In the absence of an international consensus, a coherent argument is that UNCLOS regulates how states deal with their vessels, but allows the question of what constitutes a ship to be determined by national laws. This is supported by Article 91 which provides that “Every State shall fix the conditions for the grant of its nationality to ships, for the registration of ships in its territory, and for the right to fly its flag”. At a national level, the definition of a ship is mostly unconnected to manning requirements. Under English law, the term ship “includes every description of vessel used in navigation”, and even though navigation is undefined and it is unclear whether manning is its prerequisite, it is expected that unmanned vessels will satisfy the definition.
Assuming that unmanned vessels are ‘ships’ within the meaning of UNCLOS, they will be subject to the same obligations that apply to manned vessels and their flag states. The duties of the flag state are outlined in Article 94, effectively leaving such measures to the discretion of each state, by referring to an abstract set of “generally accepted international regulations, procedures and practices” that the measures must conform to. In this way, UNCLOS preserves its relevance in times of shifting practices in the maritime industry.
The discretion given by UNCLOS to each state could have a problematic effect when it comes to the navigational rights of unmanned ships. A ship is subject to the laws of her flag state, based on her nationality, but also to the laws of coastal or port states, according to her physical location at any given point. Potentially, this could have the consequence of an unmanned vessel constituting a ship under the flag state’s law, but not under the law of the coastal or port state.
The flag state’s jurisdiction applies at all times, irrespective of the vessel’s location, whereas the parallel jurisdiction of coastal or port states increases with the proximity of the vessel to its shores. As follows, if the vessel is present in the ports or internal waters, the coastal state has broad jurisdiction over her and a wide discretion when it comes to entry conditions for foreign ships, by virtue of Article 25 UNCLOS. Theoretically, a coastal or port state could decline access to its ports or internal waters by unmanned vessels, as long as the refusal is reasonable, non-discriminatory and proportional. Further limiting the coastal state’s right, Article 300 provides that states “shall exercise the rights, jurisdiction and freedoms recognised in this Convention in a manner which would not constitute an abuse of right”.
When the vessel is passing through a state’s territorial sea, their rights and jurisdiction are more limited. By virtue of a well-established principle of the law of the sea, all ships have a right of ‘innocent passage’ through territorial waters of other states. Passage is deemed innocent “so long as it is not prejudicial to the peace, good order or security of the coastal State”. Since passage of an unmanned ship would not be more prejudicial than that of a manned one, it seems that unmanned vessels will be mostly protected in territorial waters and allowed to pass through, as long as their activities do not fall within Article 19(2) UNCLOS.