Tac Talks: Taking the first hit? Time to revisit unit self-defence as an inherent right

Tac Talks No. 42
Tac Talks No. 42

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CAPT Stu Waters
Soldiers from the 7th Battalion, Royal Australian Regiment Task Group (7 RAR TG) Other Government Agency Platoon Two interact with locals in Tarin Kot, Uruzgan, Afghanistan. Photographer: CAPT Jesse Platz.
Soldiers from the 7th Battalion, Royal Australian Regiment Task Group (7 RAR TG) Other Government Agency Platoon Two interact with locals in Tarin Kot, Uruzgan, Afghanistan. Photographer: CAPT Jesse Platz.

Uruzgan, Afghanistan 2010: An Australian corporal is on patrol. He had received an intelligence briefing about a vehicle-borne threat in the area at the pre-patrol briefing, with a detailed description of the threat truck. A vehicle meeting the description approaches at high speed, manoeuvring aggressively and engages the soldier with rifle fire before turning away. Remaining within visual range, it then turns back at speed towards the corporal, who has no cover. Weapons visible are visible from the truck and it quickly approaches firing range. Can the corporal engage with his weapon?

Gulf of Oman 2015: An Australian frigate is operating off the coast of Yemen on an international maritime security mission. Intelligence has been received that rebel forces were intent on engaging coalition warships in the area, using former Yemeni Air Force (YAF) aircraft and their missiles. The frigate detects an aircraft - electronic warfare indicates that the jet is ex-YAF. It targets the Australian frigate with its fire control radar and launches a first missile, which fails to lock on to the ship and passes safely astern. It turns back for another run on a weapon release profile. Fire control radar is detected and the jet nears missile launch range - there is no response to warnings on Guard. Can the frigate Commanding Officer engage?

HMAS Toowoomba, right, turns away from US Naval Ship Supply on the completion of replenishment at sea while patrolling the Gulf of Oman during tasking with the International Maritime Security Construct. Photographer: LSIS Richard Cordell.
HMAS Toowoomba, right, turns away from US Naval Ship Supply on the completion of replenishment at sea while patrolling the Gulf of Oman during tasking with the International Maritime Security Construct. Photographer: LSIS Richard Cordell.

On the face of it, these two hypothetical tactical situations appear to be very similar. In both cases, intelligence provides information regarding the capability, intent and preparedness of an adversary to inflict potentially lethal damage. This intelligence is quickly manifested by an initial unsuccessful engagement by the adversary. Faced with the second and now immediate threat the corporal and CO are faced with the same question - can I shoot?

The answer, remarkably given the similar threat circumstances, is very different. The corporal has the inherent right of individual self-defence and can engage regardless of his Rules of Engagement (ROE), provided there is an imminent threat to life. For the frigate Commanding Officer, the story is very different - his ability to engage depends on several factors. He has the right to exercise unit self-defence, but in the Australian context, this might be cancelled or modified by his issued ROE. Due to Australian policy, there is a very real possibility of a navy warship being forced to take the first hit, with catastrophic consequences. Notably, if the ship and its CO belonged to a different country, the ROE would be irrelevant - in many other navies the right of unit self-defence is considered inherent and the commander would be able to engage, provided the very strict criteria that limit unit self-defence were evident.

As the United States Army chief, General Ray Odierno stated in November 2014, the “velocity of instability” is growing. Conflict in the Middle East stretches from Yemen to Syria, while tensions in the Asia-Pacific are rising. The risk of Australian naval forces being involved in a conflict is growing. Those Australian forces who are sent in harm’s way must be provided with the tools with which to protect themselves when faced with an imminent and manifest threat to life and unit. Noting current trends in the lethality of emerging technologies, ‘taking the first hit’ and surviving is no longer a feasible option.

This essay will explore why the rights of the two hypothetical tactical actors are so different in such similar operational conditions. It will look at the legal roots of unit self-defence and consider why many legal scholars and states consider it to be an inherent right, in stark contrast to the Australian policy position. This essay concludes that, given these legal origins in customary international law, the opinion that unit self-defence is an inherent right is ultimately persuasive and recommends that the Australian position is urgently reviewed.

Australian Policy on Self-Defence


The RAN Manual of International Law states that unit self-defence is non-derogable - that is to say that it cannot be temporarily suspended or subject to conditions. Examples of non-derogable rights include the right to life under Article 6 of the International Covenant on Civil and Political Rights. There is an important distinction between non-derogable rights and absolute rights - some non-derogable rights provide for limitations in their ordinary application. For example, the right to life is expressed as freedom from ‘arbitrary’ deprivation of life - providing for circumstances that may justify the taking of life was necessary, reasonable and proportionate.

Australian doctrine provides a more restrictive view. ADDP 06.1 starts with an explanation that self-defence is an inherent right, but immediately qualifies this by stating that it ‘allows individuals to defend themselves against hostile acts and demonstrations of hostile intent.’ It states that self-defence is also an inherent right for nations. According to ADDP 06.1 unit self-defence is quite explicitly not an inherent right. It does state that unit self-defence exists unless otherwise modified. This is more than an academic distinction - it means that unit self-defence may be modified by ROE or direction from a superior commander and that defence of non-ADF units must be specifically authorised in the ROE.

Japan Maritime Self-Defense Force destroyer JS Makinami launches an Evolved Sea Sparrow Missile during Exercise PACIFIC VANGUARD in the East Australian Exercise Area. Photographer: LSIS Daniel Goodman.
Japan Maritime Self-Defense Force destroyer JS Makinami launches an Evolved Sea Sparrow Missile during Exercise PACIFIC VANGUARD in the East Australian Exercise Area. Photographer: LSIS Daniel Goodman.

The result is twofold: it means that a Commanding Officer under fire must know exactly what limits his ROE places on his ability to exercise force in-unit self-defence. Secondly, it conflates the concepts of ROE and self-defence. The inclusion of self-defence as regulated by ROE has been a hot topic amongst legal academics worldwide - Ivan Shearer suggests that the, “in principle, self-defence can never be regulated by extraneous instructions… but that in practice it may be”. Mark Maxwell has argued that there must be a clear distinction between rules regarding the force able to be used for mission accomplishment and rules set forth the right to use force for individual self-defence. This includes situations where ROE may have specified that certain weapon systems are not activated which may limit a warship’s capacity for self-defence - according to Shearer there is also scope for a CO to become so “ROE-minded as to delay responsive action when confronted with a situation threatening the survival of the ship”. Dale Stephens argues that the right of unit self-defence applies independently of determining applicable ROE. There is a strong case to remove any mention of self-defence from ROE - to include it only conflates two very different concepts.

In my experience as a PWO Instructor, it was difficult to manufacture a sufficiently threatening situation that would convince a PWO student or Air Warfare Adqual student that they needed to act in self-defence and defend their ship. The default response always seemed to be: take the first hit and request ROE upgrades to respond.

National and Individual Self-Defence in International Law: The UN Charter


Unlike Australian domestic law where laws are passed by parliament, international law has no global legislature. Consequently, it is often referred to as a horizontal rather than vertical legal system. International law, dealing with the relations of nations with each other, is derived principally from treaties, customary law, and the (very few) general principles of law recognised by civilised nations. Finally, and as a subsidiary means for the determination of international law, by judicial decisions and teaching of eminent legal scholars. These principles are articulated in the RAN Manual of International Law. Due to the range of sources, the formation of international law occurs through continuous development by claim and counter-claim. Its development has been characterised by MacDougall as:

…a process of continuous interaction, of continuous demand and response, in which the decision-makers of particular nation-states unilaterally put forward claims of the most diverse and conflicting character [...] and in which other decision-makers [...] weigh and appraise these competing claims in terms of the interests of the world community and of the rival claimant, and ultimately accept or reject them.

The most prominent source of international law relating to self-defence is the Charter of the United Nations which effectively constitutes international law made by treaty. Article 2(4) of the UN Charter prohibits all Members of the UN in the conduct of their international relations from the use or threat of use of force against the territorial integrity or political independence of any state or in any other matter inconsistent with the purposes of the UN. There are two exceptions - actions under national or collective self-defence under Article 51 or for collective action further to Security Council direction under Article 42. Importantly, Article 51 refers explicitly to the inherent rights of individual and national self-defence, establishing the basis for individual self-defence exercised by our hypothetical corporal in Uruzgan.

What about unit self-defence?


The UN Charter is silent on unit self-defence. According to the RAN Manual of International Law, the CO of a warship has the right to act in-unit self-defence to protect both his vessel and any other vessel under his command. Importantly, the manual explains that this exists in customary international law and carries with it “an absolute through narrow discretion”. This is arguably contrary to the Australian doctrine on the subject. Notably, the US military regards unit self-defence as both a right and an obligation, which is an important consideration when working in a coalition environment.

There is ample international legal scholarship to suggest that unit self-defence is an inherent right including Ivan Shearer, Charles Trumbull and Mark Maxwell. Dale Stephens considers that individual self-defence is a subset of unit self-defence, suggesting that it too is an inherent right. He also states that it is not a right dependent upon Article 51 or that derives from the law of armed conflict, but is a “legal right which stands alone and possesses its indigenous authority”. The legal scholar Boddens-Hosang is more explicit, stating that the right to unit self-defence is inherent and applies regardless of ROE. Dale Stephens identifies three predominant characteristics of unit-self-defence which are important in determining its character as an inherent right:

  1. It applies only to a State’s military forces.
  2. It is a customary right that attaches to the unit as an organic whole - including international task forces acting as a single unit.
  3. The temporal limits on when force may be applied are set by the principles in the Caroline case, to which we will now turn our attention.

The Caroline Case


The view that unit self-defence is an expression of customary international law is often linked to the Caroline case. On the night of 29-30 December 1837, a British warship entered US territory and destroyed an American steamboat named the Caroline. The British argued the vessel was being used by Canadian rebels to expel the British from Canada. The British government had sought American government assistance to stop the supply of arms and personnel, but there was no formal action by the US government. The British naval officer Captain Andrew Drew pursued the vessel across the border from Canada, seized it, set it alight and destroyed it by sending it over the Niagara Falls. The attack resulted in the death of two US nationals, provoking an angry diplomatic exchange.

The Caroline incident was an early example of an attempt to restrict the right to go to war to cases of direct and immediate danger. On 6 February 1838, the British Ambassador in Washington Fox wrote to the American Secretary of State seeking to justify the action, stating that “…the piratical character of the steamship Caroline and the necessity of self-defence and self-preservation, under which Her Majesty’s subjects acted in destroying the vessel, would seem to be sufficiently established”. Correspondence on 24 April 1841 from the American Secretary of State Webster, required the British Government to show the existence of:

... the necessity of self-defence, instant, overwhelming, leaving no choice of means, and no moment for deliberation. It will be for it to show, also, that the local authorities of Canada, even supposing the necessity of the moment authorised them to enter the territories of the United States at all, did nothing unreasonable or excessive; since the act justified by the necessity of self-defence, must be limited by that necessity, and kept clearly within it.

The exchange of correspondence codified the right of individual self-defence and has emerged as a foundation of customary international law - Webster’s words have become ingrained in the annals of international law as representing the limits of unit self-defence. According to Dale Stephens, “the enduring legacy of the Caroline exchange is the enunciation of principles which continue to influence the law relating to unit self-defence to this day, having established the twin requirements for necessity and proportionality”.

Unit Self-Defence - Hostile Act and Hostile Intent


The right to self-defence is described as non-derogable. As the RAN Manual of Law states, “reflecting the principle of ‘necessity as traditionally understood in international law, actions premised upon the right of unit self-defence may only be undertaken in response to the commission of a hostile act or demonstration of hostile intent”. These terms are not defined in the UN Charter because the right of unit self-defence is a discrete rule that exists within customary international law. The RAN manual states that hostile act is defined as the actual use of armed force and hostile intent is established when an adversary manifests a threat of imminent use of force.

Boddens-Hosang provides a similar analysis, citing his participation in the deliberations of the NATO Military Committee working group on ROE. In the views of some nations, self-defence was strictly related to the Caroline criteria of imminence and was justified in response to an imminent or actual attack. The hostile act was considered a larger category which included attacks, but broader military acts of a more political nature were relevant to national self-defence but not necessarily unit self-defence. He suggests that imminence is the key criteria here, opening a category for hostile attacks other than actual attacks. Importantly, the use of force in response to these actions must be based on ROE authorisation rather than unit self-defence. Guy Phillips posits that the interface between law, operations and available intelligence is significant in determining the existence of hostile intent. The requirements of ‘instant necessity’ in the Caroline principle mean that the decision to use force in self-defence will be critical and time-sensitive. The RAN Manual suggests that the decision will be based on the opposition capability and preparedness to inflict damage, including intelligence, but also provides some objective indicators that have been developed over time including:

  1. an opposing unit manoeuvring into a weapon launch profile,
  2. presence of a third party to coordinate over the horizon targeting,
  3. locking on of fire control radars, the opening of bomb bay doors,
  4. acoustic detection of torpedo or missile tube doors,
  5. hostile ECM,
  6. distance, speed and bearing of an opposing unit or force.

These are relevant criteria that, along with the prevailing political circumstances, must be incorporated into the decision-making process - the bottom line in the RAN Manual of International Law is the key phrase that “a CO does not need to take the first hit before he or she can respond in-unit self-defence”. This appears unrealistic, especially in the age of hypersonic anti-shipping missiles, but is also inconsistent with Australian doctrine. As Shearer states:

As each new generation of weapons comes along, as modifications to such weapons are made, and sensory devices and defensive systems are developed and extended, the indicia of the hostile intent act require definition and re-definition. These definitions lie at the heart of ROE for they illuminate the murky borderland between hostile intent and hostile act to pinpoint factors that will mark the translation point of one to the other, justifying measures of self-defence by a pre-emptive attack.

It is worth noting that the indicia outlined above may well be similar to those being used by the adversary force in the tense period immediately before hostilities occurring. This has been demonstrated in historical examples where the outward appearance of a ship’s battle readiness and manoeuvres can hold legal ramifications, as illustrated by the Corfu Channel Case.

The issue of waiting for an imminent ‘armed attack’ as strictly interpreted by some academics is an extremely conservative application of the Caroline principles and does not take into account the tactical reality of modern naval weaponry. As Professor O’Connell stated:

Technology has made of this a potentially lethal game, for weapon systems are so instantly activated, and homing or guidance systems, are, in theory in at least, so accurate and their terminal impact is so destructive, and the design of warships affords so little possibility for damage control, that the victim may well be deprived of the capacity of self-defence.

The relevant test in modern circumstances, is therefore on of reasonableness, taking into account the information reasonably available at the time.

Unit Self-Defence vs Individual Self-Defence


The scholar Boddens-Hosang analysed the source of unit self-defence and concluded that linking it with national self-defence is problematic. He proposes that an alternative approach is to view the unit as a collection of individuals. Unit self-defence is therefore a collective exercise of individual self-defence. He ultimately concludes that this approach is similarly flawed because the interpretations related to individual self-defence in national criminal systems differ considerably, making it an “unstable basis for combined military action”. Unit self-defence is fundamentally linked to the military nature of the unit, and the legal basis must be applicable in military activities.

A third option is the right of unit self-defence originating from a non-derogable human right based on the right to life as found in the International Covenant on Civil and Political Rights. Boddens-Hosang finds this theory equally untenable - the right to life is not absolute even under this covenant. It is a prohibition on the arbitrary deprivation of life. Lawful actions that result in death - such as the use of force by combatants in armed conflict are not a violation of this right to life.

National or Individual? Or neither?


Boddens-Hosang ultimately concludes that the right of unit self-defence can best be described as a tactical level application of national self-defence (admittedly without the same consequences or associated legal criteria). This is supported by Dinstein who proposes that self-defence is always exercised by the state - the actions of the lowest ranking soldier are attributed to the state they serve. By contrast, Charles Trumbull rejects this argument noting the concept does not fit comfortably within the national framework under Article 51 - for example, States are required to report all actions taken in national self-defence to the UN Security Council. As he observes, the San Remo Handbook on Rules of Engagement, drafted by experts from a range of states, recognises the distinction between unit and national self-defence. As a further example, the test of immediacy is substantially different between the unit and national self-defence - the US did not respond to the September 11 attacks on the World Trade Centre and Pentagon until 7 October. Consider a situation that might involve violations of territorial airspace and waters by units of the armed forces of a State. If undetected or unopposed there may not be any actual use of force. While there may be a violation of sovereignty, there may not be sufficient to invoke the operation of Article 2(4) and would fail to make the threshold for unit self-defence.

The Nicaragua Case - the International Court of Justice and Self-Defence


To further complicate matters, the International Court of Justice interpreted several elements relating to the use of force in self-defence in the Nicaragua case. The case considered US actions providing support to rebels seeking to overthrow the government of Nicaragua. The right of national self-defence in response to an armed attack is established by Article 51 - the ICJ found that this necessitated a requisite degree of gravity and specifically refused to comment on anticipatory self-defence. The ICJ relied on Article 51 in finding that self-defence could only be justified in response to the armed attack but defined this narrowly - it went on to state that action was warranted in response to attacks of certain ‘scale and effects’ only - attacks failing to meet this threshold were characterised as ‘frontier incidents’ and could not justify self-defence.

Dale Stephens regards this as concerning because the Court fails to have recognised the tactical significance of unit self-defence which would be required in circumstances that might be considered as falling short of the threshold and therefore characterised as a ‘frontier incident.’ After considering the reasoning of the Nicaragua case Stephens concludes that it is fallacious to limit unit self-defence to the Article 51 framework given that this would effectively negate the application of the principle. Similarly, Trumbull contends that differentiating between national and unit self-defence helps overcome the inconsistencies in the Nicaragua case. As he contends, it is widely accepted that the soldier under fire whether in an armed attack or a ‘frontier incident’, has the right to defend him or herself. Despite a range of viewpoints, it is reasonably clear that the Nicaragua decision does not limit the customary right of unit self-defence.



In summary, efforts to link unit self-defence to the rights of individual and national self-defence have failed to overcome important conceptual difficulties. The best explanation is that unit self-defence stands alone as an inherent right under customary international law, limited by the constraints enunciated in Caroline and applicable only to military units. As demonstrated during the discussion on the Nicaragua case, the treatment of unit self-defence as a unique element of customary international law, quite separate from national self-defence helps to avoid the inconsistencies that arose in that judgement case. It also reinforces the notion that it is an inherent right, which is contrary to the existing Australian doctrine.

The legal basis of unit self-defence is more than academic - it provides the foundations upon which a commander can employ force in unit-self-defence and whether that right can be limited or modified by ROE or a superior commander, as Australian policy currently suggests. The overwhelming opinion of scholarships on the topic suggests that the right is inherent. This is particularly important noting the technological developments towards lethality. Finally, we need to remove self-defence from ROE and ensure the two are kept conceptually separate, with those differences understood and practised by all warfighters.

It is clear that the current Australian policy should be amended to reflect this view, and clarify the right - in situations where the threat is imminent and overwhelming, leaves no choice or means and no moment for deliberation, then there can be no room for doubt in the mind of a Commander using lethal force to protect his unit.