A Comparative Analysis Of Jus ad bellum and Jus in Bello In The Context Of International Humanitarian Law

A Comparative Analysis Of Jus ad bellum and Jus in bello In The Context Of International Humanitarian Law

Author: Akashmika Jena, University Law College, Utkal University, Bhubaneswar


The Law of Armed Force has been customarily theorised in a semblance of prevalent  theories of Jus ad bellumand Jus in bello. Such separate dualist concept of outfitted power and principle of armed force discovers its underlying foundations through the means of legitimate traditions of the happenings of the Interwar period. Besides that, a one on one differentiation regarding the same has been thoroughly highlighted by the means of “Theory of Warfare” The discrepancy between the concepts of Jus ad bellumand Jus in bello has had a prolonged historic convention in connection with the “Theory of Warfare”. Although in scholarly writing, the moralities of the said theories are regularly examined together. Upon retrospection they are as a rule arranged under philosophical, strict or moral belief systems by means of Just War Theory or Just War Doctrine otherwise alluded as Jus bellum lustum. Incidentally they are combined with a third principle specifically Jus Post bellum which incorporates post conflict legal standards.  However, the same earned  its rightful status in the radical law right in the course of the League of Nations.


Acknowledging the principles of Jus ad bellum and Jus in bello in the purview of legal concepts has elicited noteworthy changes in the ways of legal perception as perceived in the 19th century. Nevertheless, the aforesaid concepts not only reformed the acumen of war, but reassured the undiscerning deployment of the onuses concerned with the  belligerent parties  showcasing their demeanour as hostilities. The theories of Jus ad bellum and Jus in bello were heralded by means of distinct standardising creations, in order to propose the decree expressing that all prevailing disputes  be combatted empathetically, independent of the reason of armed violence. The particular article attempts to make a comparative analysis of Jus ad bellum in relation with Jus in bello. The author analyses the concepts of Jus ad bellum and Jus in bello thoroughly with citing relevant articles so as to ensure better understanding of the independent concepts. Lastly, the author provides detailed analysis of “Principle of Proportionality” and “Military Inevitability” under the purview of Jus ad bellum and Jus in bello.

The coveted International Humanitarian Law also alluded to as jus in bello, is the law governing the manners via which war is led. The International Humanitarian Law is temperately altruistic pointing towards restricting a wide range of torment and suffering. The circumstances leading the states to resorting under which States may resort towards or utilization of equipped power is rightfully indicated via Jus ad Bellum. The very standard of International Humanitarian Law is constraining the affliction and anguish brought by war by safeguarding and aiding its casualties by all methods conceivable. The law in this manner uncovers the ground truth of a contention barring the legitimacy behind resorting towards usage of force. The respective law addresses only those issues of  contention of humanitarian concern. Under the UN Charter of 1945, as per Article 2 (4) – “States must avoid the danger or utilization of power against the regional integrity or political independence of another state”[1]. The aforesaid is what is acknowledged and recognised as Jus in bello or Law in War. However the objectives of the charter pertain to the concerned belligerent gatherings regardless of the justifications following the contention and analysing whether the intention behind it is just or not. The restriction against the utilization of power among States and the special cases to it (self-preservation and UN approval for the utilization of power), set out in the 1945 United Charters Act prove to be the core essentials of Jus ad Bellum.  Special cases to this rule are given in the events pertaining to self -defence or owing to the verdict espoused by the UN Security Council mentioned under Section VII of the UN Charter[2]. Jus in bello monitors the demeanour of the concerned parties involved in an armed conflict. International Humanitarian Law is equivalent with jus in bello in the likes of aiming of protecting and aiding  all casualties of an armed conflict to the furthest degree conceivable. Besides that the outcomes of violating Jus ad bellum differ from those in relation with the violations of Jus in bello.  Such distinctions can be highlighted through several instances, firstly Jus in bello in a war of hostility would fail to make a difference in entirety and consequently would tie neither of the concerned parties. Evidently, a summon aimed towards unlimited warfare and conflict subjected to humanitarian and unprejudiced grounds must be shelved. Subsequently Jus in bello only bounds the antagonist completely neglecting the part claiming the plea of self- defence. Nevertheless, the aforesaid suggestion is equally complicated as  subjected to the component of correspondence, the aforesaid is unintelligible that either one of the parties rightfully uphold the principles of the International Humanitarian Law. However the same is exaggerated through the means of debating on the issues assessing one of the party as the assailant given that under similar circumstances each party will without a doubt contend of functioning in self- defence and utterly in accordance with Jus ad bellum. Consequently, the  prerequisite proviso contained in Jus in bello must be in complete distinction from Jus ad bellum, and the same must be considered in an independent manner. Subsequently the Additional Protocol I states that the standards of the coveted International Humanitarian Law ‘must be utilised at all circumstances to all the individuals protected by those secured by those mediums with no unfavourable differentiation dependent on the disposition or inception concerning an armed conflict alongside the grounds espoused by or attributed to the concerned parties’Convention Additional to the Geneva Convention of 12 August 1949(Protocol I), International Legal Materials, The Preamble to the Hague Convention VI [3]states that the protocols are aimed towards limiting the discrepancies arising out of war subjected to military necessities permit’, mirroring the pragmatic methodology received in the codification of the laws of armed conflict. However the same is owed to the grounds stating ‘the two kinds of judgment are coherently autonomous. It is considered completely feasible for an impartial or unjust war to be battled via unfair means or within the purview of the prescribed guidelines. ‘ Hence, the prevailing restrictions on Jus ad bellum has negligible influence on Jus in bello irrespective of operating simultaneously in multiple occasions.

Principle of proportionality under Jus ad bellum

The inevitability of proportionality in the light of Jus ad bellum milieu refrains a state’s capacity to recourse to force, equivalent to the degree of force it can use. Therefore, such power should just be utilized in defence and must be carefully restricted to that cautious objective.

Principle of proportionality under Jus in bello

Surveying proportionality in the light of Jus in bello involves evaluating and assessing the damages and injuries inflicted by an attack against the estimation of the foreseen militarily advantageous position to be accomplished by the belligerent. It depends on the ‘central rule that belligerents abhor a boundless choice of intends to inflict harm on the opponent’.

Application of military inevitability under Jus ad Bellum

The principle Jus ad bellum, authorizes a state to utilize military power in self-defence against an “armed conflict” against it. However, as per the standard International law, the requisite guidelines of necessity holds that force may just be legitimately utilized where it is of utmost inevitability. Now, the principle of Jus ad bellum states that a state may not recourse towards use of armed  depend on equipped power except if it has no other means of action to safeguard itself.

Application of military inevitability under Jus in Bello

As per the rule of military necessity the combatant can demonstrate acts of violence against the adversary military aiming towards defeating the enemy as well bringing an end to the war.

In the case of SAINOVIC et all4]. the following judgement was ruled out “1662. [… ] Whether the retreat to the utilization of power is real under International Law is an issue of Jus ad bellum, which is particular from whether the manner by which that power was utilized was legitimate under International Humanitarian law, for example Jus in bello. The guidelines of International Humanitarian Law don’t require a military commander to abstain from protecting his nation but ensures that he guarantees that his demeanour and that of his subordinates are in compliance with the established humanitarian standards. [… ]”[5][6]


As rightfully elucidated in the article the dangers in associating  Jus ad bellum and Jus in bello are evident, owing to which the differentiation between them has been thoroughly upheld in theory. Moreover, the principal aim of the coveted International Humanitarian Law  is  to secure war casualties alongside their fundamental rights, regardless of the party to which they belong to. Hence, Jus in bello must stay free of Jus ad bellum.

[1] https://www.un.org/securitycouncil/content/purposes-and-principles-un-chapter-i-un-charter

[2] Ibid.


[4] https://cld.irmct.org/assets/filings/Judgement-Sainovic2.pdf

[5] Prosecutor vs. ŠAINOVIĆ et al. Case no. IT-05-87-A (2014)

[6]  See also , Boškoski and Tarčulovski Appeal Judgement, para. 31 ; Kordić and Čerkez Appeal Judgement, para. 812


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