Critically assess the limitations of ‘self-defence’ in International

Critically assess the limitations of
‘self-defence’ in International conflict, with reference to the influence of
non-state actors

Following the terrorist attacks in The
United States on September 11 2001, there was an increased demand for the
necessity of a state to be able to use force in an act of self-defence when
faced with acts of aggression. However, some states were considered to be more
interested in the use of pre-emptive force than merely acting in self-defence
of threats. This raises the question: how is it possible to distinguish between
pre-emptive use of force and self-defence? Under international law, the use of
force should be in response to an armed attack, this is defined as “Action
by regular State armed forces across an international border”1
or “Armed groups, irregular forces and mercenaries”2 This is relevant when establishing the
limitations of self-defence in international conflict as it outlines there are
only specific types of attack that warrant acts of self-defence to be carried out
by a state. This can prove to be both beneficial and a hindrance, subject to
interpretation. Whilst having a set definition for the requirements to allow an
act to be carried in self-defence is beneficial as it allows those who act
claiming self-defence without legitimacy to be held accountable, it can be
perceived as a hindrance if an armed attack does not fit the requirements
established in the definition.

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There are number of international
legislative guidelines towards the use of self-defence in conflict such as Article
51 under the United Nations Charter and The UN Security Council Resolution 1368
on the situation in Afghanistan3.
Resolution 1368 was adopted on the 12th September 2001, just one day
after the Twin Towers attack. The Resolution outlined the right of a state to
self-defence when the victim of an armed attack. This reiterated the position
of the United Nations as expressed in Article 514.
When considering the Resolution with regard to the limitations of self-defence,
it is possible to argue that the Resolution sought to stop the United States reacting
to the attacks with disproportionate force. Additionally, it can be argued that
the Resolution look to postpone the United States from responding to the attack
with unjustifiable force towards another state as at the time the resolution
was passed those responsible for the attacks were unknown.5  

This essay will evaluate the
difference between self-defence and the use of pre-emptive force in conflicts. Whilst
pre-emptive force is not typically regarded as an acceptable use of force in
international conflict, it is necessary to question whether this is becoming a
redundant concept. In recent years there has been an increase in attacks
carried out by non-state actors, such as Islamic State. This throws into
question the relevancy of current legislative approaches monitoring
self-defence in international law, and whether there needs to be a change
towards a more pre-emptive method of attack carried out in international
conflict. However, it can be argued that allowing states a use of force
encourages abuse of the system for the gain of the individual state. Natasja
Duhem claims: “Many states have routinely called in their right to self-defence
as justification for their use of force in the war on terror.”6 Consequently,
it is necessary to evaluate a number of other factors, such as the methods of
regulation for use of force, prior to establishing a conclusion towards the
best use of force by a state in the current climate.

The purpose of this essay is to critically
assess the current approach to self-defence in conflict in international law,
both through its legislative approaches and the attitudes of international
bodies such as the International Court of Justice. This essay will analyse the
engagement of states in the use of force both in self-defence and in
pre-emptive attacks, whilst evaluating the influence of non-state actors on the
attitudes of states. Finally, this essay will conclude by assessing the
limitations of self-defence in International conflict.


In order to understand the current
international response to the use of force through both self-defence and
pre-emptive action, it is necessary to establish the legal grounding for
current legislation. At the end of the First World War, the League of Nations7 was
created through the Versailles Peace Conference8.
Under Article 10 of the League of Nations, it was intended that member states
were “to respect and preserve as against external aggression the territorial
integrity and existing political independence of all members of the League”9. At
its height, the League of Nations had 58 member states. However, a number of
factors contributed to its failure to prevent conflict prior to the Second
World War. For example, the Leagues’ failure to include states such as the
Soviet Union owing to its status as a Communist regime, combined with the
unwillingness of its member states to provide force for the League meant that
was not possible for the League of Nations to adequately police the use of
aggression and force.10
Subsequently, this resulted in a lack of confidence in the organisation. Consequently,
the League of Nations can be seen to have collapsed pre-WW2, with its
subsequent disbandment in 1946. However, despite its disbandment, the legislation
established in their precedent was carried forward. For example, Article 2 of
the League of Nations stated that members agreed “in no case to resort to war”11 analyse However, Article 2
of the League of Nations was never instigated, therefore, the agreement to not
resort to war only came into effect in 1928 through the creation of the
Kellogg-Briand Pact12. Whilst
the League of Nations did not adequately address the concept of self-defence,
it did provide a structure through which international forces were able to
overlook the use of force internationally across states.

The Kellogg-Briand Pact was introduced
in 1928. As previously mentioned, the Pact contained some shared concepts with
the League of Nations. Article 1 of the Pact demands member states:  “condemn recourse to war for the solution of
international controversies, and renounce it as an instrument of national
policy in their relations with one another”13.
The purpose of this, as explained by Humphrey Waldock was “to forbid all
unilateral resort to war for purely national objects whether on just or unjust grounds but to permit war as a collective
sanction either under the Covenant or the Pact itself”14 explain

law progressed from jus ad bellum to jus contra bellum”15

During the creation of the treaty, it
was stated that: “Nothing in the new treaty restrains or compromises in any
manner whatsoever the right to self-defence. Each nation in this respect will
always remain free to defend its territory against attack of invasion”16 By
allowing some degree of freedom to States to defend their own territory through
self-defence, it reduces the strain on the Security Council to oversee all
procedures carried out by States. In turn, this allows greater focus to be had
on issues elsewhere, such as instances where this freedom is abused.  Conversely, by not providing any statutory
limitations to the action taken under self-defence, the Kellogg-Briand Pact did
not provide a standard for acceptable limit of force used through self-defence,
whether to be considered proportionate or legal. Subsequently, the use of
self-defence by States can be considered

The end of the Second World War saw
the creation of the United Nations Security Charter. Under chapter 7 of the
Charter, Articles 39 and 24. explore
The introduction of both the League of Nations and the United Nations Charter
mark a significant moment when assessing the use of self-defence in
International Law as they mark the first legislative guidelines provided on the
topic in international law.

Article 51

Article 51 first states the United
Nations’ position on acts of self-defence prior to any action having been taken
by a country: “Nothing in the present Charter shall impair the inherent right
of individual or collective self-defence if an armed attack occurs against a
Member of the United Nations, until the Security Council has taken measures
necessary to maintain international peace and security.”17
When this is given greater scrutiny, the “inherent right” of the member states
demonstrates the acknowledgement of the individual states’ right to defend
themselves against armed attacks. However, it is also clear in specifying the
actions taken by the state are in response to an armed attack that has
occurred. Subsequently, it is possible to establish that Article 51 does not
recognise pre-emptive use of force as a measure of self-defence to be taken by
United Nation member states.

Security Council

Purpose: Maintain international peace and

Following this, Article 51 outlines
the Security Councils’ response to action taken in self-defence by member
states: “Measures taken by Members in the exercise of this right of
self-defence shall be immediately reported to the Security Council and shall
not in any way affect the authority and responsibility of the Security Council
under the present Charter to take at any time such action as it deems necessary
in order to maintain or restore international peace and security.”18

Immediately reported

Authority of the Security Council

Such action it deems necessary

Purpose: Restoration of peace

Pros/Cons of Article 51

Criticisms of article 51

2002 Bush Doctrine  – no distinction between terrorists and
those who harbour them post 9/11 self defence – proportionality and necessity.


The end of
the Second World War witnessed the introduction of the United Nations Charter19.
Article 2 (4) under the United Nations Charter outlined the prohibition of the
use of force: “the provision in the UN charter prohibits the use of force,
whether it amount to war or not”20
This is significant because it demonstrates the attitude of the United Nations,
showing that violence against another state should not be considered when faced
with conflict unless in an act of self-defence. Therefore, violations of this
article would be demonstrated through a use of force that was not considered
self-defence. The implications of Article 2 (4) were demonstrated through their
violation in the Nicaragua case. United States breached the use of force
under art 2(4)In order to
analyse the use of self-defence in international conflict, it is necessary to
establish the criteria for self-defence to be claimed following a display of
aggressions. The criteria for self-defence are
as follows: the state must be victim to an armed attack, and subsequently declare
itself a victim; the state must request assistance from other state/states if
engaging in collective self-defence. Additionally, the state must (under treaty
law) and preferable (under customary law) report to the Security Council21.
If these requirements are not met, it is possible for the offending state to be
brought before the Security Council. In this instance, The United States were
deemed to have failed to meet the requirements for an act of self-defence.
Firstly, the United States were not victims of an armed attack in this
instance, subsequently they could not declare itself a victim.  Secondly, The U.S. did not have enough
responsibility for intervention despite role in the conflict.

Additionally, there was no request from the involved parties for the U.S
to intervene. “For the United States to be legally responsible, it would have
to be proved that that State had effective control of the operations in the
course of which the alleged violations were committed”22.
Subsequently, the United States can be seen to violate the UN Security Councils’
terms for the claim of self-defence. This is further demonstrated by an unlawful
use of force, as the United States’ response was not proportional to the threat
against it.  

Another reason the United States could not rely on self-defence is as a
consequence of a violation of customary international law. The Declaration
on Principles of International Law Concerning Friendly Relations and
Co-operation among States explains: “every State has the duty
to refrain from organizing or encouraging the organization of irregular forces
and armed bands… for incursion into the territory of another state”23

“The use of force may
not be used to support terrorist acts and civil strife carried out against
other states”24

 U.S. went against customary international law
and Article 2(4) through its use of force and violation of article 51 –
conclusion/ summary – lessons learnt? Impact on non-state actors.


Defence vs Pre-emptive attacks – 182/

It is necessary to analyse the extent
to which self-defence can be used as a justification for the actions of a
state. In some instances, the conduct of a state may be considered a
pre-emptive strike rather than the act of self-defence. Why? However,
pre-emption is not considered in the same regard under international law. For
example, example.
This demonstrates explain.
Therefore, Conclude

Duhem states: “The threat posed by
terrorism today has become much bigger following the immense technological
developments and increasingly globalized environment”25.
An increase in presence of Non State Actors in the international community

Article 2 (4) – Can be used to allow
state actors to tackle NSA’s internally through pre-emptive force but does not
allow for international response

One example of the use of pre-emptive
force was demonstrated by Japan example, explain, conclusion

In other instances, such as (United Kingdom) example,
explain, conclusion

Point to consider – location of
non-state actors – state location where there is no govt to hold accountability
– absurd that “international law prohibits us from capturing terrorists
in international waters or airspace; from attacking them on the soil of other
nations, even for the purpose of rescuing hostages; or from using force against
states that support, train and harbor terrorists or guerrillas”26

 ‘ratione personae.’

Recent events – Prior to 9/11,
few individual terrorist attacks were serious enough to meet the ICJ’s high
threshold for an ‘armed attack27

Conclusion – 500 words
Conclusion – how is pre-emptive attacks different to self-defence, does the law
view them differently? How are they monitored? Pros and Cons – Should
pre-emption be



Resolution 1368 full

Article 51 full title



League of Nations Full

Versailles Peace Conference Full

Article 10 League of Nations full title


Article 2 League of Nations full

The Briand-Kellogg Pact full




French Note, July 14, 1928 in Foreign
Relations 1928 – 1, Supra, Note III.10 at 107-108

Article 51, United Nations Charter full title


United Nations Charter full

B. Simma and others (Eds), The Charter of the United Nations: a Commentary
(Oxford University Press, Oxford, 2012) vol 1, 112. (‘Commentary to the
Charter’); Case Concerning the Military and Paramilitary Activities in and
Against Nicaragua (Nicaragua v United States of America) (Merits) 1986 ICJ Rep
14, paras 188-190 and 228


Nicaragua Case Full Title

Declaration on Principles of International Law Concerning Friendly Relations
and Co-operation among States in Accordance with the Charter of the United
Nations, General Assembly Resolution2625, 25 R.G.S 121,123 (1970)

Para 195


26 G
Shultz, ‘Low Intensity Warfare: The Challenge of Ambiguity’ (1986) 25
International Legal Materials 204

27 file:///C:/Users/anola_000/Downloads/200-1-390-1-10-20120625.pdf