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  • Natalie Klein (a1), Douglas Guilfoyle (a2), Md Saiful Karim (a3) and Rob McLaughlin (a4)


The ongoing development of diverse maritime autonomous vehicles for varied ocean activities—ranging from scientific research, security surveillance, transportation of goods, military purposes and commission of crimes—is prompting greater consideration of how existing legal frameworks accommodate these vehicles. This article brings together the core legal issues, as well as current developments in relation to commercial shipping, the law of naval warfare, and maritime security. This article captures how these issues are now being addressed and what other legal questions will likely emerge as the newest technology impacts on one of the oldest bodies of international law.



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The research for this article was supported by an Australian Research Council Discovery Project.



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1 DB Larter, ‘5 Things You Should Know about the US Navy's Plans for Autonomous Missile Boats’ (Defence News, 14 January 2020) <>.

2 M Wingrove, ‘Autonomy Tested for Oil Spill Removal’ (Riviera Maritime Media, 7 January 2020) <>.

3 ‘NYK Conducts World's First Maritime Autonomous Surface Ships Trial’ (News Release, 30 September 2019) <>.

4 ‘Detecting Fish from Ocean-Going Robots to Complement Ship-Based Surveys’ (NOAA Fisheries News, 22 August 2019) <>.

5 M Olimpio, ‘Remote Controlled Terror: Houthi Suicide Boats’ (European Eye on Radicalization, 27 September 2018) <>.

6 HI Sutton, ‘Otranto Unmanned-Drug-Vessel’ (Covert Shores blog, 23 June 2019) <>.

7 See discussion in K Bork et al., ‘The Legal Regulation of Floats and Gliders—In Quest of a New Regime?’ (2008) 39 Ocean Development and International Law 298, 308–39; T Hofmann and A Proelss, ‘The Operation of Gliders under the International Law of the Sea (2015) 46 Ocean Development and International Law 167, 177–8.

8 See, eg, McLaughlin, R, Unmanned Naval Vehicles at Sea: USVs, UUVs and the Adequacy of the Law (2011) 21 Journal of Law, Information and Science 100; Schmitt, MN and Goddard, DS, ‘International Law and the Military Use of Unmanned Maritime Systems’ (2016) 98 International Review of the Red Cross 567; Allen, CH, ‘Determining the Legal Status of Unmanned Maritime Vehicles: Formalism vs Functionalism’ (2018) 49 Journal of Maritime Law and Commerce 477.

9 See IMO Maritime Safety Committee, ‘Regulatory Scoping Exercise for the Use of Maritime Autonomous Surface Ships (MASS): Work conducted by the CMI International Working Group on Unmanned Ships’, IMO Doc. MSC 99/INF.8 (13 February 2018); Comité Maritime International, ‘International Working Group Position Paper on Unmanned Ships and the International Regulatory Framework’ (29 March 2017).

10 See, eg, Kraska, J, ‘The Law of Unmanned Naval Systems in War and Peace’ (2010) 5 Journal of Ocean Technology 44; Klein, N, ‘Maritime Autonomous Vehicles within the International Law Framework to Enhance Maritime Security’ (2019) 95 International Law Studies 244.

11 These terms are used interchangeably within the United Nations Convention on the Law of the Sea (UNCLOS) (1982) 1833 UNTS 3. See UN Division for Ocean Affairs and the Law of the Sea, Navigation on the High Seas: Legislative History of Part VII, Section I (Articles 87, 89, 90–94, 96–98) of the United Nations Convention on the Law of the Sea (1989) 80.

12 For example, when referring to the boats of foreign ships that trigger a right of hot pursuit. See UNCLOS, art 111(1). Or when a boat is sent to exercise a right of visit under art 110 of UNCLOS.

13 Where assessing responsibility for pollution of the marine environment. See, eg, UNCLOS, art 194(3) and art 209.

14 Being used for marine scientific research. See, eg, UNCLOS, art 248.

15 Rights of overflight are protected under art 87 of UNCLOS and the use of aircraft for law enforcement is contemplated in arts 110 and 111 of UNCLOS.

16 For discussion, see, eg, E Van Hooydonk, ‘The Law of Unmanned Merchant Shipping – An Exploration’ (2014) 20 Journal of International Maritime Law 403, 406–7.

17 See Allen (n 8) 493.

18 Danish Maritime Authority, ‘Final Report: Analysis of Regulatory Barriers to the Use of Autonomous Ships’, IMO Doc MSC 99/INF.3 (18 January 2018). See also K Chadwick, ‘Unmanned Maritime Systems Will Shape the Future of Naval Operations: Is International Law Ready?’ in MD Evans and S Galani (eds), Maritime Security and the Law of the Sea: Help or Hindrance? (Edward Elgar 2020) 132, 134–5.

19 See IMO Maritime Safety Committee, ‘Regulatory Scoping Exercise for the Use of Maritime Autonomous Surface Ships (MASS): Initial Review of IMO Instruments under the Purview of MSC (Note by the Secretariat)’, IMO Doc MSC 100/INF.3 (9 August 2018). See also Klein (n 10) 249; Chadwick (n 18) 135.

20 A ‘warship’ is ‘manned by a crew which is under regular armed forces discipline’. UNCLOS, art 29.

21 UNCLOS, arts 32, 95 and 96.

22 J Kraska and RP Pedrozo, ‘China's Capture of U.S. Underwater Drone Violates Law of the Sea’ (Lawfare, 16 December 2016) <>. However, arguments that the MAV was a ‘ship’ were not compelling. See MJ Valencia, ‘US-China Underwater Drone Incident: Legal Grey Areas’ (The Diplomat, 11 January 2017) <>.

23 As expected in relation to the right of visit and right of hot pursuit, for example. UNCLOS, arts 110(5) and 111(5).

24 See, eg, Oxford Manual of the Laws of Naval War (1913) <>; L Doswald-Beck et al. (eds), San Remo Manual on International Law Applicable to Armed Conflicts at Sea (Cambridge University Press/IIHL 1995).

25 Geneva Convention (II) for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea, (1949), 75 UNTS 85.

26 An exception is the now decommissioned CAPTOR mine system. ‘The CAPTOR mine is an anti-submarine mine … The name CAPTOR stands for Encapsulated Torpedo. The mine is moored to the sea floor and detects nearby vessels using passive sonar. It is designed to only engage submarines.’ ‘Mark 60 CAPTOR’, <>.

27 AEGIS ‘was designed as a complete system: the missile launching element, the computer programs, the radar and the displays are fully integrated to work together. This makes the Aegis system the first fully integrated combat system built to defend against advanced air and surface threats.’ ‘Naval Sea Systems Command’ (US Navy) <>. CIWS (Close in Weapons System), such as Phalanx, are ‘a self-contained package [that] … automatically carries out functions usually performed by multiple systems: search, detection, threat evaluation, tracking, engagement and kill assessment’. ‘Phalanx Close-In Weapon System’ (Raytheon) <>.

28 ‘US Navy Tests Autonomous Swarm Boats’ (Maritime Executive) <>; K Osborne, ‘The U.S. Navy Is Building a Swarm “Ghost Fleet”’ (The National Interest, 24 January 2019) <>.

29 See, inter alia, J Turner, ‘Sea Hunter: Inside the US Navy's Autonomous Submarine Tracking Vessel’ (Naval Technology, 3 May 2018) <>: ‘Measuring 132ft in length and capable of 27 knots, Sea Hunter is the world's largest unscrewed ship … The [Seahunter's] stated purpose is to locate, track enemy and engage submarines, primarily using a high frequency fixed sonar array, but MCM testing suggests mine countermeasures could be an option.’

30 Hague Convention (VII) of 1907 Relating to the Conversion of Merchant Ships into War-Ships (1907) 205 Consol TS 319, art 1–4.

31 UNCLOS, art 29.

32 Y Dinstein and AW Dahl, Oslo Manual on Select Topics of the Law of Armed Conflict (Springer 2020) rules 52, 56–8.

33 Declaration respecting Maritime Law between Austria, France, Great Britain, Prussia, Russia, Sardinia, and Turkey, signed at Paris, 16 April 1856, British State Papers 1856, vol. LXI, 155–8. On the US position, see C Stockton, ‘The Declaration of Paris’ (1920) 14 AJIL 356, 362–3.

34 J Brown Scott (ed), The Proceedings of the Hague Peace Conferences: The Conference of 1907 (Oxford University Press 1920) Vol III, as argued by, inter alia, the delegations from Mexico at 805–7, and Brazil at 749–52.

35 See, eg, Convention on the International Regulations for Preventing Collisions at Sea (1972), 1050 UNTS 16 (COLREGS), rule 2(a).

36 COLREGS, rule 3(f).

37 Australian Defence Doctrine Publication 00.1: Command and Control (2009) para 1.4, <>.

38 San Remo Manual (n 24) rule 13(h).

39 ibid, rules 65–66 (though noting some exemptions).

40 See, eg, ‘Status of RFA and Requisitioned Merchant Ships’ (Anthony Aust), UK National Archives Document (ALQ 05016), 23 April 1982, in relation to the Falklands conflict, para 4: ‘Only commissioned naval vessels can exercise belligerent rights, eg conduct offensive operations against the enemy. … To be able to exercise belligerent rights a vessel should normally be commissioned into the naval force, be commanded by a commissioned naval officer, fly a naval ensign and be part of its State's military effort at sea.’

41 See, eg, R Tucker, ‘The Law of War and Neutrality at Sea’ (1955) 50 International Law Studies 1, 38–43.

42 See, eg, San Remo Manual (n 24) rule 60.

43 See, eg, ‘Iraqi Mine Smugglers Intercepted by Coalition Forces’ (US Navy, 26 March 2003) <>; ‘26 Iranians Seized with Mine Vessel; More U.S. Shooting’ (New York Times, 23 September 1987) <>.

44 Hague Convention (XIII) of 1907 Concerning the Rights and Duties of Neutral Powers in Naval War (1907) USTS 545, art 10.

45 Hague Convention VIII of 1907 Concerning the Laying of Automatic Submarine Contact Mines (1907) USTS 541, art 1.

46 See, eg, ‘Australia's System of Control and Applications for Autonomous Weapon Systems’, UN Group of Government Experts, UN Doc CCW/GGE.1/2019/WP.2 (26 March 2019) <$file/CCWGGE.12019WP.2Rev.1.pdf>.

47 See, eg, ‘Questionnaire on the Legal Review Mechanisms of New Weapons, Means and Methods of Warfare’, Argentina, UN Doc CCW/GGE.1/2019/WP.6 (29 March 2019) <$file/CCW_GGE.1_2019_WP.6.pdf>.

48 Chadwick comments: ‘There is no doubt that navies will seek to categorise their [MAVs] as warships over and above auxiliaries, military devices or other categories where possible, in order to achieve parity of use with equivalent manned warships.’ Chadwick (n 18) 146.

49 See, eg, Geneva Convention (III) relative to the Treatment of Prisoners of War (1949) 75 UNTS 135, art 4(A)(5).

50 J Brown Scott, ‘The Execution of Captain Fryatt’ (1916) 10 AJIL 865; H Bellot, ‘The Right of a Belligerent Merchantman to Attack’ (1921) 7 Transactions of the Grotius Society 43.

51 See, eg, 1949 Geneva Convention (IV) relative to the Protection of Civilian Persons in Time of War (1949) 75 UNTS 287, [common] art 3; Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Armed Conflicts (Protocol I) (1977) 1125 UNTS 3, art 51(3).

52 IMO, ‘Report of the Maritime Safety Committee on Its Ninety-Eighth Session’, IMO Doc MSC 98/23 (28 June 2017).

53 IMO, ‘Denmark, Estonia, Finland, Japan, the Netherlands, Norway, the Republic of Korea, the United Kingdom and the United States, Maritime Autonomous Surface Ships: Proposal for a regulatory scoping exercise’, IMO Doc MSC 98/20/2 (27 February 2017).

54 Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation, (1988), 1678 UNTS 221 (1988 SUA Convention).

55 IMO, ‘Report of the Legal Committee on the Work of its 105th Session’, IMO Doc LEG 105/14 (1 May 2018).

56 IMO, ‘Report of the Facilitation Committee on its Forty-Third Session’, IMO Doc FAL 43/20 (23 April 2019).

57 IMO, ‘Report of the Marine Environment Protection Committee on its Seventy-Third Session’, IMO Doc MEPC 73/19 (26 October 2018).

58 International Convention for the Safety of Life at Sea (1974) 1184 UNTS 2, (SOLAS).

59 IMO, ‘Initial Review of IMO Instruments under the Purview of MSC: Note by the Secretariat’, IMO Doc MSC 100/INF.3 (9 August 2018).

60 ‘France, Summary of Results of the Second Step of the RSE for SOLAS Chapter II-1’, IMO Doc MSC 102/5/6 (10 February 2020).

61 ‘China, Summary of Results of the Second Step of the RSE for SOLAS Chapter V’, IMO Doc MSC 102/5/9 (11 February 2020).

62 This obligation is not unique to SOLAS, but also enshrined in art 98(1) of UNCLOS and detailed in the Search and Rescue Convention. International Convention on Maritime Search and Rescue (1979) 1405 UNTS 97.

63 UNCLOS, art 94(4)(b) and art 94(4)(c); the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW) (1978), 1361 UNTS 2; SOLAS, Chapter V, regulation 14.

64 SOLAS, Chapter V, regulation 14(1).

65 IMO, ‘Report of the Maritime Safety Committee on its One Hundredth Session’, IMO Doc MSC 100/20/Add.1 (12 December 2018).

66 ibid.

67 IMO, ‘Belgium, China and the Netherlands, Summary of Results of the Second Step of the RSE for SOLAS Chapter III and the LSA Code’, IMO Doc. MSC 102/5/4 (10 February 2020).

68 MS Karim, Prevention of Pollution of the Marine Environment from Vessels: The Potential and Limits of the International Maritime Organisation (Springer 2015) 8.

69 Danish Maritime Authority (n 18) 29.

70 ibid.

71 C Bueger, ‘What is Maritime Security?’ (2015) 53 Marine Policy 159, 159–60; N Klein, Maritime Security and the Law of the Sea (Oxford University Press 2011) 11.

72 UN General Assembly Annual Resolution on Oceans and the Law of the Sea, UN Doc A/RES/74/19 (20 December 2019), preamble and paras 154 and 196(b).

73 See T Abke, ‘Indo-Pacific Countries Turn to Unmanned Vessels to Patrol Region's Waters’ (Indo-Pacific Defence Forum, 25 January 2019) <>.

74 See further Klein (n 10) 266–70; and more generally D Guilfoyle, ‘Maritime Law Enforcement Operations and Intelligence in an Age of Maritime Security’ (2017) 93 International Law Studies 298.

75 UNCLOS, art 220(2).

76 UNCLOS, art 220(6).

77 UNCLOS, art 73(1).

78 UNCLOS, art 111(1).

79 UNCLOS, art 111(4) and (5).

80 See further Klein (n 10) 254.

81 See above Section III.A.

82 See further Allen (n 8) 507; and Section V.B below.

83 UNCLOS, art 111(6)(b).

84 For discussion on multinational pursuit cases see Gullett, W and Schofield, C, ‘Pushing the limits of the Law of the Sea Convention: Australian and French cooperative surveillance and enforcement in the Southern Ocean’ (2007) 22 International Journal of Marine and Coastal Law 545, 569.

85 Guilfoyle, D, Shipping Interdiction and the Law of the Sea (Cambridge University Press 2009) 271; citing I'm Alone (1935) 3 RIAA 1609; Red Crusader (1962) 35 ILR 485; MV Saiga (No 2) (Saint Vincent and the Grenadines v Guinea), ITLOS Case No 2; (1999) 38 ILM 1323.

86 See O'Connell, ME, ‘Seductive Drones: Learning from a Decade of Lethal Operations’ (2012) 21(2) Journal of Law, Information and Science 116.

87 Guilfoyle (n 84) 4; see further Papastavridis, E, The Interception of Vessels on the High Seas: Contemporary Challenges to the Legal Order of the Oceans (Hart Publishing 2013) 5060.

88 UNCLOS, art 110.

89 Klein (n 10) 257.

90 Schmitt, MN (ed), Tallinn Manual 2.0 on the International Law Applicable to Cyber Operations (Cambridge University Press 2017) 238 (rule 46, para 10).

91 UNCLOS, art 100.

92 The 2005 Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation combines the 1998 SUA Convention and a 2005 Protocol (2005 SUA Protocol). Protocol of 2005 to the Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation (2006) IMO Doc leg/conf.15/21.

93 ‘Narco-subs, Cartels and Law Enforcement’ (Foreign Brief, 9 May 2016) <>.

94 SUA Convention, art 3. See also MS Karim, Maritime Terrorism and the Role of Judicial Institutions in the International Legal Order (Brill Nijhoff 2017) 55.

95 2005 SUA Protocol, art 3bis. See also Karim (n 94) 60.

96 1988 SUA Convention, arts 6, 7 and 8. See Karim (n 94) 72–3.

97 IMO, ‘United States of America, Summary of Results of the LEG Regulatory Scoping Exercise for the Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation’, 1988, IMO Doc LEG 107/8/5 (9 January 2020).

98 Comité Maritime International (CMI), ‘Summary of Results of Analysis of IMO Instruments under the Purview of the Legal Committee’, IMO Doc LEG 107/8 (13 December 2019).

The research for this article was supported by an Australian Research Council Discovery Project.



  • Natalie Klein (a1), Douglas Guilfoyle (a2), Md Saiful Karim (a3) and Rob McLaughlin (a4)


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