 The term `laws of armed con#icta is used to describe both the `Haguea laws of war, and the `Genevaa laws concerning the victims of war.  `Unit self-defencea is an extension of the inherent right of self- defence embodied in Article 51 of the UN Charter. Detailed commen- tary on this topic is provided in the Case Concerning Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States), 1986 ICJ Reports at 14.  For further comment, particularly regarding the distinction be- tween self-defence and aggression, see [3].  The views expressed in this article are those of the author and should not be considered as the policy of either the Royal Australian Navy or the Australian Defence Force. * Corresponding author. Tel.: # 61-2-6265-1657; fax: # 61-2-6265- 1239. E-mail address: david.letts@cbr.defence.gov.au (D.J. Letts).  The Australian Defence Force (ADF) is comprised of three arms * the Royal Australian Navy (`the RANa), Australian Army (`the Armya) and Royal Australian Air Force (`the RAAFa).  Recent statements by both the Australian government and the federal opposition have stressed the importance of a Navy that is equipped to perform a variety of roles outside those typically associated with Naval warfare: ASP (1997) and Australian Labor Party Defence Policy statement at www.alp.org.au/. A contemporary analysis of the need for a review of the RAN's force structure is provided by A.W. Grazebrook [2]. Marine Policy 24 (2000) 149}157 The use of force in patrolling Australia's "shing zones  David J. Letts* Defence Legal Ozce, R8-2-012, Russell Ozces, Canberra, ACT 2600, Australia Received 1 June 1999; accepted 1 August 1999 Abstract The Royal Australian Navy has been conducting "shery patrols for many years. Part of the rationale for the RAN's involvement in these operations is that the use of armed force may prove necessary if a vessel refuses to comply with directions given by the commanding o$cer of an RAN vessel. This paper examines the legality of using such force, and "nds that the RAN is operating with inadequate municipal legal support and questionable international legal authority.  2000 Elsevier Science Ltd. All rights reserved. Keywords: Use of force; Fisheries surveillance; Naval operations 1. Introduction The political, legal and strategic environment in which the Royal Australian Navy (RAN) operates is in#uenced by a wide variety of factors. The release of Australia's Strategic Policy [1] by the Minister for Defence in De- cember 1997 signi"es the most recent version of a series of policy papers and similar publications that have at- tempted to analyse this environment and de"ne the roles that are assigned to the Australian Defence Force (ADF).  Within this context, the role of the RAN in helping to achieve Australia's strategic policy objectives is signi"cant. In particular, the variety of tasks that the RAN is now expected to ful"l includes many tasks that would prove very di$cult without the current, balanced Naval force that comprises the RAN. One of the inevitable consequences associated with tasking the RAN to conduct operations is that there must be an accompanying willingness on the part of political and Naval commanders to authorise the use of force by the RAN in appropriate circumstances. The di$culty lies in de"ning precisely what `appropriate circumstancesa actually constitute, particularly in periods where the laws of armed con#ict do not apply. In peacetime, the ability of an individual commanding o$cer to invoke unilateral use of force is limited by constraints imposed by higher authority for each particular operation or exercise. The commanding o$cer will then further specify the limita- tions that are placed on the use of any of the vessel's onboard weapons systems. However, the complexity of the situation is exacerbated if one considers the well- established argument that an individual commanding o$cer has the right to use force without recourse to any speci"c instruction as an exercise of the right of `unit self-defencea.  Additionally, this right of self-defence exists in both peacetime and during periods of con#ict, and while an individual may choose not to exercise the right, it is nevertheless considered a non-derogable right. There are a number of peacetime roles assigned to the RAN where the use of force has been, or may prove 0308-597X/00/$ - see front matter  2000 Elsevier Science Ltd. All rights reserved. PII: S 0 3 0 8 - 5 9 7 X ( 9 9 ) 0 0 0 2 6 - 3