The Airstrikes against Islamic State in Iraq and the Alleged Prohibition on Military Assistance to Governments in Civil Wars

Written by

Since the initiation of the US-led airstrikes against Islamic State (or ISIL) forces in Iraq and Syria in August and September of last year, the legality of the strikes in Syria has been the subject of much discussion. Much of the focus has been on whether collective self‑defence – of Iraq – allows the use of force against non-State actors in foreign territory (Syria), where the territorial State (Syria) is ‘unable or unwilling’ to stop the attacks itself. However, the legality of airstrikes occurring on Iraqi territory does not appear to have occasioned any discussion at all (although see this previous  post on the debate in the British House of Commons on authorising the use of force in Iraq). The presence of consent by the internationally recognised government of Iraq  to the airstrikes (see here) seems to make legality of foreign military action against Islamic State  under the jus ad bellum so obvious as not to require much commentary. However, a closer look at the scholarship on consent to the use of force reveals that the legality of what has variously been called ‘intervention by invitation’ or ‘military assistance on request’ has traditionally been more contentious than this simple statement would suggest. As discussed below, many scholars, and indeed some States, have suggested that there is a general prohibition on military assistance to governments in a situation of civil war or internal rebellion. This suggestion was particularly prominent in the Cold War era and seemed to represent an attempt to limit indirect uses of force by the superpowers. The rule is said to be derived from the prohibition of intervention in the internal affairs of other states, as well as from the principle of self-determination. The argument made by those in support of the rule is that intervention even with the consent of the government denies the people the right to govern their own affairs and to determine their political future. In short, on this view international law guarantees the right to rebel against the government. Others have doubted that a rule prohibiting assistance to governments in civil wars ever did emerge. This post seeks to demonstrate that recent state practice relating to the use of force in Iraq against Islamic State suggests that the evidence of opinio juris in relation to that rule is at present quite weak.

Support for a Rule Prohibiting Military Assistance to Governments in Civil Wars

According to a 1975 resolution of the Institut de Droit International on “The Principle of Non-Intervention in Civil Wars”, “[t]hird States shall refrain from giving assistance to parties to a civil war which is being fought in the territory of another State.” The resolution defines a “civil war” as a non-international armed conflict: a) between the established government of a State and one or more insurgent movements whose aim is to overthrow the government or the political, economic or social order of the State, or to achieve secession or self-government for any part of the State, or b) between two or more groups contending for control of the State in the absence of an established government. The resolution does recognize exceptions allowing the provision of “purely humanitarian aid” and a potential right of “counter-intervention” where illegal intervention has already occurred in aid of the other side in the civil war.

The existence of a prohibition similar to that set out in the 1975 IDI resolution has been recognized by eminent legal scholars. In a significant piece which includes a careful compilation of practice, Louise Doswald-Beck, writing in 1985, stated that “there is, at least, a very substantial doubt whether a State may validly assist another government to suppress a rebellion”, at least in the form of the sending of troops (arms transfers, in contrast, may be legal). According to Christine Gray, “[i]f there is a civil war rather than mere internal unrest, it has come to be accepted that there is a duty not to intervene, even at the request of the government, in the absence of UN or regional authorisation”, unless there has been prior foreign intervention against the government.  Olivier Corten confines the permissible use of force with consent to “riposting to outside interference or protecting nationals, without extending to the settlement of internal strife.” In support of this view are Christakis and Bannelier, writing on this blog and elsewhere.  Moreover, statements by States can be found to support a restrictive view of the legality of consensual use of force in civil war situations. A British Foreign Office policy document of 1984 (quoted in [1986] BYIL 616) stated that “any form of interference or assistance is prohibited (except possibly of a humanitarian kind) when a civil war is taking place and control of the state’s territory is divided between warring parties”, although it also acknowledged an exception allowing “counter-intervention” in favour of one side of a conflict in response to previous outside intervention on the other side.

Opposition to a Rule Prohibiting Military Assistance to Governments in Civil Wars

However, the restrictive view of the legality of consensual force is far from universally accepted: scholars like Yoram Dinstein, Eliav Lieblich and Gregory H Fox argue that that any general prohibition on military assistance to governments faced by civil war is inconsistent with State practice. Writing relatively recently, Fox gives as an example the apparent acceptance by the international community of the legality of French military intervention in support of the beleaguered Malian government in 2013, despite – or perhaps because of – the fact that Islamist rebels controlled the north of the country and appeared to be on the verge of a drive towards the capital.

At the level of principle, the equation of situations of civil war with the exercise of the right to self-determination seems problematic. Though it is conceivable that “a people” might take up arms as a means of asserting that right, it cannot be said that just because there is an armed group that has sufficient military means to engage in what has become a civil war, this means that right to self-determination is engaged. As Lieblich argues, this “condones the view that the fulfilment of self-determination is a corollary of a party’s capability to effectively use violence.” The ability of an armed group to conduct a civil war does not necessarily indicate that they have a claim to represent “a people” within the meaning accorded to that term under the principle of self-determination.  Likewise, in international law, one of the prerogatives accorded to the government is the ability to sanction activity within the territory of a state. It is not clear how military assistance with consent is not a violation of the prohibition of intervention in the internal affairs of a state when the “civil war” threshold is not crossed (even ignoring the difficulties of saying what that threshold actually is), but then becomes a violation of this principle once there is a civil war.

Continued divisions on the subject were apparent when the Institut de Droit International revisited the issue between 2009 and 2011. In his report as rapporteur, Gerhard Hafner raised the possibility that the 1975 resolution did not reflect state practice in the changed political environment of the post-Cold War world, although several members of the IDI disagreed. The IDI resolution adopted in 2011 on the topic of “Military assistance on request”, while “recalling” the 1975 resolution, did not explicitly reiterate its prohibition on military assistance to governments faced with civil war. However, it did state that “[m]ilitary assistance is prohibited when it is exercised in violation of the Charter of the United Nations, of the principles of non-intervention, of equal rights and self-determination of peoples and generally accepted standards of human rights and in particular when its object is to support an established government against its own population.” The 2011 resolution further specified that it was only intended to apply “to situations of internal disturbances and tensions…  below the threshold of international armed conflict as defined in Article 1 of Protocol II Additional to the Geneva Conventions…” This leaves open the possibility that the prohibition on intervention expressed in the 1975 resolution was still envisaged as applying to non‑international armed conflicts within the definition in Additional Protocol II – that is, those between the government of a State and organized armed groups which exercise such control over part of a State’s territory as to enable them to carry out sustained and concerted military operations.

Legal Justifications for Action Against Islamic State in Iraq

The conflict between the Iraqi Government and Islamic State seems to fall within the scope of the prohibition put forward in the 1975 IDI resolution.  At the time the airstrikes commenced  Islamic State exercised control over a significant proportion of Iraqi territory, allowing it enable it to carry out sustained and concerted military operations, and it continues to do so. So if the prohibition on assistance to governments in civil wars only applies to conflicts falling within the definition in Article 1 of Additional Protocol II, that condition would appear to be met in this case. The current conflict seems therefore to provide a useful test case as to whether the prohibition put forward in the IDI resolution is actually part of current international law.

It is therefore significant that States participating in the airstrikes, in legally justifying their actions, have largely relied on a general assertion that military action on a State’s territory with the consent of its government is legal, without any reference to a prohibition of military assistance to governments facing civil wars.  A senior United States administration official in a background briefing given on 8 August 2014 (the day the US operations began) stated that:

“ . . . with respect to international law, we believe that any actions we would take, to include airstrikes, would be consistent with international law, as we have a request from the Government of Iraq.  So we’ve essentially been asked and invited to take these actions by the Government of Iraq, and that provides the international legal basis.”

President Obama’s  notifications to Congress have emphasised that military actions in Iraq “are being undertaken in coordination with and at the request of the Government of Iraq…”.

Likewise, the UK government, in the summary of its legal position published on 25 September 2014, stated that:

“International law is clear that the use of force in international relations is prohibited, subject to limited exceptions. However, international law is equally clear that this prohibition does not apply to the use of military force by one State on the territory of another if the territorial State so requests or consents. It is clear in this case that Iraq has consented to the use of military force to defend itself against ISIL in Iraq.”

It is notable that this summary contained no reference to any prohibition on military assistance to a government in a civil war, despite the UK’s previous endorsement of such a restriction in the 1984 Foreign Office document referred to above. Similarly, the motion passed by the House of Commons to authorize the UK’s participation in the airstrikes on Iraq referred to “the request of the Government of Iraq for international support to defend itself against the threat ISIL poses to Iraq and its citizens, and the clear legal basis this provides for action in Iraq.”

Equally broad assertions as to the legality of the use of force with the consent of the territorial government were made by other participants in the coalition. The French Minister for Defence, speaking in the French Senate on 24 September 2014, justified the legality of French action by stating (my translation): “We act…in conformity with the Charter of the United Nations, for any State can in the exercise of its sovereignty request another State to provide it with assistance.”  The Canadian Foreign Minister, explaining to Parliament the legal justification for Canadian participation in the airstrikes on Islamic State targets in Iraq on 6 October 2014, stated that “[t]he legal authorisation is that the democratically elected Government of Iraq has invited and asked for this support and assistance. The Security Council does not need to authorise it…” Similarly broad statements about the legality of the use of force with consent have been made by the Australian Prime Minister (who said  in an interview on 16 September 2014 that “to operate in Iraq with the support, the consent, the approval, the welcome of the Iraqi government is perfectly, perfectly legal under international law”), and (it appears) by the Dutch government. The generality of these statements about the legality of the consensual use of force, combined with a lack of any reference to a prohibition on military assistance to governments involved in civil wars, seem to count against the existence of such a prohibition as part of contemporary international law.

Is Action Against Islamic State Simply an Application of an Exception to the Alleged Rule?

However, other interpretations are possible. It could be argued that the real reason that the airstrikes are legal, and that their legality has been accepted by most States, is not that there is no prohibition on military assistance to governments in civil wars, but that it falls within one of the asserted exceptions to this rule.

One exception apparently acknowledged in the 1975 IDI resolution and clearly accepted by scholars such as Doswald-Beck, Gray and Corten allows military assistance to the government where the opposition forces in the civil war are themselves receiving external assistance. It could be argued that the intervention against Islamic State falls within this framework, since Islamic State is not a solely Iraqi movement but also controls territory in Syria and recruits fighters internationally. Iraq has referred to the existence of an Islamic State “safe haven” in Syria as a factor necessitating its request for assistance.  Further, in justifying their participation in the airstrikes, foreign leaders have unsurprisingly emphasised that Islamic State threatens not only Iraq but, because of its commitment to terrorism, their own nations. This framing of Islamic State as not simply an internal threat, but a regional and international one, may be interpreted as an attempt to bring the conflict out of the category of a civil war or a purely internal conflict – and thus as an implied recognition of, or at least as not in contradiction to, a general rule that military assistance to governments in such purely internal struggles is prohibited. Considering that Islamic State’s professed aims are not limited to taking over as the government of Iraq, but extend to the establishment of a caliphate which will “break…borders” all over the Middle East, the categorisation of the conflict as something other than a purely internal “civil war” seems plausible.

It has also been suggested by Christakis and Bannelier (also here and in this article in 2004) that, as an exception to the rule which they argue prohibits military assistance to governments in civil wars, military assistance to a government is lawful “when a State assists another during a joint fight against terrorism.” If such an exception does exist then the use of force against Islamic State would fall within it. However, as they themselves admit, “the problem which arises immediately is who can make the decision that a specific group is a terrorist group. Indeed established governments often try to portray their opponents as “terrorists” in order to de-legitimate them politically and be legally able to request external help against them.”

One problem with trying to carve out these exceptions to the supposed rule is that the circumstances indicated by those “exceptions” (and the supporting practice referred to by those scholars who support the supposed rule) seems to refer more to the motivations or reasons for which states provide military assistance to other states, as opposed to the legal justification for intervention. Whenever states take action they will undoubtedly have a policy reason for embarking on such action and will often, particularly in the case of action so serious as the use of force, set out that reason.  However, it would be wrong to think that the motivation or reason equates to the legal justification as that would misunderstand the opinio juris element of custom.

While those states intervening in Iraq against Islamic State refer to it as a terrorist group posing an international threat and perpetrating  atrocities against civilians, these states have in their specifically legal justifications for the use of force generally focussed in broad and unqualified terms on the legality of the use of force with the consent of the territorial State’s government. Therefore, States’ positions on the airstrikes on Islamic State in Iraq do not seem to support the existence of a general prohibition on the use of force at the request of the government in civil wars or internal conflicts.

However, it is also true that there is a trend, as observed by Fox among others, to justify military assistance to governments in terms of the (perceived) legitimacy of the government vis-à-vis its opponents – for example, whether it is democratically elected, or whether it is attempting to fulfil its responsibility to protect its population from atrocities. Although in general, States appear to have kept such legitimacy factors separate from their strictly legal justification of the use of force against Islamic State, there are some instances where these factors are apparently incorporated into the legal argument – for example, the Canadian Foreign Minister’s statement, quoted above, that the request from “the democratically elected government of Iraq” legally justifies Canada’s involvement in the airstrikes. A similar kind of shift may be indicated by the 2011 IDI resolution quoted above, which appears to replace a general prohibition on intervention in civil wars with a more specific prohibition against military assistance “when its object is to support an established government against its own population”. This may potentially make an assessment of the government’s (and the opposition’s) popular support and legitimacy the key factor. Whether these more value‑laden, ‘qualitative’ factors will evolve into an established and coherent rule limiting the general legality of intervention by invitation remains to be seen.

Print Friendly, PDF & Email

Leave a Comment

Comments for this post are closed


Raphaël van Steenberghe says

February 2, 2015

I agree with Th. Christakis and K. Bannelier, who argue for an exception to the prohibition to intervene in civil wars when intervention is only directed against universally recognized terrorist groups. This was well illustrated in the case of Mali: French authorities took care to emphasize that their military operations were not conducted against the Azawad National Liberation Movement (a Tuareg separatist group fighting the Malian forces) but were only aimed at repelling the three Islamist groups occupying the North of Mali. These groups were universally recognized as terrorists (and not as representing any people exercising its right of self-determination).
The legal justifications given by the intervening states in Iraq should not be seen as undermining such a position. It was clear for those states (and some of them like the United Kingdom or Belgium expressly emphasized it) that consent was given by Iraq for the purpose of fighting against the Islamic State (ISIL), an armed group which was universally recognized as terrorist. Their (general) legal justifications and corresponding opinio juris should not be considered too narrowly, i.e. regardless of such context and purpose. In addition, one should not expect politicians to give detailed and comprehensive legal explanations, especially in a press conference or interview. Basically, the Iraqi case may be seen as a relevant precedent confirming the right for states to intervene in the territory of another state at the request of its government in order to fight terrorist groups on its territory.
More fundamentally, I am not sure that the conflict between Iraq and the ISIL before the foreign interventions could be qualified as a civil war in the sense of the 1975 resolution of the Institut de Droit International and, as a result, that the question of an exception to the prohibition to intervene in civil wars is relevant in that case (contrary to the case of Mali).

Dapo Akande says

February 2, 2015

Dear Raphael,

Thank you for your comment. Perhaps I can start with your last comment and ask why you say you are not sure that the conflict between Iraq and ISIL was a civil war, in the sense of the 1975 resolution, prior to the foreign intervention. That conflict clearly seems to be one between the established government of Iraq and an insurgent movement whose aim is to overthrow the government or the political, economic or social order of Iraq and/or to secede or establish self-government. Or do you simply mean you are not sure that it is a purely internal civil war.

With regard to the legal justification advanced by states with respect to their intervention (and support for intervention) in Iraq, you seem to be saying that because states relied on consent to fight Islamic State and because Islamic State is a terrorist group, this means that these states believe that consent of the government is lawful because it is given to fight a terrorist group. However, for that to be right you will need to show that this is indeed the opinio juris or belief of those states. The statements by these states do not seem to indicate that they have such a belief. Certainly the UK statement, that you say emphasises your point, does not seem to indicate any such limitation at all. What the UK government says is that:

"international law is equally clear that this prohibition [of the use of force] does not apply to the use of military force by one State on the territory of another if the territorial State so requests or consents."

No reference is made at all in that particular quote to the nature of the group. Later in that statement, the UK government says that:

"The government is satisfied that the consent of Iraq in these terms provides a clear and unequivocal legal basis for the deployment of UK forces and military assets to take military action to strike ISIL sites and military strongholds in Iraq"

(Emphasis mine),

The terms referred to are the terms of the Iraqi request for assistance. However, when you look at the terms quoted by the UK there is no reference to the terrorist nature of the group.

Finally, it is important to note that the statements we refer to are not just those made by politicians but in the case of the UK was a formal statement(or at least a summary of) of the legal position of a government. In the case of the US we refer to the statement almost certainly of a senior administration lawyer authorised to provide a briefing on the US legal position.

Jordan says

February 2, 2015

Acceptance of the IDI approach would make nonsense out of the U.N. Charter's recognition of the inherent right of collective self-defense. As you note in part, it could also play havoc with self-determination of peoples. Moreover, a simplistic "rule" could play havoc with the effectuation of human rights, long-term peace, and security.
P.S. the U.S. and other states with combatants in Iraq or Syria should recognize that although ISIS is merely an insurgent (with no apparent outside recognition as a "belligerent"), the armed conflict is nonetheless internationalized [so that state armed forces can have combatant status, combatant immunity for lawful acts of war].

Tilman Rodenhäuser says

February 2, 2015

Many thanks Dapo and Zachary for this very interesting post.
I agree with most of your arguments and think it is difficult to assert a rule that prohibits support to governments during NIAC – state practice does simply not seem to conform with the rule.
I do, however, think that the entire question is extremely political which makes strictly legal arguments difficult and less convincing. We seem to assume that assistance can be provided to the party ‘recognized’ as the government. However, I think the question of which party is the government can be a very political, which seems to also put our legal argument in question. F.e., when Seleka took over in the Central African Republic, would it have been lawful to render assistance to the new government in power? If there had not been a SC resolution for NATO intervention in Libya, at what point would it have been lawful to render assistance to the opposition that some recognized as the sole legitimate representative of the Libyan people?
My point is that in a number of cases states may have different views on which party in a NIAC constitutes the government that can lawfully call for assistance. To me, this decision is often taken according to a state’s interests and not so much on legal grounds. The political character of this decision compromises the ‘legal’ character of invoking a rule that allows rendering military assistance following invitation by the existing government.
Would be interested what you think on the issue!

Dapo Akande says

February 3, 2015

Dear Tilman,

Thanks for your comment. You're certainly right that in some civil war cases it can be difficult to know whether an entity that claims to be the government is indeed such. In such a case, there would seem to be good reason to say that consent of "the government" ought not to render the use of force lawful. However, there are many other cases of civil wars where there is little dispute as to which entity is the government. Think of the Biafran civil war in Nigeria in the late 60s/early 70s, or the civil war in Sri Lanka, or even the current situation in Iraq.
To the extent that there might be doubt as to who is the government able to give consent, the reason that consent might be ineffective would seem to follow not so much from the existence of a rule about civil wars but rather simply be an application of the rule that requires consent of the government.

Thanks! Dapo

ELieblich says

February 5, 2015

Dear Dapo,

Thanks for the fascinating post. As you have implied, my own position is that the "civil wars" threshold is obsolete, as it is derived from an anachronistic distinction between "war" and "armed conflict" and from a misunderstanding of the "belligerency" doctrine as applied mainly in the 19th century. Furthermore, it places emphasis on territorial effective control which seems to run counter to current understandings of sovereignty. Moreover, I haven't found, actually, a convincing case where state practice supported such a rule.
Thus the standard that I suggest is the "potential for effective protection of civilians" as a condition for consent power and its negation. This standard can explain why it seems we are comfortable with the actions against ISIS/ISIL in Iraq regardless of the loss of the Government's territorial effectiveness. Simply put, the Iraqi government, on its face, seems to be more conducive to protect civilians than its adversary (and this is an understatement).
Now the interesting question is whether one can justify the strikes in Syria as receiving the tacit consent of Bashar Assad. In practice I think this is happening, but the coalition will not admit this for obvious reasons.


Brad Roth says

February 6, 2015

Thanks to you all for an engaging discussion. A unifying theory of the relationship between international and domestic authority sheds some light on the issue of assistance to governments in civil wars, and reinforces some of the observations offered by Akande & Vermeer, as well as by Lieblich and Fox.

The heyday of articulations of the ban on aid to either side in a civil war -- from the 1929 Civil Strife Convention (among Latin American states) to the 1975 IDI resolution and somewhat beyond -- coincided with the heyday of what I have termed the "effective control doctrine": the test of "effective control through internal processes" for determining a putative government's standing to assert rights, incur obligations, exercise powers, and confer immunities on a state's behalf. The effective control doctrine squares with popular sovereignty in a pluralist international legal order that brackets disagreement about the criteria of governmental legitimacy. A government establishes its standing through the manifest acquiescence of a territorial population that is presumed to oppose, above all, foreign intervention. By even the most grudging acquiescence in an outcome attributable to authentically internal struggle, the state's populace has constructively made its choice of representative for the (limited) purpose of exercising its international legal rights.

Dr. Lieblich is right to lament that this proposition, in effect, “condones the view that the fulfilment of self-determination is a corollary of a party’s capability to effectively use violence”; I refer to the norm as a people's right to be ruled by its own thugs and to fight its civil wars in peace." But in an era in which the criteria of legitimacy were sharply contested and intervention was presumed to be predatory -- in cases of civil disorder, above all -- this view was seriously held. One need only to recall the international community's overwhelming support in 1978-79 for "Democratic Kampuchea" against the Vietnamese invaders.

The bar to assistance to governments in civil wars is a corollary to this principle. If the government needs foreign forces to maintain its grip on power as against a highly efficacious and authentically internal armed opposition, it has failed to secure through internal means the acquiescence that grounds its international standing.

However, as Professors Akande and Vermeer point out, this doctrine accommodates assistance to the government where the opposition's efficacious challenge is owing to unlawful foreign assistance. And in the most cases, efficacy of an armed challenge to an existing government will -- at least, plausibly -- depend on just this, especially because at all points prior to the opposition's challenge being sufficiently efficacious to amount to "civil war," external assistance to the government will have been lawful.

Thus, even in its original form, the norm is largely self-defeating in practice. It comes as no surprise, then, that little evidence for its existence can be found in actual practice.

But beyond this, the picture changes as soon as "effective control through internal processes" -- or, more colorfully, "trial by ordeal" -- is no longer the exclusive determinant of a government's international legal standing. Although I continue to insist that claims about the role of "democracy" in this determination are exaggerated, manifestations of popular support for relatively (and on rare occasion, totally) inefficacious governments -- as evidenced by events including, but not limited to, unambiguous electoral mandates -- can justify support for the government side in a civil war. Moreover, even where the semi-efficacious government has no such mandate (as in the case of Mali's coup regime in 2012-13), the opposition forces may bear characteristics that cause them to be perceived, in common virtually throughout the international community, as repudiated by the territorial population.

The above explanation, roundabout and counterintuitive though it may be, "squares the circle." Despite a residual legal norm to the contrary, assistance to governments in civil wars ends up being lawful in most of the instances where it is being advocated.

olivier corten says

February 7, 2015

Thanks for this stimulating analysis. However, I was surprised you did not mention some crucial documents that provide decisive elements to determine the opinio juris of the intervening States. On 23 September 2014, the US sent a letter to the UN, stating that:

'ISIL and other terrorist groups in Syria are a threat not only to Iraq, but also to many other countries, including the United States and our partners in the region and beyond. States must be able to defend themselves, in accordance with the inherent right of individual and collective self-defence, as reflected in Article 51 of the Charter of the United Nations, when, as is the case here, the government of the State where the threat is located is unwilling or unable to prevent the use of its territory for such attacks' (S/2014/695, 23 September 2014).

On 25 November 2014, the UK sent a letter to the Secretary General and the Security Council 'in accordance with Article 51 of the UN Charter … in response to the request by the Government of Iraq for assistance in confronting the attack by the Islamic State in Iraq and the Levant (ISIL) on Iraq, contained in its letter to the President of the Security Council of 20 September 2014' (S/2014/851, 26 November 2014).

In that letter, the Iraqi Government stated that:

'ISIL has established a safe haven outside Iraq’s borders that is a direct threat to the security of our people and territory. By establishing this safe haven, ISIL has secured for itself the ability to train for, plan, finance and carry out terrorist operations across our borders. The presence of this safe haven has made our borders impossible to defend and exposed our citizens to the threat of terrorist attacks.
It is for these reasons that we, in accordance with international law […] have requested the United States of America to lead international efforts to strike ISIL sites and military strongholds, with our express consent. The aim of such strikes is to end the constant threat to Iraq, protect Iraq’s citizens and, ultimately, arm Iraqi forces and enable them to regain control of Iraq’s borders' (S/2014/691, 22 September 2014).

Another Iraqi letter was invoked by the US and the UK to justify the military intervention, a letter dated 25 June 2014 in which the Iraqi government considered:

'The threat of ISIL is not new to us. Iraq has been subjected to terrorist attacks for nearly a decade by Al-Qaida, which has renamed itself ISIL. The situation has become more serious over the past two years, as ISIL has repeatedly launched attacks against Iraqi territory from eastern Syria […]. At this critical juncture, we are facing a serious threat from international terrorist organizations. We therefore request urgent assistance from the international community' (S/2014/440, 25 June 2014).

Against this background, it is clear that the main argument used by the US and the UK (but also by the Iraqi Government itself) is NOT a possibility to intervene within a 'civil war' at the single request of a government. Article 51 of the UN Charter is expressly invoked, against an 'international terrorist organization' (and possibly against the Syrian State too, if we read some other excerpts of the texts or declarations previously mentioned). The international and terrorist characteristics of the ISIL are similarly denounced in other declarations of the US, the UK, Iraq and many other States (see e.g. S/PV.7271, 19 September 2014 or S/7272, 24 September 2014). A contrario, no State considers the situation could be reduced to a 'civil war' or a 'non international armed conflict'. And, consequently, no State contends that the military intervention should be qualified as a military support to a government combatting a purely internal rebellion. Actually, this is not surprising at all. I know no precedent (at least in the last 6 decades) in which a State would have assumed a legal possibility to help a government to win a purely internal war. The government that calls for help, and the foreign States which possibly intervene, generally contend that the rebels are supported from abroad. In other cases, they evoke a 'peacekeeping operation', or a limited operation aiming at restoring order. But they never assume an unlimited legal possibility to intervene in a civil strife, even at the request of the government. This is why the 1975 (Wiesbaden) but also the 2011 (Rhodes) IDI resolutions are in conformity with a persistant practice, even if some precedents are perhaps difficult to interpret, like the ambiguous operation led by Saoudi Arabia in Bahrain in 2011.

Finally, I perfectly agree with you that this aspect of jus contra bellum (intervention by invitation) is a particularly sensitive one. This can explain the division of the existing scholarship you mention in your post. But, in the present case, the express invocation of Article 51 of the Charter leaves little or no doubt : the intervening States, as Iraq itself, do not quality the situation as a classical civil war. Accordingly, the legal debate should rather, in my view, focus on the admissibility of the (collective or individual) self-defense argument.

ELieblich says

February 7, 2015

Prof. Corten,

It is definitely true that states usually invoke multiple justifications when intervening in internal conflicts, but I'm not sure this is sufficient in itself to negate consent power even if invoked alone. This tendency for multiple justifications might be rooted in legitimacy considerations since "consent" in itself seems like an empty vessel in terms of political discourse. In other words, if you want to convince your public that you should go to war on foreign soil, the fact that a government invited you probably won't score you a lot of points.
In any case, I think that there is also real "legal" motivation to invoke consent in addition to self-defense: this is since in most cases self-defense justifications can only take us so far, due to jus ad bellum proportionality and necessity requirements. Government consent on the other hand, can theoretically allow much more. This is less relevant for Iraq-Syria-ISIS but think of scenarios where initial Article 51 operations were transformed rather quickly to consent-based COIN operations, which of course allowed the intervener way more leeway than the original justification.