L5549 The Use of Force in International Law
1. Critically examine the extent to which military intervention by invitation is
allowed/prohibited in contemporary international law.
Military intervention by invitation denotes “direct military assistance by the sending of
armed forces by one state to another upon the latter’s request” (Visser, “The Legal
Classification of Intervention by Invitation” (2019) 21). This is one of the main exceptions to
the peremptory norm prohibiting the use of force, affirmed in article 2 (4) of the UN Charter,
as its character is non-forcible because of the host state’s consent. Although the legality of
this in principle is universally accepted, there are important caveats surrounding it (Visser,
supra). In this essay, it will first be outlined that despite the wide recognition of military
intervention by invitation, its validity depends upon the free consent of an effective
government. Subsequently, it will be highlighted that there is no strong evidence that such
interventions during civil wars, albeit critiqued for violating the principles of self-
determination and sovereignty, are illegal under international law. Finally, it will be indicated
that the ability of states to consent to military intervention by invitation is restricted, as they
cannot agree to operations, violating jus cogens or actions against the rights of other states,
conducted from its territory, where there is no such necessity.
The legality of military interventions by invitation has been widely recognised in the
international legal system on condition that they are executed following the consent of the
territorial state’s government (Visser, supra). This has been affirmed by the ICJ in paragraph
246 of the Armed Activities case and in article 20 of the ILC’s Draft Articles on State
Responsibility, given they respect the boundaries of the given consent. In order for an
intervention to be valid, it should be given by a government that enjoys effective control of
the state’s territory (UN Doc S/24868 (1992) 3). The ILC further clarified that consent must
be given freely without coercion from the intervening side, as this would disrespect its
sovereignty (Draft Articles on Responsibility of States for Internationally Wrongful Acts with
commentaries (2001), GA Official Records 56th session, supplement no 10 (A/56/10), Art
20, para 6). This would exclude invitations by puppet regimes such as the one in Afghanistan
in 1979, which requested the Soviet Union’s intervention, (Dinstein, War Aggression and
Self-Defence, (2017) 332). However, there are numerous illustrations for state practice, which
was used in a consensual manner and did not face international condemnation, including
France's interventions in Chad, Côte d'Ivoire in 1968 and 2002, respectively, as well as
Senegal's intervention in Guinea-Bissau in 1998 (Gray, International Law and the Use of
Force, (2008) 85). This indicates the lawfulness of interventions by invitation, if the
highlighted conditions are met.
Moreover, there is no explicit prohibition to intervene during a civil war in international
law, should the invitation come from the effective government (Akande et Vermeer, “The
Airstrikes against Islamic State in Iraq and the Alleged Prohibition on Military Assistance to
Governments in Civil Wars”, 2015). This has been perceived as unlawful by certain authors
due to serious risks of violating the right of self-determination, pertaining to the people of the
potential host state, “to choose its own political, economic, social and cultural systems” and
the notion of sovereignty (Gray, supra 81). The extent, to which a government during a civil
war, can be accepted to be representative of the nation-state has also been questioned (Gray,
supra). It is acknowledged that the has affirmed self-determination as an essential principle of
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, international law (East Timor case, para 29). Notwithstanding, in paragraphs 206 and 246 of
the Nicaragua case the ICJ, albeit not explicitly referring to a civil war, confirmed that
intervention upon request of the opposition is prohibited, whilst permissible on the side of the
government. Moreover, paragraph 165 of DRC v. Uganda, the Court affirmed that an
interference in a civil war had occurred. Nonetheless, in paragraphs 42-54 where the Court
discusses consent, it rules that Uganda overstepped the boundaries of the given consent and
its subsequent withdrawal. Thus, the Court seems to accept an intervention by invitation
during a civil war, if the consent is valid. Therefore, it is suggested that a rule prohibiting a
consensual intervention during civil wars, if the invitation comes from the government, does
not exist.
Nevertheless, the ability of states to consent to military interventions is restricted by the
general principles of international law, as they cannot agree to actions on their territory,
violating jus cogens or actions contrary to the right of other states, when there is no such
necessity (Morucci, “Limits to the Use of Force and Questions of Responsibility” (2019) 22).
Article 26 of the Draft Articles on State Responsibility draws upon article 53 of the Vienna
Convention on the Law of Treaties by highlighting that “any act of a state, which is not in
conformity with an obligation arising under a peremptory norm of general international law”
would prevent the applicability of the conditions precluding wrongfulness. Thus, although a
state is entitled to consent to a foreign military presence within its borders, the request must
be aiming to fulfil a lawful objective. Hence, it would be impossible for a state’s consent for
military intervention on its territory to validate another state’s actions, which are violating a
peremptory norm. For instance, committing a genocide or crimes against humanity would be
equally wrongful as in it would in the absence of the invitation of the host state (Morucci,
supra). Moreover, the principle of good faith in foreign relations would also need to be
respected by the territorial state towards other states (Morucci, supra 33). The ICJ has
pronounced that each state has the obligation “not to allow knowingly its territory to be used
for acts contrary to the rights of other states” (Corfu Channel, 1949, 22). This could include
instances of knowingly allowing the intervening side to conduct military operations against
foreign targets, falling beyond the scope of the given consent, for its own economic or
political purposes. Hence, knowingly giving its consent to such operations would be
unlawful.
In conclusion, military intervention by invitation is a lawful method of asking for armed
assistance, as long as consent is given freely by a state’s effective government, including
during civil wars. However, the ability of the host state to consent to the use of force on its
own territory would not preclude the wrongfulness of acts by the intervening state, should
they be violating jus cogens or the rights of other countries, if there is no such necessity.
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