Year Ahead – The Legal Status of Unmanned Maritime (Naval) Systems: A Never-Ending Story?

by | Jan 5, 2023

Unmanned Maritime Systems

An international workshop held at the U.S. Naval War College in Newport, R.I., from 20 to 21 March 2012, was to discuss the legal status of unmanned maritime systems (UMS) operated by the regular armed forces.[i] The result was not necessarily conclusive. Since then, many scholars and government experts have exerted considerable efforts in determining the legal status of such systems.

The issues at stake seem to be complex, and State practice is inconclusive. Of course, if regular armed forces operate UMS for exclusively governmental non-commercial purposes, they enjoy sovereign immunity (a State property) and, arguably, all navigational rights. However, for the purposes of the jus in bello, in particular the law of naval warfare, determining the legal status of UMS is crucial.

It may be recalled that the exercise of belligerent rights at sea, which include attacks and prize measures, is strictly limited to warships as defined in Article 29 of the 1982 UN Convention on the Law of the Sea, which is reflective of customary law. If UMS cannot be classified as warships, they might not be employed in times of armed conflict for the exercise of belligerent rights, if they are not an integral component of a surface or subsurface platform. The on-going discussions on an update of the San Remo Manual on International Law Applicable to Armed Conflicts at Sea have revealed a remarkable opposition to their classification as warships.

It is not to be expected that the problem will be solved in the course of further academic discussions. Today, many navies operate UMS for a variety of purposes. Therefore, the time is ripe to rule off the discussion and to have UMS included in the national registries of warships. Such inclusion will then qualify as State practice that will eventually result in the classification of UMS as warships under customary international law.


Wolff Heintschel von Heinegg holds the Chair of Public Law, in particular Public International law, European Law and Foreign Constitutional Law at the Europa-Universität Viadrina in Frankfurt (Oder), Germany.


Photo credit: U.S. Navy Chief Mass Communication Specialist Shannon Renfroe

[i] See Andrew Norris, ‘Legal Status Relating to Unmanned Maritime Systems’, U.S. Naval War College (2013), available at: