Isabella Wong. Journal on the Use of Force and International Law. Volume 6, Issue 1, 2019.
1. Introduction
States often justify their foreign military intervention in another state’s internal conflict on the basis of the latter’s consent. Current examples of alleged ‘intervention by invitation’ include the United States-led airstrikes against Daesh in Iraq and the Russian and Iranian interventions in Syria. However, while intervention is clearly ‘allowable at the request of the government of a State’, analysis of the legal framework by which consent may justify a prohibited use of force under Article 2(4) of the United Nations (UN) Charter remains relatively underdeveloped. Accordingly, this article will synthesise existing commentary and contribute to it by analysing consent in the context of two internal conflicts: the Russian intervention in Crimea in 2014 and the Saudi-led intervention in Yemen since 2015. The objective is not to assess whether these interventions strictly comply with the jus ad bellum, as this would effectively be contingent on determining certain unavailable factual elements ‘beyond reasonable doubt’; a matter beyond the scope of this article. Rather, the relevant issues are: first, the contemporary view of the legal framework of intervention by invitation (section 2); secondly, how this view operates in relation to the interventions in Crimea and Yemen (section 3); and thirdly, the significance of these interventions for the legal framework (section 4).
As the key conclusion to be drawn from the discussion in sections 2 and 3, section 4 will contend that the paradoxical interpretation in both state practice and the academic literature of the legality of the interventions, despite an ostensible absence of authority to consent in both conflicts, suggests a departure from the theoretical framework articulated in section 2. Further, section 4 observes an emerging tendency on the part of intervening states to invoke a ‘purposive’ approach and the counter-intervention principle among several alternate legal justifications for their foreign military intervention, leaving the concept of intervention by invitation open to abuse in practice and highlighting the need for a more critical approach toward states purporting to rely on ‘exceptions’ to the prohibition on the use of force under Article 2(4) of the UN Charter.
Given the complexity of these issues, this article does not consider consent in the context of peacekeeping operations; it is strictly constrained to ad hoc consent as it relates to the jus ad bellum.
2. The international law of intervention by invitation
In the exercise of their sovereignty, states frequently consent to foreign military intervention on their territory, ranging from the protection of foreign nationals to peacekeeping and counter-terrorism operations. The academic literature is consistent with state practice in this primary respect: notwithstanding the prohibition on the use of force under Article 2(4) of the UN Charter, foreign military intervention is clearly ‘allowable at the request of the government of a State’ and prohibited at the request of the opposition. The controversy instead centres on the conditions for valid consent; focusing on their application in practice, particularly in circumstances of internal conflict, as well as debates in the academic literature as to their content and interpretation. The following section will examine this controversy in the context of the Russian intervention in Crimea and the Saudi-led intervention in Yemen. The key question for this section is whether, and, if so, on what conditions, consent may in theory constitute a legal justification for a foreign military intervention in an internal conflict that would otherwise be deemed contrary to Article 2(4) of the UN Charter. Prior to this discussion (subsection 2.2), this section will contextualise consent within the law of state responsibility, articulate the conditions for valid consent under general international law, and reconcile the possibility of consenting to foreign military intervention with Article 2(4) of the UN Charter (subsection 2.1).
2.1. Consent in international law
The uncontested principle that a state may validly consent to foreign military intervention stems from the privileging of state sovereignty in contemporary international law, particularly Article 2 of the UN Charter. This perhaps explains why the International Law Commission (ILC) retained consent as a circumstance precluding wrongfulness in its codification of the law of state responsibility, despite the conceptual complexities this has generated with respect to consenting to conduct contrary to peremptory (jus cogens) norms, specifically the prohibition on the use of force under Article 2(4) of the UN Charter (subsection 2.1.1). Nevertheless, the theoretical orientation of consent within the state responsibility framework has provided an opportunity for the ILC to clarify its definition and establish strict conditions for its validity (subsection 2.1.2).
2.1.1. Consent to the use of force in international law
The ILC articulates consent in Article 20 of the Articles on State Responsibility (ASR) as a circumstance precluding wrongfulness of an otherwise unlawful (‘internationally wrongful’) act, provided the consent is valid and the conduct remains within the limits of the consent given. This formulates consent as a secondary rule which assists in determining whether a breach of any primary rule of international law has occurred, such that an exercise of valid consent precludes the occurrence of an otherwise unlawful act and prevents engaging the responsibility of the state from the outset. Furthermore, the ILC observes that the consent of a state merely dispenses with the performance of an obligation owed by another state to it individually, as opposed to displacing the underlying obligation. Accordingly, where a state validly consents to a foreign military intervention, the prohibition on the use of force remains operative as between the two states, but is precluded only on that specific instance and only to the extent to which the consent is given.
The possibility of consenting to a foreign military intervention appears to be inconsistent with a prima facie interpretation of Article 26 ASR, which provides that circumstances precluding wrongfulness do not authorise or excuse any derogation from a peremptory norm of general international law. Presuming the prohibition under Article 2(4) of the UN Charter is an obligation from which no derogation is permitted, Article 26 theoretically means that consent cannot preclude the wrongfulness of a foreign military intervention which is contrary to Article 2(4) of the UN Charter. Article 26 thereby yields a paradox between the peremptory character of the prohibition and the possibility of derogating from it by consent. The ILC highlights this inconsistency, observing that the effect of Article 26 on consent may vary depending on the peremptory norm. Consent cannot preclude the prohibitions on torture and genocide, for example, but a ‘State may validly consent to a foreign military presence … for a lawful purpose’, which suggests that Article 26 does not exclude the relevance of consent to the prohibition on the use of force.
ILC Special Rapporteur, James Crawford, sought to reconcile this paradox by conceptualising consent, or rather its absence, as an intrinsic element of the prohibition under Article 2(4) of the UN Charter. On this view, an exercise of valid consent has the effect of precluding an a priori breach of the prohibition. Given no prohibited force occurs in the first place, it is logically impossible to formulate consent as a circumstance precluding wrongfulness with respect to the prohibition, thus preventing any conflict with Article 26 ASR. Crawford’s reformulation provides a legal framework external to that of state responsibility by which it is possible to consent to a foreign military intervention, to which the ILC almost unanimously agreed. Nevertheless, the ILC’s retention of consent as a circumstance precluding wrongfulness has provided a pragmatic opportunity for discussion about the conditions for its validity, which the ILC sought to reinforce.
2.1.2. Conditions for valid consent
Article 20 ASR provides that consent must be ‘valid’ and the conduct to which it refers must be within its scope and duration. The ILC refers the primary question of whether or not consent has been validly given to general international law, which prescribes four conditions for valid consent.
Valid consent must, first, be ‘clearly established’ and ‘actually expressed by the State rather than merely presumed’. This does not prevent consent from being tacit or implied. Rather, the International Court of Justice (ICJ) in Armed Activities confirmed that consent may be communicated or withdrawn in an informal manner. Nevertheless, this condition must be verified in each particular instance to ensure that consent exists at the time of conduct and has not been withdrawn. Secondly, valid consent must be ‘freely given’; that is, it must be unvitiated by error, fraud, corruption, or coercion of the state or its representative. Thirdly, valid consent must be internationally attributable to the state, which contains two implicit elements: first, the consent must derive from an entity that constitutes the authoritative government of the state under general international law, which will be discussed in subsection 2.2.1; and, secondly, it must derive from an authorised class of persons within that government under the primary rule. The ILC opines that the latter depends on the character and context of the primary rule: for example, only the highest authorities of the state, such as the Prime Minister, President, or government as a whole, may consent to a foreign military intervention. Accordingly, commentators generally agree that the consent of subaltern or local authorities, dissident authorities, or local authorities cannot be considered internationally attributable to the state under this particular primary rule. Fourthly, valid consent must be given in advance of the otherwise prohibited conduct or at the time it is occurring; consent given subsequent to the conduct instead constitutes a form of waiver or acquiescence under Article 45 ASR. Consent to a foreign military intervention must therefore exist at the latest by the time the intervention begins. This condition also stems from the conceptualisation of consent as an intrinsic element of the primary rule, as consent subsequent to the use of force would effectively infringe the prohibition under Article 2(4) of the UN Charter.
Moreover, valid consent operates with respect to a foreign military intervention only to the extent that the intervention remains within the limits of the consent given. The ICJ in Armed Activities affirmed this bounded conceptualisation of consent, observing that the consent of a state to an external presence on its territory does not imply the conference of a valid legal title on the intervening state; rather, it pivots on the exact scope of the consent given.
Accordingly, a state may, pursuant to the strict conditions for valid consent, engage in conduct which would ordinarily be prohibited under a primary rule, including a foreign military intervention contrary to Article 2(4) of the UN Charter. However, there is further debate as to the application of these conditions in internal conflicts.
2.2. Consent to the use of force in an internal conflict
This section considers whether, and, if so, on what conditions, consent may in theory constitute a legal justification for an intervention in an internal conflict. It presupposes that the gravity and intensity of the internal conflict has reached such a threshold that it may be characterised as a civil war or non-international armed conflict, as opposed to a mere internal disturbance or unrest. Two issues inherent to an internal conflict complicate the possibility of consenting to foreign military intervention. First, it is difficult to satisfy the condition that the consent is internationally attributable to the state where one or more groups contests the authority of the in situ government (subsection 2.2.1). Secondly, even assuming this condition is satisfied, there is debate as to whether a foreign military intervention can consist of supporting the in situ government against organised armed groups in an internal conflict (subsection 2.2.2).
2.2.1. Government legitimacy
While the condition that consent must be internationally attributable to the state prescribes that only the highest authorities of a state are authorised to consent to a foreign military intervention under the primary rule, it contains a further requirement that the consent must be given by an entity which constitutes the authoritative government of the state under general international law. Accordingly, consent to otherwise prohibited conduct effectively hinges on the authoritativeness, or ‘legitimacy’, of the inviting government under general international law. This is consistent with the principle, articulated by the ICJ in Nicaragua, that a foreign military intervention is only ‘allowable at the request of the government of a State’ and there is no ‘general right of intervention … in support of an opposition’. The question of whether the entity purporting to exercise consent constitutes the authoritative government of the state is particularly complex in internal conflicts where competing groups claim to embody the authoritative government. Furthermore, while commentators generally agree that an authoritative government must enjoy international recognition and exercise a degree of effective control, there are varying opinions as to how these two criteria operate in practice.
General international law prescribes two interconnected criteria for government legitimacy: first, international recognition refers to the inviting entity’s enjoyment of recognition by the international community of its status as the authoritative government of a state; and, secondly, effectivity refers to that entity’s independent ability to command authority over its territory, which generally comprises some consideration of whether or not it receives popular support. Despite some debate as to the degree of recognition or effectivity required, there is widespread consensus that government legitimacy is contingent on both criteria being satisfied to some extent; therefore, neither is independently sufficient to confer legitimacy on an inviting entity. Corten expresses this in terms of the following example: in an internal conflict where the authority exercising control is not the internationally recognised government, it would seem contrary to the ‘legal logic of existing practice’ if the consent of an internationally recognised government that has lost effective power—or, conversely, an entity that is not the internationally recognised government but nonetheless exercises de facto control—was sufficient to validly consent to foreign military intervention. This is implicit in the conceptualisation by some commentators of the criteria as mutually reinforcing, as opposed to mutually exclusive. Lauterpacht, for example, effectively formulates de facto control as a prerequisite for international recognition in asserting that ‘effectiveness of power, accompanied by a sufficient degree of stability and a reasonable prospect of permanence … is the most frequently followed standard of recognition’. Moreover, Corten argues that, given that a state generally conducts relations with another state through a government which it recognises as representative of the state, international recognition has the effect of conferring on, or reinforcing for, that government a degree of effective power, and thus promoting recognition of that government by other states.
However, other commentators observe a ‘strong presumption’ in international law in favour of the established government regardless of whether or not it maintains effective control, which implies a privileging of the criteria of international recognition over that of effectivity. Doswald-Beck, for example, acknowledges that in ‘normal practice’ states continue to recognise the legitimacy of a government that has lost effective power beyond the time at which it has ceased to exercise de facto control and until a new recognisable authority has obtained effective power. This departure from effectivity in state practice seeks to prevent a state from being deprived of all representation on an international level, which would arise from the mere withdrawal of recognition of a prior legitimate government without the recognition of a new authority.
Nevertheless, such an interpretation is prima facie inconsistent with the proposition, articulated by Corten and supported by several precedents, that international law imposes a duty of abstention on external intervention in the absence of effective authority. This is often referred to as the principle of ‘neutrality’ or ‘negative equality’, which was endorsed by the Independent International Fact-Finding Mission on the Conflict in Georgia in 2009 and is a logical corollary of the principles of non-intervention and self-determination to be discussed subsequently (subsection 2.2.2). The principle of neutrality prescribes that where there is a political power vacuum characterised by widespread doubt as to the identity of the authoritative government, no entity may exercise valid consent, regardless of whether or not the internationally recognised ‘government’ which has lost de facto control continues to represent the state on the international stage. This is consistent with the notion that the entry into diplomatic relations with a ‘government’ merely implies, but does not necessarily amount to, the recognition of an entity’s status as the authoritative government of the state. For example, while more than 30 states recognised the Libyan National Transitional Council as the Libyan ‘government’ in 2011, consistent with the movement in state practice away from the official recognition of governments, this did not equate to recognition of the Council as the authoritative government of the Libyan state. Accordingly, there may be a presumption in favour of the in situ government for the limited political purpose of determining which entity represents the state on an international level, but not for the purpose of determining whether or not that entity constitutes an authoritative government that may validly consent to foreign military intervention under general international law. Thus, consent cannot satisfy the condition that it is internationally attributable to the state unless it has been given by an authoritative government that is both internationally recognised and exercises a degree of effectivity. Even assuming this condition is satisfied, however, controversy remains as to whether the intervention can consist of supporting that authoritative government against organised armed groups in an internal conflict.
2.2.2. Foreign military intervention in support of authorities
Disagreement exists as to whether, and, if so, the extent to which, the principles of non-intervention and self-determination can operate to prohibit intervention by invitation where it consists of supporting the inviting government against organised armed groups in an internal conflict. While some commentators maintain that valid consent renders lawful any foreign military intervention under the jus ad bellum, others contend, more compellingly, that a foreign military intervention in an internal conflict, even on the valid consent of an authoritative government, infringes the principles of non-intervention and self-determination when it is directed toward ‘settling’ that conflict in favour of one side or another, thereby infringing on the political independence of that state. The Institut de Droit International endorses this view to some extent, asserting that military assistance ‘may only be provided upon the request of the requesting State’ and is prohibited ‘when it is exercised in violation of the [UN] Charter … [and] of the principles of non-intervention … and self-determination of peoples’. This subsection will examine the legal basis for this interpretation and consider the principle of counter-intervention as a possible exception.
Foreign military intervention contrary to the principles of non-intervention and self-determination. While the principles of non-intervention and self-determination are closely interconnected, in that they concern the protection of political independence, they operate discretely with respect to consent to foreign military intervention. First, the principle of non-intervention concerns ‘the right of every sovereign State to conduct its affairs without outside interference’, as implicit in the protection of the ‘territorial integrity and political independence’ of states in Article 2(4) of the UN Charter. Anti-interventionist language is consistently reflected in normative General Assembly resolutions including, most notably, the 1970 Friendly Relations Declaration, which—in applying Article 2(4) to internal conflicts—provides that:
[e]very State has the duty to refrain from organizing, instigating, assisting or participating in acts of civil strife or terrorist acts in another State … when the acts referred to in the present paragraph involve a threat or use of force.
In observing that the ‘adoption by States of this text affords an indication of their opinio juris as to customary international law on the question’, the ICJ in Nicaragua and later in Armed Activities confirmed that this provision was declaratory of customary international law. This interpretation thereby entrenches the existence of an obligation in customary international law to not participate or interfere in the civil strife of another state. Given a foreign military intervention clearly constitutes an ‘outside interference’ for the purposes of the principle of non-intervention, it is permissible only to the extent that it is not contrary to this obligation.
Secondly, further to the existence of a right to accede to independence for colonial peoples and those subject to an occupying or racist regime, the academic literature has also construed the principle of self-determination as implying the right for a people that already forms a state, as distinct from the government of a state, to maintain its political independence with regard to third states. This is similarly reflected in the Friendly Relations Declaration, which provides that:
[b]y virtue of the principle of equal rights and self-determination of peoples enshrined in the Charter of the United Nations, all peoples have the right freely to determine, without external interference, their political status.
Parallel to the principle of non-intervention, commentators generally agree that the principle of self-determination poses substantial legal impediments to the possibility of consenting to the use of force. This is underpinned by state practice, which indicates that an intervention to maintain an unpopular government in power contrary to the wish of a majority of its people would be to interfere in the determination of its political status, and thus to deny the people ‘the elementary right of self-determination’. Corten observes that such an intervention would also violate Article 2(4) of the UN Charter, in that it would constitute a use of force ‘in any other manner inconsistent with the Purposes of the United Nations’ (including the protection of the right of people to self-determination). In this respect, Doswald-Beck suggests that while the right to self-determination in principle attaches to the people of a state, it is effectively synonymous with a right to the absence of external interference, thereby strengthening and complementing the principle of non-intervention. Thus, a foreign military intervention in an internal conflict, even on the valid consent of an authoritative government, would infringe both the principles of non-intervention and self-determination to the extent that it interferes with the political independence of that state. Conversely, this implies that an intervention by invitation may be considered lawful provided it does not interfere with the determination of the political status of the inviting state.
Accordingly, some commentators have proposed a purposive approach, whereby an intervention by invitation may be lawful if it is for a purpose other than to ‘settle an exclusively internal political strife in favour of the established government’. In the context of international cooperation, Corten notes that states frequently consent to a foreign military intervention to permit or enable the intervening state to, for example, pursue its own interests (such as protecting its own nationals or attacking its own organised armed groups in the territory of the inviting state), assist in maintaining law and order, or contribute to a multilateral peacekeeping operation conducted by an international collective security organisation. He observes no indication from state practice that an intervention for any of these purposes is unlawful, assuming it does not concern the inviting state’s internal political status. Corten ultimately uses this as evidence of the robustness of the principle of non-intervention: intervening states consistently prefer to claim as a purpose for their intervention a purpose other than to interfere in the political independence of the inviting state, and frequently claim one of the purposes articulated earlier in this subsection. However, Bannelier-Christakis and Christakis, in their analyses of the French intervention in Mali in 2013 and United States-led airstrikes against Daesh in Iraq since 2014, extrapolate Corten’s purposive approach to formulate a principle that the legality of a foreign military intervention is contingent on that intervention being for a purpose other than to infringe on the political status of the inviting state. Further to those articulated earlier in this subsection, they consider other ‘legitimate purposes’ to include liberating hostages, protecting critical infrastructure, fighting transnational crime, and fighting terrorism. Other commentators have since cautiously recognised the existence of this principle. Nußberger, for example, refers to the emergence of a ‘so-called “terrorism exception”’ to the principles of non-intervention and self-determination.
However, two key issues make this principle problematic. The first relates to the divergence in practice between the rhetoric and actions of states, whereby an intervening state seeking to settle an internal conflict in favour of the in situ government may nonetheless formally invoke a ‘legitimate purpose’ to confer a veneer of legality on the intervention. Bannelier-Christakis acknowledges that this is particularly pertinent with respect to ‘fighting terrorism’: it is a common practice of governments in an internal conflict to politically delegitimise the opposition by portraying it as a terrorist group, both to justify a foreign military intervention in favour of the in situ government and to hinder any attempt by the opposition to request external assistance. Moreover, this issue elicits rhetorical debates about the definition of terrorism and who can designate a specific group as a terrorist group.
The second issue relates to the absence in general international law of any rule mandating the consideration of the purpose of the intervention. While a purposive approach offers an ostensible shortcut to assessing legality, the requirement of a ‘legitimate purpose’ is a mere logical implication of the principles of non-intervention and self-determination, and arguably not a requirement based in international law. Accordingly, this article eschews an implied ‘legitimate purpose’ condition and contends that a foreign military intervention in an internal conflict, even on the valid consent of an authoritative government, would be contrary to the principles of non-intervention and self-determination insofar as it interferes with the political independence of the inviting state. Nevertheless, there is widespread agreement that the principle of counter-intervention constitutes an exception to this interpretation.
Foreign military intervention constituting counter-intervention. While the analysis thus far in this article has assumed the existence of an internal conflict in which the opposition is operating autonomously against the authoritative government, it is necessary to consider a further situation whereby, prior to the state consenting to the foreign military intervention, it is evident that the opposition is actively supported by a third state contrary to Article 2(4) of the UN Charter and the principles of non-intervention and self-determination (‘prior intervention’). The involvement of a third state, presuming it amounts to a prohibited threat or use of force against the authoritative government under Article 2(4) of the UN Charter, effectively ‘internationalises’ the internal conflict such that it becomes an international conflict between the inviting state and the third state. In this specific instance, the widely-accepted principle of counter-intervention prescribes that a state may validly consent to a foreign military intervention which would otherwise infringe the principles of non-intervention and self-determination. Some commentators note that the practical application of the principle is constrained to a prior intervention which constitutes a prohibited use of force under Article 2(4) but does not amount to an ‘armed attack’ under Article 51 of the UN Charter, which includes the arming and training of forces. In this limited scenario, it is axiomatic that the authoritative government may request a foreign military intervention because, contrary to infringing the principles of non-intervention and self-determination, that intervention is instead directed toward protecting the political independence of the state against the prior intervention, which appears entirely consistent with the principles and purposes of the UN Charter. Conversely, if the prior intervention is so significant that it may be characterised as an ‘armed attack’, the legal justification for a foreign military intervention falls within the ambit of collective self-defence under Article 51 of the UN Charter, which constitutes an exception to (rather than an intrinsic element of) the prohibition on the use of force. In light of the foregoing analysis, this article contends that the valid consent of a legitimate government may constitute a legal justification for a foreign military intervention in two key instances: first, where it does not interfere with the political independence of the inviting government, and, secondly, where it constitutes a counter-intervention following a prior intervention by a third state in support of the opposition.
3. Intervention by invitation in recent practice
Recent practice contains many examples of states purporting to legally justify their foreign military intervention in another state’s internal conflict on the basis of the latter’s consent, including the French intervention in Mali in 2013, the United States-led airstrikes against Daesh in Iraq since 2014, the Egyptian and United States airstrikes against Daesh in Libya since February 2015 and November 2015 respectively, and the Russian and Iranian interventions in support of the Assad regime in Syria since (at least) September 2015. Nevertheless, in light of a preference on the part of intervening states to invoke a number of alternate legal justifications and a post-September 11 emphasis on the contentious self-defence exception, there are few examples in the academic literature of how the concept of intervention by invitation might be applied to recent practice. More pertinently, there is limited application to internal conflicts where competing groups challenge the authoritativeness, or ‘legitimacy’, of the entity seeking to exercise consent.
Accordingly, this section will examine this question with respect to two contemporary internal conflicts in which the intervening states sought to invoke the consent of an ousted leader who fled to another state: the Russian intervention in Crimea in 2014 and the Saudi-led intervention in Yemen since 2015. Notwithstanding the factual parallels, the international community rejected Russia’s assertion that the invitation was internationally attributable to the Ukrainian and Crimean states, yet acquiesced to the Saudi-led intervention on the assumption that it responded to a valid request by the Yemeni state. A further question remains as to whether the interventions were contrary to the principles of non-intervention and self-determination because they interfered in the political independence of the inviting state. This section will first contextualise the interventions within the internal conflict, the purported consent, and the response of the international community (subsections 3.1.1 and 3.2.1). It will then discuss whether the consent invoked by Russia (subsection 3.1.2) and the Saudi-led coalition (subsection 3.2.2) prima facie complied with the conditions for valid consent, focusing on the requirement that the invitation is internationally attributable to the state. Finally, it will discuss whether the interventions were consistent with the principles of non-intervention and self-determination (subsections 3.1.3 and 3.2.3).
3.1. Russian intervention in Crimea
In March 2014, Russia deployed troops in support of pro-Russian separatists in Crimea. It alluded to a number of legal justifications for its intervention, including self-defence, protection of Russian nationals, self-determination of the people of Crimea, and most pertinently for this article, the consents of ousted Ukrainian President Yanukovych and the new (avowed) state of Crimea. There is general agreement in both the international community and the academic literature that the intervention, in combination with the continued presence of Russian troops at the Russian naval base in Sevastopol, constituted an ‘armed attack’ and thus a prima facie violation of the prohibition on the use of force under Article 2(4) of the UN Charter. This section will be confined to the purported consent to the Russian intervention in Crimea, notwithstanding some suggestion of a further Russian military presence in the southern and eastern regions of Ukraine.
3.1.1. Context to the Russian intervention
The Russian intervention in Crimea occurred amid the divergence in Ukraine between, on the one hand, the western Ukrainian-speaking regions, and, on the other, the eastern Russian-speaking regions and the autonomous Crimean peninsula which remained subject to prevailing Russian influence. The salient facts are as follows: on 22 February 2014, following months of widespread protests and a parliamentary vote to ‘remove … [him] from the post of president of Ukraine’, the elected President Yanukovych fled to Russia and the Ukrainian Parliament established an interim government under unelected Acting President Turchynov. In late February, pro-Russian forces gained control of Crimea. While Ukraine alleged that these forces received assistance from approximately 16,000 Russian troops, Russia denied its military presence on the peninsula and claimed that the forces were comprised only of local self-defence forces. On 1 March, the Russian Duma authorised President Putin’s request to deploy troops ‘in the territory of Ukraine’. On 11 March, the ‘Republic of Crimea and Sevastopol’ declared itself an independent state and was integrated into the Russian Federation on the basis of a referendum held on 16 March. On 18 March, Simferopol (the Crimean capital) and Moscow concluded a bilateral agreement giving effect to the annexation, which Russian troops effectively enforced on the ground by expelling the Ukrainian military. On 27 March, following Russia’s veto of a substantially similar resolution in the UN Security Council, the UN General Assembly passed Resolution 68/262, which determined that the referendum was invalid and thus incapable of forming the basis for any alteration of the status of Crimea or Sevastopol.
As the primary legal basis for its foreign military intervention in Crimea, Russia invoked the purported consent of, first (from 1 March 2014 until the referendum on 16 March 2014), ousted Ukrainian President Yanukovych, and, secondly (post-referendum), the new state of Crimea. It thus relied on the requests of entities that it considered to be the authoritative government of Crimea, which comprised initially of the Ukrainian state and later of the new Crimean state. However, the international community, via the General Assembly, rejected the notion that either purported consent could constitute a legal justification for the Russian intervention.
First, on 3 March 2014, Russia cited a request from Yanukovych dated 1 March 2014 to ‘use the armed forces of the Russian Federation to establish legitimacy, peace, law and order and stability in defence of the people of Ukraine’. This conceptualised Yanukovych as one of the ‘legitimately elected authorities’ of Ukraine on 1 March 2014, despite him having already fled to Russia and been replaced by Acting President Turchynov in late February 2014. Western states dismissed this idea and instead expressed support for Turchynov and the new Ukrainian government, which it deemed ‘legitimate’ and ‘overwhelmingly endorsed by the Ukrainian Parliament’. The United Kingdom, for example, in describing Yanukovych as a ‘former leader who abandoned his office, his capital and his country’, stated that ‘[t]he idea that his pronouncements now convey any legitimacy whatsoever is far-fetched’. Furthermore, many states rejected the proposition that an unconstitutionally overthrown leader may validly consent to a foreign military intervention in international law, regardless of an absence of effective control. Russia’s preference following the referendum on 16 March 2014 to invoke the purported consent of Crimean authorities suggests that Russia itself may have acknowledged that its initial position was not supported by international law.
Secondly, following the referendum, Russia relied on the request of the new ‘Republic of Crimea and Sevastopol’ as a legal basis for its continued presence on the Crimean peninsula. This hinged on the proposition that, presuming the referendum was an ‘expression of the free will of the people of Crimea’, which conferred validity on Crimea’s declaration of independence, it was within Crimea’s sovereign right as an independent state to invite the intervention. In ostensibly seeking to portray Western states as hypocritical, it also reiterated the ICJ’s statement in the Kosovo advisory opinion that there is no general prohibition against unilateral declarations of independence in international law. However, the international community, by way of General Assembly Resolution 68/262, repudiated Crimea’s declaration of independence on the basis that the referendum was invalid and thus incapable of facilitating any alteration in its status. Ukraine and Western states described the Crimean authorities as ‘illegitimate’, ‘self-proclaimed’, and ‘subnational’, therefore rejecting the possibility of such authorities consenting to a foreign military intervention.
While some commentators suggest that political motivations may have underpinned criticism of the Russian intervention—particularly given that many Western states ‘radically condemned’ the intervention without also referring to the unconstitutionality of the political change which ousted Yanukovych and formed the new Ukrainian government—the ‘community of states as a whole’ refused to accept Russia’s extensive interpretations of international law, which suggested that a foreign military intervention is permissible on the sole basis of the consent of a collapsed power or a self-proclaimed government.
3.1.2. Validity of consent
The issue of whether or not consent constitutes a legal justification for the Russian intervention is contingent on the compliance of the purported consents of Yanukovych and the Crimean authorities with the four conditions for valid consent articulated in subsection 2.1.2. The commentary in the international community and the academic literature as to the legality of the Russian intervention primarily centres on the question of whether or not the requests of Yanukovych and the Crimean authorities were internationally attributable to the Ukrainian and Crimean states respectively. Parallel to the response of the international community, this subsection will contend that both requests failed to satisfy this condition under general international law: first, Yanukovych did not represent the authoritative government of the Ukrainian state when he extended the invitation to Russia; and, secondly, Crimea was not an independent state and therefore could not consent to a foreign military intervention. The remaining conditions for valid consent will also be briefly addressed in determining that neither request may constitute a legal justification for the Russian intervention.
Purported consent of Yanukovych. That Yanukovych was neither President, nor in Ukrainian territory, at the time of his request, suggests that he did not satisfy the criteria of international recognition and effectivity. The posture of the international community supports this view: Western states deemed Turchynov and the new Ukrainian government to be ‘legitimate’, and the ‘community of states as a whole’ did not accept Russia’s argument that a deposed President may validly consent. While Yanukovych’s invitation was clearly expressed and seemingly prior to the intervention, it is more difficult to determine on the available facts whether or not it satisfied the remaining conditions for valid consent, which prescribe that the consent is unvitiated and that the intervention is within the scope and duration of the consent. This article maintains that Yanukovych’s purported consent was nonetheless invalid on the basis that it was not internationally attributable to the Ukrainian state, and thus could not constitute a legal justification for the Russian intervention in Crimea.
Purported consent of Crimean authorities. That the international community, by way of General Assembly Resolution 68/262, rejected the validity of Crimea’s declaration of independence implies that the ‘Republic of Crimea and Sevastopol’ did not exist as an independent state, and thus the Crimean authorities could not have validly consented to the Russian intervention on its behalf.
Nevertheless, the purported consent of the Crimean authorities was invalid on a further basis of the principle of ex injuria jus non oritur. The General Assembly, pursuant to Resolution 68/262, called upon states not to recognise, and to refrain from behaving in any way that might be interpreted as recognising, ‘any alteration in the status of the Autonomous Republic of Crimea or of the city of Sevastopol’ on the basis of the Crimean referendum on 16 March 2014. Corten submits that this resolution, as an expression of state practice and opinio juris, supports the existence in general international law of the principle of ex injuria jus non oritur, which prohibits a proclamation of independence and its recognition that directly results from a serious breach of a peremptory norm. Notwithstanding some uncertainty in the academic literature as to the precise legal effect of the maxim, Lagerwall observes that it exists as a ‘principle’ of international law insofar as its logic is reaffirmed by other principles of international law that are more clearly enshrined in treaty and custom; for example, the ICJ in the Wall advisory opinion confirmed an obligation on states not to recognise an unlawful territorial acquisition. Furthermore, the principle of ex injuria jus non oritur is consistent with Article 41(2) ASR, which, according to the ILC, ‘already finds support in international practice and in decisions of [the] ICJ’. Article 41(2) provides that ‘[n]o State shall recognize as lawful a situation created by a serious breach within the meaning of article 40 [i.e. a peremptory norm], nor render aid or assistance in maintaining that situation’. Such situations include an ‘attempted acquisition of sovereignty over territory through the denial of the right of self-determination of peoples’. This article thus presumes the existence of a general ‘principle’ of ex injuria jus non oritur and its relevance to the purported consent of Crimean authorities to the Russian intervention.
While the ICJ determined in the Kosovo advisory opinion that there is no general prohibition against a unilateral declaration of independence, Crimea’s declaration of independence was a direct consequence of the Russian intervention, which was a clear prohibited use of force under Article 2(4) of the UN Charter. In this context, the principle of ex injuria jus non oritur prescribes that states have an obligation not to recognise Crimea’s purported status as an independent state. Notably, Ukraine impliedly referred to this principle in stating that:
[t]he declaration of independence by the Crimean Republic is a direct consequence of the application of the use of force and threats against Ukraine by the Russian Federation … on the basis of customary norms and international law, the international community is obliged not to recognize Crimea as a subject of international law, or any situation, treaty or agreement that may arise or be achieved by that territory.
Corten observes that many states supported this position. Moreover, he submits that Russia did not contest the existence or content of the principle, but rather contested the injuria (illegality) on which it was based: that is, Russia argued that Crimea’s declaration of independence was not illegal in the first place. Thus, the principle indicates that by virtue of Russia’s prohibited intervention in Ukraine, the ‘Republic of Crimea and Sevastopol’ did not exist as an independent state and therefore the Crimean authorities could not have validly consented to the intervention on its behalf. The Crimean authorities instead comprised dissident authorities, the consent of whom cannot be considered attributable to the authoritative government of the Ukrainian state. Furthermore, given the absence of a clearly expressed invitation by the Crimean authorities, the factual uncertainty as to both the invitation and the intervention precludes any determination beyond reasonable doubt of the remaining conditions for valid consent. Accordingly, the purported consent of the Crimean authorities was invalid, such that Russia could not invoke it as a legal justification for its intervention in Crimea.
3.1.3 The principles of non-intervention or self-determination
The purported consents of Yanukovych and the Crimean authorities, even presuming that they complied with the conditions for valid consent, could nevertheless not constitute a legal justification for the Russian intervention because they were fundamentally inconsistent with the principles of non-intervention and self-determination. First, Russia’s deployment of troops to Crimea and its continued military presence at the Russian naval base in Sevastopol clearly involved a prohibited use of force, which violated the obligation under customary international law not to interfere in the civil strife of another state. Secondly, despite Russian efforts to portray the referendum as a manifestation of the right to self-determination of the people of Crimea, the effective control of Russian troops over the referendum amounted to intervention in the determination of the political status of Crimea. Thus, consent could not constitute a legal justification for the Russian intervention in two respects: first, the purported consents of Yanukovych and the Crimean authorities did not satisfy the conditions for valid consent; and, secondly, the intervention was contrary to the principles of non-intervention and self-determination.
3.2. Saudi-led intervention in Yemen
In March 2015, a Saudi-led coalition commenced airstrikes, implemented a naval blockade, and deployed ground troops in Yemen, which prima facie constituted a prohibited use of force under Article 2(4) of the UN Charter. It alluded to two key legal justifications for its intervention: collective self-defence under Article 51 of the UN Charter and the purported consent of ousted President Hadi. While the scope of this article does not extend to self-defence, the present author takes the view that the coalition was unable to rely on collective self-defence due to the uncertainty surrounding the permissibility of self-defence against a non-state actor (i.e. the Houthis). Furthermore, the degree of external (i.e. Iranian) interference in favour of the opposition ‘prima facie appear[ed] insufficient to transform the Houthi [opposition] “aggression” into an armed attack’. This section therefore focuses on Hadi’s request, which, contrary to the Russian intervention in Crimea, the international community primarily accepted as an exercise of valid consent under international law.
3.2.1 Context to the Saudi-led intervention
The Saudi-led coalition intervened in support of Sunni forces loyal to ousted President Hadi in the escalating sectarian conflict with the Zaidi (a variant of Shi’a Islam) population, which was primarily represented by the Houthi rebels that emerged amid the ‘Arab Spring’ of revolutionary protests and violence. On 21 February 2012, then President Saleh agreed to step down and was replaced by then Vice-President Hadi. By September 2014, the Houthis had aligned with forces supportive of Saleh and gained control over a substantial portion of Yemen, including the capital Sana’a. On 21 September, the Hadi government and the Houthis signed the Peace and National Partnership Agreement (PNPA), which conceded to Houthi demands for the formation of a more inclusive government. In February 2015, the Houthis compelled Hadi’s resignation and established a new ‘Revolutionary Council’ government, thus breaching the PNPA. Prior to fleeing to Riyadh, Hadi withdrew his resignation and appealed to the Saudi-led coalition—comprised of Saudi Arabia, the United Arab Emirates, Bahrain, Qatar, and Kuwait—for military assistance. On 26 March, the coalition implemented Operation Decisive Storm (and later Operation Renewal of Hope) against the Houthis, which received military support from Egypt, Morocco, Jordan, and Sudan and the endorsement of the Arab League and Western states including the US, the UK, France, and Canada. On 14 April, the UN Security Council passed Resolution 2216, which reaffirmed its support for Hadi’s legitimacy and expressed concern at the ‘destabilising actions’ taken by the Houthis and Saleh.
On 27 March 2015, concurrent with the launch of Operation Decisive Storm, the Saudi-led coalition invoked as a legal justification for its intervention in Yemen the consent of ousted President Hadi contained in a letter dated 24 March 2015, which requested that the coalition:
… provide immediate support in every form and take the necessary measures, including military intervention, to protect Yemen and its people from the ongoing Houthi aggression … and help Yemen to confront Al-Qaida and Islamic State in Iraq and the Levant.
Moreover, the coalition contended that the invitation extended to ‘confronting terrorist organisations’ and that the Houthis had been ‘supported by regional forces’, later specifying that such support consisted of Iranian interference. This suggests an attempt to mobilise international support for its intervention by engaging two further ideas relevant to consent in general international law: the notion that an intervention for the purpose of ‘fighting terrorism’ may be considered lawful, and the counter-intervention principle.
Contrary to its criticism of the Russian intervention in Crimea, the international community manifested its tacit approval of the Saudi-led intervention in three key respects. First, with the exception of Iran and Russia, it acquiesced to the Saudi-led intervention with limited discussion as to whether or not it was supported by international law. Furthermore, while the Security Council did not any provide ex post facto authorisation for Operation Decisive Storm, it neither explicitly nor implicitly rejected any purported legal justification for the intervention. Secondly, the Security Council did not challenge the coalition’s proposition that Hadi, despite fleeing to Riyadh in the days following his request, remained the authoritative government of the Yemeni state. Thirdly, many states echoed the coalition’s statements as to terrorism and counter-intervention. The Security Council expressed concern about the ability of terrorist organisations, such as Al-Qaida in the Arabian Peninsula (AQAP) and Daesh, to ‘benefit from the deterioration of the political and security situation in Yemen’. Moreover, while the international community did not specifically endorse any allegation of Iranian interference in favour of the Houthis, the Security Council called on member states to ‘refrain from external interference which seeks to foment conflict and instability and instead support the political transition’, and member states generally condemned ‘spoilers’ of Yemen’s political transition. Given that the international community acquiesced to the Saudi-led intervention in these three respects, it appeared to accept the coalition’s reliance on Hadi’s consent.
3.2.2 Validity of consent
The issue of whether consent may constitute a legal justification for the Saudi-led intervention hinges on the compliance of Hadi’s purported consent with the four conditions for valid consent articulated in subsection 2.1.2. As with the Russian intervention in Crimea, the contentious question is whether or not Hadi’s request was internationally attributable to the Yemeni state. Hadi retained little effective control over Yemen as of his request on 24 March 2015: since September 2014, the Houthis had effectively controlled Sana’a, and, in February 2015, they announced the formation of the ‘Revolutionary Council’ government. Nevertheless, Hadi received support from some elements of the armed forces, governorate and tribal authorities, and popular resistance committees, and maintained control over a substantial portion of southern and eastern Yemen, which prevented the Houthis from obtaining de facto control of the entire state. The factual ambiguity as to whether Hadi—or any other entity, including the Houthis—exercised de facto control appears prima facie analogous to an absence of effective authority, in which no entity may validly consent to a foreign military intervention and third states have a duty of abstention. However, the acceptance by the international community of the Saudi-led intervention was inconsistent with this characterisation and therefore yields an ostensible contradiction with this article’s conceptualisation of government legitimacy in international law.
While the explicit acknowledgement by the Security Council of Hadi’s purported consent suggests that it recognised him as the authoritative government of the Yemeni state, by ‘[d]eploring any attempt by the Houthis to take actions that are exclusively within the authority of the legitimate Government of Yemen’ it also implicitly acknowledged that the Houthis were undermining Hadi’s effectiveness. This prompted some commentators to infer a ‘tentative lesson’ that international recognition of an inviting government may effectively ‘compensate’ for an absence of effective control. This is inconsistent with this article’s conceptualisation of government legitimacy in two respects. First, on a theoretical level, this article formulates the criteria of international recognition and effectivity as mutually reinforcing. Secondly, on a practical level, given the prima facie appearance of an absence of effective authority, it logically follows that this article should determine that no entity constituted the authoritative government of the Yemeni state which could validly consent to a foreign military intervention.
However, it would be problematic to assert that a leader whom the international community expressly recognised as representing the authoritative government could not be considered as such due to an inflexible interpretation of the effective control doctrine. This controversy highlights the conceptual difficulties of formulating a threshold at which an absence of effective authority exists, and determining in practice and on the basis of factual elements whether an internal conflict has exceeded that threshold. More pertinently, it ultimately compels this article to reconsider its prior suggestion that there was absence of effective authority. Accordingly, consistent with its conceptualisation of the criteria of international recognition and effectivity as mutually reinforcing, it determines that Hadi’s request was internationally attributable to the Yemeni state and explains his prevailing legitimacy by submitting that the international community’s clear recognition of his government as the authoritative government of the Yemeni state effectively conferred on his government a degree of effective power. Nevertheless, while Hadi’s request was clearly expressed, internationally attributable to the state, and ostensibly prior to the intervention, it is more difficult to determine on the basis of the available facts whether or not it satisfied beyond reasonable doubt the remaining conditions for valid consent, which prescribe that the consent is unvitiated and the intervention is within the scope and duration of the consent. Presuming these are satisfied, Hadi’s purported consent was valid and could constitute a legal justification for the Saudi-led intervention in Yemen.
3.2.3 The principles of non-intervention or self-determination
Assuming the issue of government legitimacy is satisfied, a question remains as to whether the Saudi-led intervention would otherwise be invalid on the basis that it is contrary to the principles of non-intervention and self-determination. This section will contend that Hadi’s purported consent was, in itself, valid but could not constitute a legal justification for the intervention because it prima facie interfered with the political independence of Yemen and thus breached both principles. Nevertheless, in light of the expression by the Saudi-led coalition of its concerns as to terrorism and counter-intervention, it will consider whether a purposive approach or the counter-intervention principle may operate as an exception.
Non-intervention and self-determination. The Saudi-led intervention ostensibly infringed the principles of both non-intervention and self-determination: the airstrikes, naval blockade, and deployment of ground troops clearly constituted a prohibited use of force which interfered with Yemen’s ability to maintain its political independence in relation to third states. However, some commentators suggest that the intervention was directed toward restoring, rather than undermining, the self-determination of the Yemeni people. This presumes that Hadi’s presidency was the legitimate product of an established political transition that was representative of the will of the people and enshrined in political agreements such as the PNPA. Notably, the Security Council expressly supported this by reaffirming Hadi’s legitimacy and calling on ‘all Yemeni parties, in particular the Houthis’, to abide by the agreements which set out the political transition. Nevertheless, Nußberger observes that there is no evidence of any support either in state practice or the academic literature for the existence of a principle that consent may constitute a legal justification for a foreign military intervention where that intervention is directed toward maintaining an established political transition. Conversely, the idea that an intervention could be considered lawful on the basis that it purports to uphold the right of a people to self-determination is fundamentally inconsistent with the right itself: that is, to ‘freely … determine, without external interference, their political status’. Thus, the Saudi-led intervention was contrary to the principles of non-intervention and self-determination and a question remains as to whether or not either a purposive approach or the counter-intervention principle may operate as an exception to this determination.
Purposive approach and counter-intervention. While the counter-intervention principle is generally considered the ‘best established exception to the non-intervention principle’, the notion of an implied ‘legitimate purpose’ condition remains contentious. In the Yemeni conflict, however, arguably neither comprised an exception to the principles of non-intervention and self-determination. First, the Saudi-led coalition’s emphasis on the escalating terrorist threat in Yemen suggests an attempt to engage the idea that a foreign military intervention for the purpose of ‘fighting terrorism’ may be considered lawful. However, even if a ‘so-called “terrorism exception”’ existed in international law, the intervention was predominately directed toward the Houthis, with an ancillary concern about terrorist organisations such as AQAP and Daesh. Thus, while the Saudi-led intervention incorporated a counter-terrorism purpose, it nevertheless ‘took sides’ in the internal conflict and thereby interfered in the political independence of Yemen. Furthermore, this article dismisses an implied ‘legitimate purpose’ condition on the basis that it finds no support in international law.
Secondly, the Saudi-led coalition claimed that prior to Hadi’s invitation, Iran had been cultivating a relationship with the Houthis and providing political and military support to them. However, the substance, if any, of the alleged Iranian interference remains uncertain, at least at the time the Saudi-led coalition commenced its intervention in March 2015. This ambiguity was reflected in the response of the international community: while many states, as well as the Panel of Experts on Yemen, echoed the concerns of the Saudi-led coalition about Iran’s influence in Yemen, they refrained from explicitly reiterating its allegation vis-à-vis Iran. Even presuming that Iran interfered in the manner alleged by the Saudi-led coalition, some commentators argue that the latter could not rely on the principle of counter-intervention because Operation Decisive Storm was ‘clearly excessive’ in relation to the provision of political and military assistance. The Saudi-led coalition therefore could not invoke either a purposive approach or the concept of counter-intervention as an exception to the principles of non-intervention and self-determination. Accordingly, while Hadi’s request was an exercise of valid consent, it could not constitute a legal justification for the Saudi-led intervention because the intervention was contrary to the principles of non-intervention and self-determination.
4. Conclusions
The foregoing analysis of the Russian intervention in Crimea and the Saudi-led intervention in Yemen contends that in neither instance did the consent sought to be relied upon by the intervening states conform to the legal framework of intervention by invitation articulated in section 2. Rather, in both conflicts, the purported consents did not prima facie constitute a legal justification for the foreign military interventions, which implies that both these interventions amounted to a use of force contrary to Article 2(4) of the UN Charter. This conclusion, however, is inconsistent with the more prevalent interpretation of the legality of the interventions in state practice: although both intervening states relied on the request of an ousted leader who by that time retained little effective control, the international community rejected the notion that Yanukovych remained the Ukrainian President yet reaffirmed its support for Hadi’s prevailing legitimacy in Yemen, and largely acquiesced to the Saudi-led intervention. The academic literature reflects this contradictory interpretation, in that some commentators have attempted to explain away the paradox by: first, emphasising factual elements which indicate that Hadi exercised a greater degree of effective control in Yemen relative to Yanukovych in Ukraine; or, secondly, inferring a ‘tentative lesson’ from state practice that in determining whether an entity constitutes the authoritative government of a state, international recognition may effectively counterbalance an absence of effective control.
This second proposition that international recognition may effectively counterbalance an absence of effective control reveals a further inconsistency with respect to the concept of government legitimacy. In its synthesis of existing commentary in section 2, this article preferred a view of the legal framework that conceptualises the criteria of international recognition and effectivity as mutually reinforcing, and considers that no entity may exercise valid consent in an absence of effective authority. Given the factual ambiguity as to whether Yanukovych and Hadi exercised de facto control in Ukraine and Yemen respectively, this view prima facie suggests that both purported consents were invalid on the basis that they did not derive from an entity which constituted the authoritative government of the state under general international law. Rather, no entity in these situations was authorised to consent to foreign military intervention.
However, while this view is reflected in the widespread criticism of Yanukovych’s request, the existence of clear international support for Hadi’s legitimacy fundamentally undermines any assertion that he may not constitute the authoritative government of Yemen. To reconcile this inconsistency with the view of the criteria of international recognition and effectivity as mutually reinforcing, this article reconsidered its analysis of the Yemeni conflict and sought to explain Hadi’s prevailing legitimacy by suggesting that the existence of clear international support had the effect of conferring on his government a degree of effective power.
Moreover, this inconsistency highlights a tendency in the academic literature to construe the legal framework in such a way that aligns with the paradoxical international response to the Crimean and Yemeni conflicts, perhaps to avoid concluding that states do not always comply with international law. Nevertheless, in adhering to a coherent theory of the legal framework, this article posits that a simpler explanation for these inconsistencies lies in the conflicts’ inherent political context, such that it may be the case, as Russia argued, of the international community pursuing a ‘double standard’. This would be symptomatic of a time in which the rule of the law features prominently in states’ rhetoric but arguably has a diminished influence on their behaviour.
In addition to this principal conclusion, three further points can be made. First, a purposive approach to the legality of foreign military intervention appears to be gaining traction in state practice and the academic literature. Intervening states, particularly following the French intervention in Mali in 2013, often claim that their intervention is directed toward ‘fighting terrorism’ or another ‘legitimate purpose’, on the ostensible assumption that this may confer on their intervention a greater sense of legality within the international community. The Saudi-led coalition reiterated that its intervention extended to ‘confronting terrorist organisations’, for which the Security Council expressed support. Furthermore, both sides in the Crimean conflict portrayed the opposition as terrorists: Ukraine condemned the involvement of ‘terrorists … working for the secret service of the Russian Federation’, and Russia alleged that ‘open acts of terror … [were] being committed under the influence of Western countries’. Some commentators discern from this practice an emerging principle that an intervention that is directed toward a purpose other than the determination of the inviting state’s internal political status may be lawful. While this article remains critical of the notion of an implied ‘legitimate purpose’ condition, it nonetheless observes an increasing tendency on the part of intervening states to portray their interventions as directed toward a counter-terrorism purpose.
Secondly, this tendency, coupled with the counter-intervention principle, leaves the concept of intervention by invitation open to abuse in practice. Given an assessment of whether an intervention complies with international law ultimately hinges on determining certain factual elements ‘beyond reasonable doubt’, it is particularly difficult to evaluate whether or not the intervention is in fact for a ‘legitimate purpose’, should such a condition exist, or responsive to a prior intervention by a third state in favour of the opposition. In light of this factual ambiguity, intervening states frequently engage a purposive approach or the counter-intervention principle to confer a veneer of legality on their foreign military intervention. For example, while the international community and some commentators reaffirmed the Saudi-led coalition’s concerns about terrorism and alleged Iranian interference in Yemen, this article has argued that neither an implied ‘legitimate purpose’ condition nor the counter-intervention principle operated as an exception to the principles of non-intervention and self-determination. The vulnerability of the concept of intervention by invitation to misuse reveals a need for the international community to adopt a more critical approach toward intervening states purporting to rely on these ‘exceptions’.
Finally, this article observes an inclination on the part of intervening states cursorily to allude to several alternate legal justifications for their foreign military intervention, rather than formulate one or more robust arguments under international law. Between them, Russia and the Saudi-led coalition’s assertions as to the legality of their respective interventions in Crimea and Yemen referred to notions of consent, self-defence, protection of nationals, self-determination, counter-terrorism, and counter-intervention. Both assertions were problematic. Russia’s reliance on the requests of Yanukovych and the Crimean authorities stemmed from contentious interpretations of international law; and the Saudi-led coalition failed to explain why its concerns about terrorism and alleged Iranian interference supported its reliance on either consent or collective self-defence. Given that consent and self-defence generally involve different factual dynamics, the common practice for intervening states to concurrently invoke these two ‘exceptions’ (noting that consent precludes the occurrence of an otherwise unlawful act from the outset) may highlight the absence of a robust legal justification. However, adopting Corten’s reasoning, that intervening states nonetheless frequently invoke consent as a legal justification—even in relation to such a flagrant violation of international law as was the Russian intervention in Crimea—merely serves to confirm the legal framework of intervention by invitation, and, more broadly, the prohibition on the use of force under Article 2(4) of the UN Charter. Accordingly, while the ostensible absence of authority to consent and the paradoxical international response to the interventions in Crimea and Yemen suggest a departure from this theoretical framework, the question of whether or not an intervening state may invoke consent as a legal basis for its intervention remains relevant within the conceptual parameters of the academic literature, and, more importantly, to contemporary international relations.