Recent Posts

Is Violating “Serious Obligations” of the INF Treaty the same as its “Material Breach”?

by Duncan Hollis

A few hours ago, the NY Times broke a story that the United States views Russian tests of a ground-launched missile as violating the 1987 INF treaty, formally (and lengthily) titled, “The Treaty Between The United States Of America And The Union Of Soviet Socialist Republics On The Elimination Of Their Intermediate-Range And Shorter-Range Missiles”.  According to the story, the State Department will publicly issue a report that says, among other things:

The United States has determined that the Russian Federation is in violation of its obligations under the I.N.F. treaty not to possess, produce or flight test a ground launched cruise missile (GLCM) with a range capability of 500 kilometers to 5,500 kilometers or to possess or produce launchers of such missiles,”

In addition, President Obama has notified Russian President Putin of the U.S. charges in a letter delivered today.

The U.S. move adds a new brick to the wall of tensions building in the U.S.-Russian relationship (others include Crimea, Russian support for Eastern Ukrainian separatists, the MH17 tragedy, not to mention Edward Snowden’s continuing presence in Moscow).  I assume the timing of the U.S. accusations is no accident.  Moreover, I find it interesting that in so many of these recent crises with Russia, the United States has consistently relied on law and legal argumentation to push against Russia’s actions (or inaction).  This case may be the most extreme example of such an approach since the issue here is entirely one of international law and treaty interpretation.  As such, it’s very much in the wheelhouse of Opinio Juris and its readers. I thought I’d start the conversation with a few preliminary thoughts (emphasis on the “preliminary” since we don’t have too many details to go on as yet).

For starters, the precise language used to describe Russia’s tests — a violation of its obligations under the I.N.F. Treaty” — appears quite significant (especially where it comes after reportedly extensive deliberation). Certainly, the concept of a violation is easy to grasp and has important political implications. For treaty lawyers, however, the term “violation” is not the language we’d expect to see where there’s non-compliance with a treaty’s terms. The Vienna Convention on the Law of Treaties (VCLT), which sets the customary international law rules in these cases, describes violations in terms of a treaty’s “breach”  More specifically, it articulates a set of remedies where breaches are “material” (see VCLT Article 60 here).  In this case, however, that key adjective — “material” — is nowhere to be found, suggesting the United States is not looking to invoke this VCLT provision.  But even if it were, in a move that has stumped generations of international law students, the VCLT’s remedies for a treaty’s material breach are quite limited — they entitle the non-breaching party to suspend or terminate its own obligations under the treaty in whole or in part (the VCLT also adds some procedural hurdles but these are largely ignored in State practice). Of course, there’s no evidence suggesting that the U.S. has any intention of suspending or terminating the INF Treaty; on the contrary, U.S. interests seem to lie squarely on keeping Russia obligated by the treaty as long as possible and forestalling any Russian move to withdraw from the INF Treaty (which Article XV allows it to do).  Simply put, the United States does not appear to consider Russia’s behavior as a material breach of the INF treaty nor want the remedies that label conveys; such a path would actually undercut the stability of the INF treaty’s continued performance for which the United States is pushing.

Second, just because the VCLT remedies are undesirable does not foreclose the United States from all legal leverage in this case. By using the term “violation . . . of obligations” the United States may be invoking a different set of international law rules … those of State responsibility.  Although the United States has been ambivalent to the UN’s Draft Articles on State Responsibility, those articles elaborate a detailed sets of obligations, rights and remedies where a State commits an internationally wrongful act (defined to include a breach of treaty obligations).  The offending State is required to cease (and not repeat) non-compliant behavior and the injured State(s) may engage in “counter-measures” to induce such a return to compliance. These counter-measures may include behavior previously categorized as a retorsion (lawful behavior such as canceling foreign assistance done in response to a prior breach) and a reprisal (behavior that would be unlawful but for the existence of the prior breach).  At present, the types of U.S. responses on offer described in Michael Gordon’s story are likely retorsions, but I assume other measures, including reprisals, could follow if Russia does not respond appropriately.

Taken together, these moves lend support to Bruno Simma and Christian Tams argument in my book that the law of state responsibility has proven more attractive to States than the VCLT’s remedies for treaty breach. That said, I do not mean to suggest that the VCLT is entirely irrelevant to this case.  On the contrary, its provisions on interpretation (Articles 31-33) are likely central to the U.S. claim of a Russian violation.  What’s more, I’d expect Russia to offer its own interpretation to the contrary employing the same interpretative framework (not to mention counter-claims of U.S. violations as described in tonight’s story).

All in all, there’s quite a bit here that should be of interest not just to those who care about arms control and nonproliferation, but international law and international relations more generally.  I’d be interested to hear what others think the U.S. claim suggests and how you see things playing out? Comments welcome.

The Man Who Would Be King, Daddy’s Little Princess, and their Territorial Claim

by Chris Borgen

There are many dads who have played make-believe with their little girls, perhaps taking the part of kindly king to his daughter’s princess.  Not many people have turned this game into an international legal incident concerning state formation.  But  at least one man has. According to the Washington Post:

Jeremiah Heaton was playing with his daughter in their Abingdon, Va., home last winter when she asked whether she could be a real princess.

Heaton, a father of three who works in the mining industry, didn’t want to make any false promises to Emily, then 6, who was “big on being a princess.” But he still said yes.

“As a parent you sometimes go down paths you never thought you would,” Heaton said.

Within months, Heaton was journeying through the desolate southern stretches of Egypt and into an unclaimed 800-square-mile patch of arid desert. There, on June 16 — Emily’s seventh birthday — he planted a blue flag with four stars and a crown on a rocky hill. The area, a sandy expanse sitting along the Sudanese border, morphed from what locals call Bir Tawil into what Heaton and his family call the “Kingdom of North Sudan.”

There, Heaton is the self-described king and Emily is his princess.

Wow. Heaton just upped the ante for all non-royal dads. The Washington Post also reports:

Heaton says his claim over Bir Tawil is legitimate. He argues that planting the flag — which his children designed — is exactly how several other countries, including what became the United States, were historically claimed. The key difference, Heaton said, is that those historical cases of imperialism were acts of war while his was an act of love.

“I founded the nation in love for my daughter,” Heaton said.

That’s sweet. Really. But let’s turn to the international legal argument… (more…)

Emerging Voices: Horizontal and Vertical Dimensions of International Law in U.S. Courts

by Zachary Clopton

[Zachary Clopton is the Public Law Fellow at the University of Chicago Law School.]

For decades, scholars and practitioners of international law in the United States have focused on the federal courts.  The combination of diversity, alienage, federal question, and Alien Tort Statute (ATS) jurisdiction largely justified this focus.  But in the wake of decisions such as Morrison and Kiobel, some of these scholars and practitioners have turned to state courts and state law to vindicate international norms (1, 2).  To give one example, New York state courts are adjudicating foreign-law claims against the Bank of China arising from its alleged facilitation of Hamas and Palestine Islamic Jihad attacks in Israel.

The attention to states may prove to be a positive development, but notably it has tended to rely on judicially created rights—common law claims under state or foreign law, or customary international law.  What about state political branches?  Is there is a role for governors and state legislatures, and should internationalists spend some of their energy lobbying these state-level political actors?

From a policy perspective, as well as from a doctrinal and constitutional one, international litigation in U.S. courts raises both horizontal (separation of powers) and vertical (federalism) questions.  Although some judges and scholars object to international law in all of its forms, and others applaud any expanded role for international law, acknowledging the independent horizontal and vertical dimensions opens up more nuanced options.


Emerging Voices 2014 Kicking Off Today

by Jessica Dorsey

Last year’s inaugural Emerging Voices symposium was a big success, so today we’re kicking off our second annual edition. Through mid-August, we will be bringing you a wide variety of posts written by graduate students, early-career practitioners and academics.

Tune in over the next several weeks if you’d like to read more about litigation of international law in domestic courts, interstate arbitration, statelessness, and rape as a war crime–to name just a few of the topics some of our contributors will cover. Please feel free, as usual, to weigh in on the discussion. Thanks for following us here on Opinio Juris–we hope you enjoy this second edition of our Emerging Voices Symposium!

R.I.P., Professor William T. Burke, Leading Law of the Sea and International Fisheries Scholar

by Julian Ku

Professor Yann-huei Song of the Academia Sinica here in Taipei has notified me of the recent passing of his friend and fellow Law of the Sea scholar William T. Burke of the University of Washington.  His Seattle Times obituary is here.  Professor Burke’s academic publications included The Public Order of the Oceans (coauthored with Myres S. McDougal), published in 1962 and revised in 1987, and The New International Law of Fisheries(1994; translated into Japanese, 1996).  Before joining the UW faculty in 1968, Professor Burke taught at Yale Law and Ohio State Law.  There is a nice 2008 profile of him in the UW alum magazine here.  The following is a personal note from Professor Song: 

We both are students of the New Haven School for the legal studies, where I met Professor Myres S. McDougal when attending the annual policy science meeting held at Yale Law School. His book entitled THE NEW INTERNATIONAL LAW OF FISHERIES: UNCLOS 1982 AND BEYOND (Oxford: Clarendon Press, 1994) is one of the most authoritative textbooks for students who are interested in studying the international fisheries law. In addition, the book he co-authored with Myres S. McDouglas, THE PUBLIC ORDER OF THE OCEANS, A CONTEMPORARY INTERNATIONAL LAW OF THE SEA (Yale University Press, 1962), is a classic writing on law of the sea issues with the application of the new policy-oriented approach to the law of the sea. This book is one of four volumes in which McDougal and his associates approached the entire field of international law.  I met Professor Burke also at the UC-Berkeley’s Law of the Sea Institute’s meetings. As far as I can remember, he was critical to the US government’s position and policy of fisheries and law of the sea issues at the time.
Students of international law, in particular, international fisheries law, have been influenced by his writings. If I have the honour, on behalf of the international law of the sea community, in particular, the Chinese (Taiwan) Society of International Law, I wish to express our heartfelt condolences to the family of Professor Burke for their sad loss. 

Weekly News Wrap: Monday, July 14, 2014

by Jessica Dorsey

Your weekly selection of international law and international relations headlines from around the world:


  • In Nigeria, Boko Haram-style violence radiates southwards.
  • Ebola continues to spread in Sierra Leone, Liberia and Guinea, with a combined 44 new cases and 21 deaths between July 6 and 8, the World Health Organisation has said.



Middle East and Northern Africa



Let Me Be Clear: Taiwan Should Be Defended, Even Though the Defense is Illegal

by Julian Ku

So I managed to anger lots of folks (mostly on twitter) with my post Friday (republished in the Diplomat and RealClearWorld yesterday) on the international legal problems created by any Japanese intervention to defend Taiwan from an attack by China.  I don’t mind angering people (especially on twitter), but I do want to make sure they are angry with me for the right reasons. Many readers seem to think I want China to invade Taiwan, which is in fact the complete opposite of my policy goal.   So let me offer some clarifications of my position on policy, and a few rebuttals of legal responses to my arguments.

1) Policy: I am squarely in favor of U.S. military intervention to defend Taiwan against any PRC military attack. I am even in favor of intervention in the case of a declaration of independence by Taiwan as long as Taiwan acts in a responsible way so as not to threaten China’s national security.(My only hesitation on this is the cost to the US, but not on the merits of Taiwan’s case). Given how strong China is these days, I am pretty sure Taiwan could not be a real military threat to China (nor would it want to be).  Whether the US would actually protect Taiwan is the zillion dollar policy question that I don’t have the answer to.  I hope it does, but I don’t know if it will.

2) Law: However, my favored US policy is in deep tension with, or even direct conflict with, traditional understandings of the international law governing the use of force.  For those of us who love and cherish Taiwan, it is no use pretending as if the law supports a US or Japanese military intervention to defend Taiwan. It doesn’t. It would be better for all concerned if we faced this legal problem head-on rather than try to come up with complicated not-very-persuasive workarounds.  Here are the two most obvious workarounds, raised in this very angry and excited post by Taiwan-expert J. Michael Cole:

a) Responsibility to Protect and Humanitarian Intervention
Here is a simple response: R2P are non-binding principles that, even if they were binding, seems to require Security Council consent.  Humanitarian intervention remains deeply contested and doubtful in international law, and would not apply to Taiwan in any case until it was probably too late. Kosovo is a great example of how contested this doctrine is. Syria is another.

b) The ROC is a separate legal entity.
I get that this is a complicated issue, but I don’t think I am “misreading” historical documents when I write that i) the US recognizes the PRC as the government of China and that the US accepts that Taiwan is part of China; 2) Japan recognizes the PRC as the government of China, and Japan accepts that Taiwan is a part of China.  Sure, neither country recognizes that Taiwan is a part of the PRC, but both the US and Japan have made clear that China is a single legal entity that includes Taiwan, and that the PRC is the sole government in charge of this entity. We can futz around the details, but there is a reason why neither the US nor Japan (nor almost anyone else) have diplomatic relations with Taiwan.

Here is one interesting and unexpected policy consequence of Taiwan’s current legal position: it would be safer from a legal perspective for Taiwan to declare independence, since that would protect it from this legal problem I’ve identified. Of course, that legal position would probably be the least safe from a policy perspective, since it is the mostly likely to spark a Chinese attack.

Which brings me to my real point: the increasing irrelevance of Article 51 of the UN Charter to decisions by major powers on whether to use military force. The decision on whether to defend Taiwan should not depend on workarounds for Article 51. It should depend on the combination of moral values and national interests the US and Japan consider worth protecting here in Taiwan. I think Taiwan is worth protecting, but it is important to recognize that the law is not on Taiwan’s side.

Why “Lawfare” Won’t Deter China in the South China Sea

by Julian Ku

Harry J. Kazianis, the managing editor of The National Interest, has a smart post discussing the risk that the U.S. is taking if it tries to take more aggressive action to counter China in the South China Sea.  Essentially, he argues the U.S. has no effective strategy to counter China’s “non-kinetic” strategy to subtly alter the status quo by using non-military assets to expand control and influence in the region.  I agreed with Kazianis all the way until he offered his own solution:

There only seems one solution to the various territorial disputes in the region—specifically, what some are calling “lawfare.” All of the various claimants that have disputes with China in the South China Sea should appeal collectively to any and all international bodies that could possibly hear their claims. Only together can they hope to get Beijing to halt its aggressive actions.

He goes on to cite the Philippines claim against China in the UN Law of the Sea arbitration system as a possible model for other nations.

“Lawfare” or international law litigation is not going to be an effective counter to China here for at least two reasons (one legal, one policy-based):

  • 1) China has opted out of any “compulsory” system of international dispute resolution that would rule on its territorial claims in the South China Sea (or anywhere, for that matter).  This “opt-out” is perfectly legal and may very well prevent the Philippines from even making their full case to the UNCLOS arbitration tribunal.  There are no other legal institutions that have jurisdiction.  So the only way “lawfare” can work here is if China consents to arbitration. But if Kazianis is right that this is a strategy by China’s neighbors to block its expansion, then why would China ever agree to arbitration?
  • 2) Even if compulsory jurisdiction were somehow found in one of these international bodies, there is very little chance that China would feel compelled to comply with any negative ruling.  This is not a China-specific problem, but rather a problem almost every country faces when considering arbitration over territorial disputes.  The effectiveness of tribunals in these contexts is highly limited since they depend for enforcement on the individual state-parties.  This is why voluntary arbitration tends to work better than compulsory arbitration in these kinds of territorial disputes.  The U.S. and Canada, for example, have managed to settle (most of) their often contentious land and maritime borders through a combination of non-arbitral commissions, and then special bilateral arbitrations.  In the famous “Gulf of Maine” case, the U.S. Senate actually approved a special treaty with Canada to send a maritime dispute to a special chamber of the ICJ.  Although clunky, this model is far more likely to succeed in getting state compliance.

So while I agree with Kanianis and other commentators that China needs to be deterred from its current strategy in the South China Sea, I am fairly confident the use of “lawfare” will not be a way to accomplish this goal.

Events and Announcements: July 13, 2014

by An Hertogen

Calls for papers

  • Yale Law School is hosting its 4th Doctoral Scholarship Conference on November 14-15, 2014. The theme for this year’s conference is ‘law and responsibility’. The conference is open to current doctoral candidates, both in law and law-related disciplines, and those who graduated during the previous academic year. The deadline for the submission of abstracts is August 1, 2014. More information is available here and on Facebook.
  • The Board of Editors of Trade, Law and Development [TL&D] is pleased to invite original, unpublished manuscripts for publication in the Winter ‘14 Issue of the Journal (Vol. 6, No. 2) in the form of Articles, Notes, Comments, and Book Reviews. Manuscripts received by September 17, 2014 pertaining to any area within the purview of international economic law will be reviewed for publication in the Winter ‘14 issue. TL&D has the distinction of being ranked the best journal in India across all fields of law for three consecutive years and the 10th best trade journal worldwide by Washington and Lee University, School of Law. For more information, please go through the submission guidelines available at or write to the editors.
  • The Utrecht Journal of International and European Law,  is issuing a call for papers in relation to its forthcoming 80th edition on ‘Privacy under International and European Law’. More information can be found here.
  • Melbourne Law School will host the seventh annual Melbourne Doctoral Forum on Legal Theory on December 1–2, 2014. The Forum brings together research students from all academic disciplines to engage with social, political, theoretical, and methodological issues raised by law and legal theory. This year’s workshop challenges participants to think about law legal theory in its transnational and domestic orders and forms through the concept of the borderline. Borderlines constitute the boundaries between and within legal orders. While borders assert their permanency and inviolability, guarding who the law protects and who it disregards, we know that they are contingent, moveable, transient and above all human creations. The word ‘borderline’ evokes many conflicting meanings — sharp divides, permeations and transgression, centre and periphery, the invisibility of some distinctions and the starkness of others, abnormality and a lack of normalcy, and the imprecision and vagueness of resting ‘on the borderline’ — each of which speaks to the relations between different legal orders that take on many forms, all of varying permanency. Where do the borders fall between and within the transnational and domestic, and why? How should we theorise the way the interactions between these orders take place? And how are these borders dealt with in different legal traditions and cultures? More information can be found on the Forum’s website, in the call for papers or on Twitter.


  • During a Round Table on 23 May 2014 organized by the Amsterdam Center for International Law (ACIL) and the Amsterdam Centre for European Law and Governance (ACELG) of the University of Amsterdam a number of experts have presented their thoughts on key aspects of Secession within the Union. This has resulted in a collection of think pieces that identify and outline a number of outstanding issues of both public international law and EU law. The integral booklet and/or the individual short essays can be downloaded here.

Last week’s events and announcements can be found here. If you would like to post an announcement on Opinio Juris, please contact us with a one-paragraph description of your announcement along with hyperlinks to more information.

Weekend Roundup: July 5-11, 2014

by An Hertogen

This week on Opinio Juris, we hosted a symposium on Ian Henderson and Bryan Cavanagh’s paper on Military Members Claiming Self-Defence during Armed Conflict. In a first post, Ian and Bryan discussed when self-defence applies during an armed conflict, while their second post dealt with collateral damage and “precautions in attack”. Their third post addressed prohibited weapons, obedience to lawful commands, and a ‘duty’ to retreat, and summarized the main points of their paper. In their final post, they focused on the concept of unit self-defenceJens Ohlin and Kinga Tibori-Szabó commented.

In our regular posts, Kevin posted Yuval Diskin’s comments on the escalating situation in Israel and the Occupied Territories and pointed out a misrepresentation in ABC’s reporting on the conflict. Julian argued why a Japanese intervention in Taiwan would violate international law, but should still be done if it came to defending Taiwan against a Chinese attack. Peter pointed out three distortions behind July 4 naturalization ceremonies

Finally, Jessica wrapped up the news.

Many thanks to our guest contributors and have a nice weekend!

Guest Post: Remarks on Henderson & Cavanagh Guest Post on Unit Self-Defence–Perspectives from the Courtroom

by Kinga Tibori-Szabó

[Kinga Tibori-Szabó currently works for the Legal Representative of Victims at the Special Tribunal for Lebanon. She is also a New York attorney. In 2012, she won the ASIL Lieber Prize for her book Anticipatory Action in Self-Defence.]

What could be more straightforward than a unit commander’s right to defend his unit, or other specified units against hostile acts and hostile intent? But as obvious this right may seem in the military sense, as eclectic and elusive its legal nature can be.

Ian Henderson and Bryan Cavanagh rightly point out that unit self-defence, in the legal realm, can be thought of both as a unit-level derivate of states’ inherent right of national self-defence and as a form of the criminal law concept of personal self-defence. It is also viewed as a corollary of the fundamental human right to life.

Indeed, as pointed out by the authors, if the defensive action taken at the unit level ends up being litigated at the International Court of Justice, it will be the responsibility of the state that will be in question and the legal issue will be whether the right of national self-defence applies.

Equally, Article 31(c) of the ICC Statute and ICTY jurisprudence have approached the question of unit-level action from the perspective of personal self-defence, as a ground excluding criminal liability. The ICTY stated that the “notion of self-defence may be broadly defined as providing a defence to a person who acts to defend or protect himself or his property (or another person or person’s property) against attack” and applied that definition to questions regarding the legality of forceful action taken by military units (Kordic and Cerkez, Judgment, 2001, para. 449).

Add to that the fact that many domestic jurisdictions do not recognize unit self-defence as an independent legal concept, albeit its substance is acknowledged, usually in the form of collective personal self-defence, as a right of a unit commander (have a look at the General Report 19th Congress ISMLLW, Quebec). Even in jurisdictions where unit self-defence is explicitly acknowledged, its content might not be identical. For instance, the US SROE define hostile acts to include force used directly to preclude or impede the mission and/or duties of US forces, including the recovery of US personnel and vital US government property, while other states define the term more narrowly.

Against this background, it seems sensible to aver that unit self-defence should be viewed as a ROE concept that has underlying law and legal consequences, but is not a legal term of itself. Or as Kalshoven and Fontein noted, “the true significance of the right of unit self-defence may lie in its cohesive power”.

Then again, as a lawyer trapped in the courtroom most of the time, I cannot help thinking of that odd situation, at the international judicial level, when none of the mantles we just bestowed on unit self-defence would fit. Every operational term, if it ends up playing a role in (international) courts, will have to be associated with a legal term or drawn from a legal basis. Take, for instance, one of those quintessential on-the-spot-reaction scenarios of a naval vessel under sail, being attacked while transiting between the harbours of allied nations. If the attack, because of its nature and scale, reaches the threshold of an armed attack, the inherent right of national self-defence can be invoked and force may be used within the limits of that right. In such a case, unit self-defence would be absorbed within the jus ad bellum concept. If the use of force triggers an armed conflict, the law of armed conflict will become applicable, in which case, as discussed by Henderson & Cavanagh as well as Jens David Ohlin, the concept of self-defence (unit or personal) becomes arguably redundant. But what if the attack on the vessel does not reach the threshold of an armed attack and the response does not trigger an armed conflict? In that nebulous territory, where neither jus ad bellum nor the law of armed conflict applies, we are left with personal self-defence, in its collective form. Obviously, if the operational term on which the unit’s action is based can be easily linked with provisions similar to those contained in Article 31(c) of the ICC Statute, then the problem is solved. But such provisions might not be readily available (the ICTY, ICTR and STL statutes do not expressly assert an exception of personal self-defence), and the court will have to rely on its case-law or develop relevant jurisprudence. But what if the ROE of the vessel’s nation state allows for a unit self-defence that is more permissive than the personal defence case-law of the international court? Or what if the definition of a unit in the domestic operational term is different from how the court’s jurisprudence defines defence of others or defence of property? Or what if there is no such definition in the case-law? Or what if other gaps, stemming from the different nature of the two terms (unit self-defence as a permissive rule authorising the use military force v. personal self-defence as a narrowly interpreted exception to criminal responsibility) would make it cumbersome to convert the operational term into the legal? Wouldn’t these situations warrant the acknowledgment of an independent legal term of unit self-defence, with its own elements and limits, rather than fiddling with personal self-defence, to fit a purpose it was not primarily meant to fulfil?

The odd situation, however, may never arise. It may as well be that unit self-defence will make more sense as an operational term, capable of being morphed into various, related legal terms. In any case, the debate should be kept alive and, if pertinent, room should be left for an independent legal term of unit self-defence to develop.

Guest Post: Unit Self-Defence

by Ian Henderson and Bryan Cavanagh

[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. This is the third in a four-part series. The first post can be found here (along with a response here), the second here and the third here.]

In this final post, we briefly discuss the concept of unit self-defence. Unit self-defence is a term used in rules of engagement (ROE) and can be defined as ‘the right of unit commanders to defend their unit, or others units of their nation, and other specified units against hostile acts or hostile intent’ (see the annex D of the San Remo ROE Handbook). In some militaries, along with being described as a right, it is also described as an obligation (see CJCSI 3131.01B, U.S Standing Rules of Engagement). In other words, a commander is positively required to act in unit self-defence and can be held accountable for not doing so.

In our view, and with due respect to those who have argued that unit self-defence has an independent legal basis, the better approach is to view unit self-defence purely as an ROE concept (much like the terms observed indirect fire and unobserved indirect fire) that has underlying law and legal consequences but is not a legal term in and of itself. Considered that way, unit self-defence can be thought of as:

a) a form of delegated authority from the national command chain of a State to exercise a State’s right of national self-defence in limited circumstances and in a constrained fashion;

b) a reminder of the criminal law authority to act in self-defence to protect oneself and protect others, (recalling that the criminal law concept of self-defence allows a person to not only defend his or herself, but also to defend another person where the person to be aided is in a situation where the law would allow that person to act in self-defence); and

c) an order or command to use military force when certain ‘triggers’ are present.

We believe deconstructing unit self-defence in this way is helpful as it focuses on the legal basis for any given use force (or non-use of force if a commander failed to act in unit self-defence) based on the jurisdiction in which the issue would be litigated. For example, if the matter is being litigated in the International Court of Justice, it will be the State that is the party. As such, the legal issue is likely to be whether the State had a right to use force. Conversely, in a criminal proceeding in a domestic court or international tribunal, it will be individual military members who are being prosecuted; and so, combatant’s privilege aside, the issue is more likely to be whether the individual had the right to use force. And finally, through ROE a commander (or for that matter, any other military member) can be ordered to use force (and held accountable for not doing so) where the circumstances are such that under the law of self-defence they would be legally permitted but not compelled to use force in defence of another.

We are very thankful to the editors of OpinioJuris for giving us this opportunity, as well as for the useful comments and discussion from the readers.