Military Necessity

In times of armed conflict, military necessity is the concept used to justify

the use of armed force. The use of armed force is governed by international
humanitarian law (IHL) also known as the law of armed conflict or the law
of war. IHL governs the conduct of hostilities by limiting the means and
methods of warfare to ensure that military necessity remains bound and
balanced by another fundamental principle, that of humanity, also
enshrined in IHL. The rules of IHL embody a thoughtful balance between
the two fundamental principles of humanity and military necessity. This
balance shall guide the interpretation of those rules (especially for the
principles of distinction, precautions and proportionality). IHL rules are
designed to limit suffering, death, injury and destruction in armed conflict,
especially that which is not directly related to, or excessive in relation to, a
specific military necessity and advantage given that in the midst of warfare,
military operations inevitably cause harm.
Historically, one of the first national codifications of the military can be
found in the Lieber Code adopted in 1863 to regulate the conduct of Union
soldiers during the United State of America civil war. It allowed only the use
of military force justified by “military necessity”, defined as such “measures
which are indispensable for securing the ends of the war, and which are
lawful according to the modern law and usages of war.” (art. 14 of the
Lieber Code). Military necessity is limited by the principle of humanity. The
Lieber Code therefore states in article 16 that: “Military necessity does not
admit of cruelty —that is, the infliction of suffering for the sake of suffering
or for revenge, nor of maiming or wounding except in fight, nor of torture to
extort confessions. It does not admit of the use of poison in any way, nor of
the wanton devastation of a district”. This historical precedent has inspired
the military manuals of other countries and the subsequent codification of
IHL.
The principle of military necessity requires that a party to an armed conflict
may resort only to the means and methods that are necessary to achieve the
legitimate aims of the armed conflict. As explained in the Handbook of
Humanitarian Law in Armed Conflicts and also confirmed by the
International Criminal Tribunal for the former Yugoslavia (ICTY)
( Prosecutor v. Blaškić , Case no. IT-95-14-T, Judgment , 3 March 2000,
para. 157):
“The question of military necessity refers to rules of international
humanitarian law and the principle that a belligerent may apply only that
amount and kind of force necessary to defeat the enemy. The unnecessary
or wanton application of force is therefore prohibited.”
As the Handbook explains, there is no international authoritative definition
of military necessity, even when it stands as an exception to some IHL rules.
However, the relevant literature and jurisprudence agrees on its basic
components: military necessity is an action that is (1) urgent; (2) necessary
to achieve of (3) a known military purpose; and (4) consistent with
international humanitarian law.
Indeed, any violence or destruction that is not justified by military necessity
is prohibited by IHL. The use of armed force is legitimate only in the pursuit
of specific military objectives, and then only as it remains within the limits
of the rule and principle of proportionality. Under the rule of
proportionality, the military necessity is closely linked to the military
advantage expected from an attack. This anticipated military advantage
must be weighed against the expected civilians casualties and damage
resulting from and preceding such an attack.
Conversely, the concept of military necessity can be used to challenge the
use of armed force when it appears that the violence or destruction were:
•unnecessary —the target or victims were not linked to a specific military
objective; •disproportionate —the military advantage was disproportionate
to the collateral damage to civilians;
•indiscriminate —the attack did not distinguish between military targets
and civilian objects; and
•aimed at spreading terror among the civilian population.
Military necessity can neither justify nor authorise acts prohibited by IHL.
Derogating from a rule of IHL on the grounds of military necessity is
possible only for those rules which expressly provide for it
(ICRC, Commentary on the Additional Protocols of 8 June 1977 to the
Geneva Conventions of 12 August 1949 , 1987, para. 1389 and Commentary
on the Third Geneva Convention , 2020, para. 497). Military necessity
function both as a fundamental principle and as an exception to primary
rules of protection afforded by IHL. Indeed, military necessity can act as an
exception provided that both conduct and purpose otherwise comply with
the law. For example, some IHL protections for civilians and other
protected persons can be limited by the imperative military necessity
exception but only in cases where its admissibility is explicitly and
deliberately provided for (see GCI, art. 33; GCII, art. 28; GCIII, art. 126;
GCIV, arts. 108 and 143; API, arts. 54(5), 62(1), 67(4) and 71(3); CIHL,
rules 43 and 50).
In instances where breaches of the Geneva Conventions are alleged to
amount to war crimes and/or crimes against humanity, establishing the
absence of any military necessity becomes a requirement for the
prosecution and must be proven. A posteriori , a court may assess the
justifiability of the military necessity of an attack on the basis of the
following evidentiary standard enunciated by the ICTY: “Whether a military
advantage can be achieved must be decided […] from the perspective of the
‘person contemplating the attack, including the information available to the
latter, that the object is being used to make an effective contribution to
military action.’ In other words, each case must be determined on its facts.”
( Prosecutor v. Strugar , Case no. IT-01-42-T, Judgment , 31 January 2005,
para. 295; Prosecutor v. Galić , Case no. IT-98-29-T, Judgment , 5 December
2003, para. 51).
Military necessity does not stand in isolation from other rules and principles
of IHL. It must always be articulated with rules relating to the means and
methods of warfare, military objectives, attacks, proportionality and the
protection of civilians. In other words, the assertion of military necessity is
not sufficient to justify an attack, or any coercive action not expressly
prohibited by IHL. Commentaries to the Additional protocols to the Geneva
Conventions have clarified that the absence of an express prohibition in IHL
for a particular military practice does not mean that it is permissible
(ICRC, Commentary on the Additional Protocols of 8 June 1977 to the
Geneva Conventions of 12 August 1949 , Article 35 of API, 1987, para. 1395
and Commentary on the Third Geneva Convention , 2020, para. 497).
This is particularly important to ensure that rapidly evolving military
practices and weapons remains within the bounds of IHL. This is notably
the case in a number of challenging situations, including cyber warfare,
cluster munitions and urban warfare, targeted killing, etc.
It is also important to ensure respect of IHL in specific contexts of armed
conflict, in particular wars against designated terrorist groups, where the
argument of national security is used in addition to military necessity to
invoke derogations from IHL and the rule of law.
Jurisprudence
Military necessity is referred to and debated in various judgments
of international courts ranging from the Nuremberg military special
tribunal to the international court of justice (ICJ), The International
Criminal Court (ICC), the Extraordinary Chambers in the Courts of
Cambodia (ECCC) and the European Court of Human Rights
(ECHR).