Article 51 of the UN Charter

Self-defence: Article 51 of the UN Charter
Present law: using force in self-defence
• Despite the prohibition on the use of force in Article 2(4),
states may use force in self-defence under Article 51
Frequently, when states use force they attempt to justify it
under Article 51
Article 51 is a very important part of the Charter
It comes within Chapter VII of the UN Charter
Let’s look at Chapter VII briefly before analysing Article 51
in particular
Chapter VII of the UN Charter
• To download Chapter VII, click here:
Chapter VII contains Articles 39-51
Chapter VII deals with threats to the peace, breaches of
the peace and acts of aggression
Chapter VII states that the Security Council will decide if
there has been a threat to the peace, breach of the peace
or act of aggression
It is the Security Council that will decide on what
measures must be taken to restore international peace
and security
Article 51 comes at the end of Chapter VII
Article 51
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. 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.
What does Article 51 mean?
• If a state suffers an ‘armed attack’, then it may respond
• The state doesn’t have to ask for permission to use force
• This is logical: waiting until it goes before the Security Council
could take time
• A state has that right ‘until the Security Council has taken
measures necessary to maintain international peace and
• The state that uses force in this way must notify the
Security Council immediately
• Even if a state uses force under Article 51, the Security
Council can still take any action that it deems necessary
What does “inherent right” mean?
• ‘Inherent’ means “existing in something as a permanent,
essential or inseparable element or quality”
In Article 51, it means that all states have the right to use force
in self-defence, and that this right is part of being a state
The right of self-defence predates the UN Charter
It was part of customary international law - the right already
existed when the UN Charter was signed
Remember the Kellogg-Briand Pact 1928 – many states signed
but reserved the right to use force in self-defence
When read with the words “Nothing in the present Charter shall
impair the inherent right of…self-defence” it confirms that
states already had the right to use force in self-defence and
that the right continues, even after the UN Charter
The Caroline case - I
• The traditional definition of self-defence
comes from the Caroline case
• “it was in the Caroline case that self-defense was changed
from a political excuse to a legal doctrine”
• R Y Jennings, “The Caroline and McLeod cases’ 32 American Journal of
International Law, 1938, p.82
• The facts:
• The Caroline was a boat
• It was being used by some Canadian rebels, fighting against British
rule in Canada
• Americans were helping the rebels using the Caroline
• Members of the British Navy set the boat alight and sent it over the
Niagra Falls (an American was also killed)
• It became a major diplomatic incident between the US and the UK.
The Caroline case - II
• There was correspondence (letters) between the US and
• The letters that were exchanged between US Secretary of
State Webster and Lord Ashburton from the UK contained
several statements on the use of force in self-defence
• Those statements have been accepted over the years
and have become part of the customary international law
of self-defence
The Caroline case – III
The principles agreed upon
• To use force there must first exist:
• “a necessity of self-defence, instant, overwhelming, leaving no
choice of means and no moment for deliberation”
• Any action then taken:
• “must not be unreasonable or excessive since the act, justified by
the necessity of self-defence, must be limited by that necessity and
kept clearly within it”
So, how should Article 51 be interpreted?
• Two main schools of thought:
Some scholars say that Article 51 and Art 2(4) are
exhaustive - that means, the right to self-defence is
now described in the UN Charter, and ONLY in the UN
2. Other scholars say that there is a customary right and
there is also a right under Article 51 (they use the words
“inherent right of self-defence” to argue that a right
already existed before the Charter and it still exists)
How do we resolve this conflict?
• We should turn to the International Court of Justice (ICJ) –
it is the body that interprets and applies international law
• The ICJ has stated that
• The words “inherent right of self-defence” refers to a right in
customary international law that existed before the UN Charter
came into existence
• Article 51 does not “subsume and supervene” customary
international law
• The ICJ made these findings in a famous case called the
Nicaragua case
The Nicaragua case
• Full name:
• Case Concerning Military and Para-Military Activities In and Against
Nicaragua (Nicaragua v United States of America), (Merits),
Judgment of 27 June 1986, ICJ Reports, 1986.
• The judgment is available here:
A summary is available on wikipedia by clicking here:
• What was that case about?
The Nicaragua case: the facts
• Nicaragua brought a case to the ICJ against the USA
• Nicaragua claimed that the US had been recruiting,
training, arming, equipping, financing, supplying and
otherwise encouraging, supporting, aiding, and directing
military and paramilitary actions in and against Nicaragua
(the US was supporting the ‘contras’ who aimed to
overthrow the government)
• Nicaragua also claimed that the US had (inter alia) :
• Breached Artice 2(4) of the UN Charter;
• Breached the Treaty of Friendship, Commerce and Navigation
between the Parties signed at Managua on 21 January 1956
• Violated Nicaragua’s sovereignty by attacking by air, land and sea,
killing Nicaraguan citizens, mining its harbours
• Used force and the threat of force against Nicaragua
The Nicaragua case: what Nicaragua
• Nicaragua went to the ICJ seeking:
• A halt to the US’ activities in funding the Contras
• A halt to the US interference in Nicargua
• Compensation - Nicaragua wanted reparations from the
US to compensate for the damage caused to its people,
property and economy, for breaching the UN Charter and
for breaching a treaty between the two countries
The Nicaragua case: The judgment
• There was initially argument as to whether the ICJ had
jurisdiction to hear the case
Nicaragua won that argument – the ICJ found that it had
jurisdiction – the US then withdrew from the ICJ altogether
Then the ‘merits’ of the case were heard
The ICJ found (inter alia) that:
the United States had been involved in the "unlawful use of
The alleged violations included attacks on Nicaraguan facilities
and naval vessels, the mining of Nicaraguan ports, the invasion
of Nicaraguan air space, and the training, arming, equipping,
financing and supplying of forces (the "Contras") and seeking
to overthrow Nicaragua's Sandinista government.
This was followed by the statements that the judges voted on
The Nicaragua case: what happened in
the end?
• Nicaragua won
• The ICJ held that the US had acted unlawfully and should pay
• But the US refused to comply with the judgment
• Nicaragua tried many times to get the US to comply: the US refused
• Nicaragua brought the matter to the Security Council many times:
In 1984 (once)
In 1985 (three times)
In 1986 (twice)
Every time, the US used its veto power (See notes for source)
Nicaragua also took its case to the UN General Assembly in 1987 seeking the
US’ compliance: the US and Isreal were the only countries that voted against
that resolution
The US never took any notice of the ICJ’s decision
The US never paid compensation to Nicaragua
The US never apolgised to Nicaragua for its actions
Why is this case important?
• For many reasons…
• Regarding jurisdiction
• Regarding the fact that the US completely ignored the
• Regarding the meaning of Article 51
• that the right of self-defence is contained in both Art 51 AND
customary international law
• That the rules in Art 51 and customary international law overlap but
are not exactly the same
• For stating that an ‘armed attack’ can occur by a state or by nonestate actors: ‘the sending, by or behalf of a state of armed bands or
groups which carry out acts which are of such gravity that they
would amount to an actual armed attack conducted by the regular
armed forces…”

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