Guest Post: Military Members Claiming Self-Defence During Armed Conflict–Often Misguided and Unhelpful

Guest Post: Military Members Claiming Self-Defence During Armed Conflict–Often Misguided and Unhelpful

[Ian Henderson is a group captain in the Royal Australian Air Force and is currently posted as the Director Military Law Centre and Deputy-Director Asia-Pacific Centre for Military Law. Bryan Cavanagh is a squadron leader in the Royal Australian Air Force and is currently posted as a legal training officer at the Military Law Centre and Asia-Pacific Centre for Military Law. This note was written in their personal capacities and does not necessarily represent the views of the Australian Government or the Australian Department of Defence.]

We would like to thank the editors of Opinio Juris for allowing us this opportunity to discuss our draft book chapter on the how the concept of self-defence under criminal law operates in relation to military members during an armed conflict. We would also like to thank the ASIL Lieber Society and the judges who kindly awarded our paper a Certificate of Merit (second prize) in the 2014 Richard R. Baxter Military Prize for ‘a paper that significantly enhances the understanding and implementation of the law of war’.

The Law of Armed Conflict (LOAC) reflects a balance between military necessity and humanity. Potentially upsetting this balance is an apparent trend towards relying on self-defence under criminal law as a justification for the use of force by military members during armed conflicts. We argue that this trend is based on a misunderstanding of the scope self-defence when applied in light of the combatant’s privilege.

As the relevant law that would apply to a claim of self-defence depends upon the jurisdiction, we limited our analysis to the Australian Commonwealth Criminal Code and the Rome Statute. We would be very interested to hear about how our analysis might apply in other jurisdictions.

We have split the issues up into four discrete posts. In this post, we discuss the circumstances where self-defence does and does not apply during an armed conflict. This also entails discussing the combatant’s privilege.

In our next post, we will deal with whether it is lawful under the criminal law concept of self-defence to cause incidental injury (aka, collateral damage) and whether the law relating to self-defence imposes requirements similar to the ‘precautions in attack’ under article 57 Additional Protocol I.

The third post will be a comparison of how LOAC and the law of self-defence deal with a number of discrete issues like the use of prohibited weapons, obedience to lawful commands, and ‘duty’ to retreat.

And in the final post we will briefly address the rules of engagement (ROE) concept of unit self-defence.

You say tomato, I say tomahto

Self-defence is not a unitary concept, but rather has different legal and operational meanings. It is vital to distinguish between the different meanings and ask in what context is the term ‘self-defence’ being used. Our chapter is about an individual claiming self-defence when facing potential criminal (or disciplinary) charges. It is not about a State’s right of self-defence under article 51 UN Charter (or customary international law).. Whether or not a State has a right to use force in national self-defence is a separate and distinct issue from whether an individual is not guilty of crime under the relevant self-defence provisions pertaining in a particular criminal jurisdiction.

Combatant’s privilege

Self-defence has a narrower application on the battlefield than is generally understood. First, self-defence does not apply when a person is responding to a lawful act (eg, I cannot claim self-defence as a legal basis of for my use of force against a police officer who is exercising a lawful arrest). Second, and as a corollary to the first point, self-defence does not arise when military members are otherwise authorised by law to use force against another person.

Where a State is engaged in an international armed conflict, a combatant is entitled to the combatant’s privilege. Accordingly, where a combatant from State A shoots at a combatant from State B, the law of self-defence is generally both irrelevant and inapplicable. We say ‘generally’, as self-defence would have some potential relevance if one of the combatant’s was using a prohibited weapon, was firing on a combatant who was hors de combat or was in some other way not fighting in accordance with the LOAC (this point will be discussed in a later post).

The situation is different in a non-international armed conflict (NIAC). In a NIAC, it is clear that the non-government forces do not have the equivalent of the combatant’s privilege (we refer to an ‘equivalent’ of the combatant’s privilege because in a NIAC there are technically no ‘combatants’ on either side — ‘combatant’ is a term of art reserved for international armed conflicts). Therefore, if a member of the non-government forces shoots a member of the government forces in a manner that otherwise complies with LOAC, that person can still be prosecuted under domestic law (recall that it is not a crime under international to be an unprivileged belligerent — a member of the non-government forces does not commit a crime under international law simply by engaging in acts of hostilities against government forces). Accordingly, a member of the government forces could, among other potentially relevant legal bases, rely on self-defence when responding to an attack from a member of the non-government forces.

It is less clear whether the government forces enjoy the equivalent of the combatant’s privilege. This is important for many reasons, not the least of which is that the government forces may not win the armed conflict and the new government may not be predisposed to exercise any prosecutorial discretion in favour of the now former government forces. There is no treaty law on the point one way or the other, nor is the issue clearly addressed in customary international law. Most commentators do not seem to address the issue one way or the other; although a few commentators do positively argue that such a privilege either does, or at least should, exist. The best that can be said at the moment is that the issue remains in doubt.

If the equivalent of the combatant’s privilege does attach to the government forces, it follows that LOAC (and where applicable, any implementing domestic law – see point 2 below) and not the law of self-defence provides the legal basis for attacks on the non-government forces. This is the case whether such attacks are offensive or defensive in nature, as self-defence does not arise when military members are authorised by law to use force against another person. Further, the non-government forces could not rely on self-defence as a legal basis for using force in response to an attack by the government forces as self-defence does not arise in response to a lawful use of force.

Two further issues related to combatant’s privilege that we discuss in the chapter but will not go into detail here are:

1. Whether the combatant’s privilege is a personal immunity (ie, for any acts they perform) or a functional immunity (ie, only those acts that can be attributed to military operations)? We conclude that while certain arguments support the view that the combatant’s privilege should be treated as a functional immunity, and in the opinion of the authors that is the better interpretation, the matter is not beyond doubt.

2. Does the combatant’s privilege apply only to foreign domestic law or also the domestic law of the military member? As a matter of international law, whether the combatant’s privilege extends to bar prosecution of a military member under his or her own State’s criminal law is currently unclear. Perhaps the most important point our research shows is that for killing in the course of armed conflict not to amount to murder in a military member’s own domestic law, there either needs to be a statutory provision to that effect (we refer to a US example), or for the crime of murder not to apply as a matter of common law definition or statutory construction (we refer to a UK example).

The main cases we discuss concerning combatant’s privilege and domestic law are: Al-Marri v Pucciarelli, 534 F3d 213 (4th Cir, 2008); Public Prosecutor v Oie Hee Koi and others (Malaysia) [1967] UKPC 21; R v Page [1954] 1 QB 170; R v Gul (Appellant) [2013] UKSC 64; and United States v. McMonagle, 38 MJ 53 (CMA 1993).

If anyone is aware of further cases, we would be very interested in getting the citation.

In our next post, we will deal with whether it is lawful under the criminal law concept of self-defence to cause incidental injury (aka, collateral damage) and whether the law relating to self-defence imposes requirements similar to the ‘precautions in attack’ under article 57 Additional Protocol I.

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I would be careful re: phrases such as “exercising a lawful arrest” — since the issue is how? or re: military “authorized by law to use force” — since, as you note, the issue can become how? [e.g., not if the military person violates the laws of war] Also, regarding combatant immunity during a NIAC, since the matter is “in doubt” there cannot be customary int’l law allowing such an immunity (since there is no general pattern of opinio juris to support it). Also, I have written that under CIL there is no immunity — no general “doubt” With respect to you primary focus, I suspect that the main problem relates to how international law is or is not part of a domestic legal process — e.g., through direct incorporation as treaty law of the U.S. or CIL (e.g., recall Ex parte Qurin (1942), this Court has applied the laws of war re: rights, status, duties since the Founding — and there was no federal statute incorporating the laws of war until the 1916 Articles of War, now similarly 10USC sec. 818, 821, as supplemented by fed. stats. re: fed. dist. ct. civil and criminal jurisdiction); indirect incorp. (e.g., as… Read more »

Ian Henderson
Ian Henderson

Jordan, Thanks for your comment. For the moment, we would like to reply to whether the equivalent of the combatant’s privilege might exist for government forces in a NIAC. We believe there might be more State practice and opinio juris than is generally believed. Take, for example, the recent conflict in Afghanistan. While we know you have written that it is an IAC, most States believe it is a NIAC. Whether they are right or not is irrelevant for our point, which is as States believe it is a NIAC, why aren’t they prosecuting their soldiers for killing members of the Taliban? For example, under Australia’s military disciplinary law, the offence of murder is prima facie applicable. In addition, there is a positive legal obligation under a Defence Instruction for other military members to report suspected offences. Arguably, not just the lack of prosecutions (which, at a stretch, could be attributed to policy), but even the lack of notifications (which are mandatory, not discretionary) are because there is a general belief that no offence has been committed. This belief appears to be shared by the international community, which has not called for investigations, let alone prosecutions, of government forces who… Read more »


Ian: unfortunately the failure by many states to prosecute those who are rasonably accused of war crimes is negative practice but one cannot safely infer what the relevant patterns of opinio juris are–esp. when even such states claim that other states or int’l tribunals should prosecute or that it is appropriate that they do so. Australia refused to carry out prosecutions of former Nazi accused, apparently when Australia discovered that there were other citizens in country that were reasonably accused — see, e.g., article by Graham Blewitt (sp?). And President Obama has absolutely failed to initiate prosecution of GW Bush, Cheney, Rice, Addington,Yoo, Rizzo, and so many others (most of whom have admitted complicious involvement with Bush’s admitted “program” of secret detention (i.e., forced disappearance) and harsh interrogation tactics (i.e., torture, cruel treatment, etc.).


with respect to “cobatant immunity,” readers might check 28 Yale J.Int’l L. (2003) at pp. 330-333, available at
and with respect to judicial power in the U.S. to identify, clarify, and apply international law, especially the laws of war, regarding the status, rights, and duties of persons and competencies of governments, etc., see, e.g., 44 Harv. Int’l L.J. (2003) at pp. 514-524, available at — quoted in Hamdi v. Rumsfeld, 542 U.S. 507, 520-21 (2004).

Kevin Jon Heller

Have the relevant parties in Afghanistan asserted that their soldiers cannot be prosecuted domestically because they possess the combatant’s privilege in NIAC? In the absence of such opinio juris, I know of no extant theory of acquiescence that would permit you to infer from the international community’s silence that they accept the existence of such a privilege. The international community is not required to disagree with legal claims that a state does not actually make in order to avoid creating new customary rules.

Ian Henderson
Ian Henderson

Jordan & Kevin,

We appreciate that a definitive position on State practice concerning combatant immunity in a NIAC for government forces is, like a lot of CIL, hard to establish. Nonetheless, we do still think it is telling that, to the best of our knowledge, there have been no prosecutions, or even calls for prosecution, of soldiers who have killed in a NIAC in jurisdictions that have independent prosecutors. Have Amnesty International or Human Rights Watch called on governments to investigate? Why is it that there is strong academic and NGO concern about armed UAVs operated by the CIA but not by the USAF outside of an IAC? Where is the ‘open letter’ signed by academics and nobel laureates calling for, at least, an investigation?

We should add that we are not positively asserting that there is a CIL rule of combatant’s privilege for government forces in a NIAC. Rather, we are saying it is a significant legal issues that requires consideration, especially in jurisdictions like Australia where prima facie there is no apparent legal reason why the killing of an insurgent by an Australian soldier does not meet all of the required elements for the offence of murder.


[…] “Military Members Claiming Self-Defence During Armed Conflict–Often Misguided and Unhelpful” by Ian Henderson and Bryan Cavanagh; and Jens Ohlin’s response: “Henderson & Cavanagh on Self-Defense & The Privilege of Combatancy” […]