is significantly circumscribed by ships’ navigational rights in the territorial sea, notably for rules relating to "the design, construction, manning and equipment of foreign ships"(1) UNCLOS article 21(2) and in the EEZ.(2) UNCLOS article 211(5)
However, in view of the international origin and widespread acceptance of the rules in question here, the jurisdiction of states to require compliance by foreign ships with the relevant fuel quality requirements in their coastal waters (including EEZ) is not in doubt. It is widely acknowledged that the fuel quality requirements of Marpol Annex VI, including those applying only in SECAs, meet the requirement of 'general acceptance',(3) See note 31 above. and hence lie within the scope of coastal states' prescriptive jurisdiction.
The real limitations for coastal states lie in the realm of enforcement. States' rights to exercise enforcement jurisdiction over foreign ships that merely transit their waters is heavily circumscribed in UNCLOS in all sea areas except their internal waters. In the territorial sea, the coastal state may, if it has ‘clear grounds for believing’ that a ship navigating in the territorial sea has violated the rules, physically inspect the ship, which includes the right to stop the vessel and board it, and possibly the right to order it to port. The action must, however, be without prejudice to the application of the provisions of UNCLOS Part II on innocent passage. In the EEZ, enforcement is limited to cases where the pollution has already taken place and varies with the severity of the damage caused or likely to be caused. Jurisdiction for at-sea enforcement measures with respect to air emissions will generally be limited to certain basic information requests under article 220(3). Physical inspection under article 220(5) will normally be ruled out, as the air emission by an individual ship is unlikely to meet the requirement of ‘substantial discharge’ and ‘significant pollution’.
In view of such legal constraints, and a number of more practical reasons,(4) In-port enforcement represents a lesser interference with navigation and is also safer, less costly and more practical from the point of view of authorities. This is particularly the case as regards air emissions, as verification usually requires samples to be taken from the ship’s fuels tanks and pipes for a subsequent detailed analysis of those samples by a laboratory. it is assumed that the rules will mainly be enforced by port states with respect to ships that are voluntarily in their ports. The further analysis thus focuses on the rights of port states to take measures against non-complying ships.