Islamic jus ad bellum: the legitimacy of the use of force by states and armed groups

About the author(s):

Katharine Fortin is an Associate Professor at Utrecht University where she teaches IHL and IHRL. Before joining Utrecht University, she worked at the ICTY, ICC and Norton Rose Fulbright. She is the author of The Accountability of Armed Groups under Human Rights Law (Oxford University Press, 2017) which won the 2018 Lieber Prize. She has written widely about the framework of law that applies to armed groups in non-international armed conflicts and is one of the editors of the Armed Groups and International Law blog.

Today Erik Tristan Zouave joins us again for a guest post on Islamic jus ad bellum and what it says about the legitimacy of the use of force by states and armed groups. Erik (LLM University of York), a former Research Assistant at the Swedish National Defense College International Law Center, has published guest posts with us before on Iraq, Syria and trade in opposition oil (see here and here) and the weaponization of the Fallujah dam (see here).


1. Introduction

In the current context of the protracted non-international armed conflicts and civil strife in Syria and Iraq various actors have increasingly sought to legitimize their conduct through Islamic Law. Notably, the Islamic State of Iraq and Syria (ISIS) the Sunnite armed group involved in the Syrian and Iraqi conflicts have proclaimed their intent to establish an Islamic State, a caliphate, with Abu Bakr, their leader, as Caliph. The declaration was followed by a change in brand simply to the Islamic State (IS).

This begs the questions:

How is collective structure (state v non-state) actually related to the legitimate use of armed violence in Islamic law? What does Islamic law have to say about violence emanating from states as opposed to violence emanating from armed groups? Normatively, what can IS expect to gain from their policy of claiming caliphal authority, or even adopting a jargon of statehood?

While ius ad bellum concepts like just cause/right intent, proper authority and restrictions on the use of force have been limited to intra-state warfare in western traditions, this post will show that Islamic jurisprudence still applies similar concepts in times of intra-Islamic strife. In brief, I will argue that the Caliph may have had considerable historic authority to use force under Islamic law but would still be bound by restrictions both in conflicts outside and inside of the Muslim community. I will further argue that any organizational structure or authority that does not comply with these restrictions of just cause and limited violence may lose its legitimacy to fight under Islamic color and may become a legitimate target for Islamic violence.

2. Islamic jus ad bellum – expansionism and Statehood in an historical context

The Islamic tenets on the legality of warfare developed with the recital of the Quran in the mid -600’s CE, some 1300 years prior to the codification of the ‘Western’ international law instruments regarding ius as bellum.[i] It derives from an era where God was seen to be the ultimate source of legal norms and the religious community (ummah) was central to the law (see here and here).[ii] Islamic law thus retains its directivity, its objective, in upholding and spreading God’s justice and the protection and conservation of the ummah and God’s creation. It follows that the normative conflict between Islamic anthropocentric and expansionist objectives are key factors in the use of force.

In the tribal context of the 600’s, two fundamental challenges were perceived for Islam. One challenge was uniting and pacifying the tribes of mankind within the ummah. The second could be regarded as actually establishing that community as an Islamic community under Islamic legal jurisdiction, restoring mankind to an ummah wahida, a single collective (see here and here).[iii]

The underlying logic of the Islamic law of nations (As-Siyar) is, according to Sheikh Al-Zuhili, the “brotherhood” that is inherent in mankind as God’s creation, the corresponding rights and protection that humans enjoy, and the peace and stability sought in God’s creation.[iv] However, the Islamic system also presupposes God as the one and only source of law, and the supremacy of the Islamic order.[v] The anthropocentric norms of rights and stability have thus classically been at conflict with the Islamic expansionist agenda.

The sources of Islamic law in history

Islamic jurisprudential friction on the matter of international order and statehood is largely due to the historical context of Islam and the ummah wahida which was never achieved. The Islamic sources of law are primarily built on the word of God, as codified in the Quran, the accounts of the life of the prophet as codified in the Sunna/Hadith,[vi] and secondarily interpretive sources such as the scholarly consensus of the Ijma, and the reasoning of diligent Muslims or the Qiyas/Itjihad.[vii] The first two sources evolved in a pre-state setting, spanning, Medinan and caliphal politico-religious unity while much of the interpretive work evolved in the subsequent division of state and religious authority under sultanic rules and post-colonial Islam (see here).

Islam’s relation to the Nation-state

The primary, rigid sources of law could not foresee the creation of the nation-state and the interpretation that later arose out of these primary sources did so in a power competition with western powers. Hashmi, thus notes three schools of interpretation on the relationship between the ummah and the nation-state_

  • the secularists which separate the ummah from any notion of political organization,
  • the reformists which consider the nation-state an acceptable stepping-stone to a higher unity, and
  • the pan-Islamists who consider the nation-state contradictory to the legal principles (or realization) of the ummah.[viii]

It can only be concluded that there is a level of disagreement about the acceptability of statehood in As-Siyar. Nevertheless the Islamic tenants akin to pacta sunt servanda provide an argument for conformity with international standards of sovereignty and preventing unjustified coercive infringement on the political order of states (see here).[ix]

3. Islamic Concepts of Armed Conflict – Expansion and Internal order

The Islamic precepts on the legality of the use of force are often considered to be intertwined with the principles of Jihad yet it is Fitna and Akham al-bughat which regulates intra-Islamic violence (comparable to the Arab Spring or the situations in Iraq and Syria), and the Caliph has traditionally been the legitimate authority behind the use of force (see here).[x]

Caliphal Authority and War

Historically inclined conflict scholars often note on the supremacy of caliphal authority in Islamic ius ad bellum. As suggested by A.R. Murphy and J.T. Johnsson, a conservative interpretation of Islamic tenants and their historical evolution suggest that it was only the imam, the prophet’s successor which possessed legitimate authority to proclaim war.[xi] With the evolution of the Islamic community’s structure, this authority was passed on to the Caliph. This gives the Caliph a position comparable to the Western ius ad bellum conception of just authority.


Jihad is often misunderstood to simply encompass a holy war on non-Muslim communities when it actually embraces varying degrees of force and largely limits the use of force to force outside of the Ummah (see here).[xii] Classically, Islam has perceived itself (and been perceived) to be at conflict with the non-Muslim world, a conflict in which expanding God’s rule is a just cause.

Jihad, meaning struggle, is the obligation for Muslim individuals and communities[xiii] to engage in:

  • A struggle of the heart – a struggle to be free from sin
  • A struggle of the tongue – a struggle to engage non-believers with reasoning and missionaries
  • Armed struggle – the type of Jihad most people are familiar with, the notion of holy war.[xiv]

While the peaceful components of jihad and Islamic expansion have often been overlooked (both by Muslims and non-Muslims), reducing jihad to a right for Muslims to fight non-believers, contemporary scholars often emphasize the defensive nature of jihad. In his article on Islam and International Law, Al-Zuhili, for example cites verses 22:39-40 of the Quran:

To those against whom war is made, permission is given (to fight), because they are wronged, and verily, God is Most Powerful for their aid. (They are) those who have been expelled from their homes in defiance of right, (for no cause) except that they say, ‘Our Lord is God’.[xv]

Additionally, Al-Zuhili posits that that armed struggle of Jihad is further limited by the necessity to precede violence with two choices: conversion or reconciliation with the Islamic community.[xvi]

Fitna & Akham Al-Bughaat

With regard to legitimate intra-Islamic conflict, Islamic legal scholars, such as Aboul-Einein, Zuhur and el-Fadl employ Fitna, insurrection, and Akham al-bughat, the law of insurrections.[xvii] Having developed under caliphal rule, these laws generally affirm the central power (the Caliph).[xviii] However, Kennedy observes that the Islamic rules in general correspond closely to the concepts of “just cause, right intent, proper authority and discrimination in the use of force.”[xix] Notably, it is within the procedural criteria of right authority that disambiguating the legitimacy of statehood becomes crucial. As evidenced by Ko Nakata’s arguments, if statehood is considered contrary to Islam, then states have, by no means, the religious credibility to wage any type of legitimate war, only a caliphate does.[xx] Arguably however, contrary to western practice, the Islamic jurisprudence does not necessarily preclude the applicability of ius ad bellum concepts in situations of non-international armed conflict, or rather intra-Islamic strife.

4. Islamic jus ad bellum & the legitimacy of fighters

Given the normative pull between the expansion of Islamic jurisdiction, retaining peace and stability in the Islamic world and the Islamic rights of man, how can an Islamic view on the legitimacy of intra-Islamic fighters (such as IS) be developed? Briefly stated, there are two sides to consider to this legitimacy.

Firstly, as previously mentioned, the legitimacy of the state authority in times of intra-Islamic strife sits on a precarious and rather ambiguous seat. While Islamic jurisprudence has favored the side of the administrative authority of the Islamic population, proper authority has generally been understood to entail a Caliph. Caliphs have historically taken it upon themselves to chastise Muslim populations whom they believed not to act in conformity with appropriate Islamic norms, and have done so under aegis of their proper authority.  However, it is by no means certain that this privileged legal position can be imputed on a state structure during uprisings or insurgencies.

Secondly, while intra-Islamic strife was probably envisioned to be fully banned and illegal under early Islam, a jurisprudence has developed that provides for uprisings. Muslim scholars agree that, despite the conservatism of the Akham al-bughat, there is no legal obligation to be subjugated to a regime that is not in compliance with Islamic law (see here and here).[xxi]  Hence, the traditional Islamic limitations on the notion of proper authority can be contested in an intra-Islamic conflict.

While these provisions for intra-Islamic strife provide for deviation from the necessity of having a proper authority, the notions of just cause, just intent and limitations on the use of force remain intact.  Hashmi, finds that the operative passage for determining the legitimacy of intra-Islamic strife can be found in the Quranic passage (49:9), which he translates as follows:

If two parties of the believers fall into quarrel, make peace between them; but if one of them transgresses beyond bounds against the other, then fight all of you together against the one that transgresses until it complies with the command of God. But if it complies, then make peace between them with justice, and be fair: For God loves those who are fair (49:9).[xxii]

This passage is the basis for several conclusions on legal use of force in intra-Islamic conflict. Firstly, scholars posit priority for reconciliation, or a peaceful settlement, between fighting factions.[xxiii] Secondly, Hashmi and al-Zuhili indicate that Islamic law does not condemn Muslims on any side of the conflict as a matter of legal theory, but as a matter of factual transgression against Islamic law.[xxiv] Hence, it provides a condensed notion of just cause/right intent and limits on violence altogether. With regard to just cause and right intent, Muslims are not allowed to rise against other Muslims except to correct injustices committed under Islam. Additionally, as Islamic jurisprudence does not provide a neat and obvious separation between ius ad bellum and ius in bello, “transgression” in this passage should probably also be understood to encompass transgressions against norms applicable while in a state of conflict. The terminology “beyond bounds” also seems to suggest that there are different degrees of transgression, meaning that one side can be more in deviation of norms than the other, thus being the more legitimate target of violence. Furthermore, in seeking to restore peace and stability to territories under Islamic jurisdiction, neutral intervention is not the necessary design, but rather intervention against the fighting faction constituting the greatest transgressor under Islamic law. This is especially salient if it is a regime (or possibly armed group such as IS) perpetuating non-compliance. However Hashmi goes on to specify that Islamic legal arguments for intervention against an illegitimate fighting factions stops short of allowing collaboration, involvement or aid from non-Muslim powers (such as US drone support in Iraq).[xxv]

5. Conclusions

The Islamic State probably engages in a discourse of caliphal authority to legitimize their actions by monopolizing just authority; claiming adherence to Islamic goals (just cause) and; claiming the illegitimacy of the structure they fight (identifying the transgressor). It is doubtful however, whether on the basis of Islamic jurisprudence any of their claims could be viewed as legitimate. It is equally doubtful that proclamations of caliphal authority carries the jurisprudential legitimacy that IS may be presumed to be striving for.

Islam, like most major religions, did not develop within the nation-state structure. In fact, it is not intended to be geographically limited but strived to be universal, applicable to all of God’s creation (i.e. the entire world population). While the Caliph has had the historical privilege of raising the banner for the protection (and proliferation) of Islam the proliferation, governed by Jihad is limited. Jihad is a defensive mechanism, at least within its modern interpretations. It is uncertain that even a Caliph would have the right to proclaim violent Jihad on non-Muslim populations in a context where Islam is proliferating quite successfully without the use of force (as has been the case for the last century).

It may be tempting to view caliphal authority as a carte blanche in Islamic ius ad bellum, but it seems that the restrictions concerning just intent and the use of force is applicable at all times, including in intra-Islamic strife. While early Islamic jurisprudence was probably meant to ban intra-Islamic violence outright, the jurisprudence that did develop is generally critical of armed insurrection against authority. In the pan-Islamist interpretation, the state may be viewed as a permanent transgressor as it prevents the realization of the umma whahida, also making it a permanent legitimate target of violence. However, while Islam seems to have little to say in the defense against the state structure concretely, an insurrection against and a state with largely Muslim population would need to consider three things. Firstly, even if a state is automatically a permanent transgressor, there are tenants akin to pacta sunt servanda determining that people’s acquiescence to any form of communal organization is a status quo that should be respected until otherwise agreed upon. Secondly, the regulations on intra-Islamic strife favor reconciliation, i.e. peaceful settlement of disputes. Finally the operative passage suggests that it is the side of the conflict that transgresses “without bounds” that must be opposed. This passage implies that conduct inside and outside of the conflict is crucial and that it is probably not the state which should be the automatic target of violence but rather the side which transgresses the most.



[i] Such as UN Charter (Arts 2(4) and 51), the 1970 Declaration on Friendly Relations, the 1974 UN General Assembly Definition of Aggression or the criteria commonly used to determine the existence of non-international armed conflict.

[ii] D. Baker, ‘Islamic Theory of Statehood’ [1981] Indian Institute of World Culture, 2; S. Hashimi, ‘Is There an Islamic Ethic of Humanitarian Intervention?’ [1992-1993] Ethics and International Affairs, 55.

[iii] Hashimi, (n. ii); M. Khadduri, The Islamic Law of Nations: Shaybani’s Siyar (1st, The John Hopkins Press, Baltimore 2001) 10; H Ko Nakata, ‘Humanitarian Intervention from Sunnite Islamic Perspective’ [2011] The Doshisha International Conference Asian Perspective on Humanitarian Intervention in 21stCentury 1, 1-4.

[iv] W. Al-Zuhili, ‘Islam and International Law’ [2005] International Review of the Red Cross 269, 276-277

[v] S. Hashimi (n. ii) 59; M. Khadduri, The Islamic Law of Nations: Shaybani’s Siyar (1st, The John Hopkins Press, Baltimore 2001), 6;W. Al-Zuhili, ‘Islam and International Law’ [2005] International Review of the Red Cross 269, 270; H Ko Nakata, ‘Humanitarian Intervention from Sunnite Islamic Perspective’ [2011] The Doshisha International Conference Asian Perspective on Humanitarian Intervention in 21stCentury 1, 1-4

[vi] Legal traditions vary application across Islamic collectivities.

[vii] Khadduri (n. v) 7-10.

[viii] S. Hashimi (n. ii) 6-7.

[ix] Al-Zuhili (n. iv) 275.

[x] H. Aboul-Einein and S. Zuhur, ‘Islamic Rulings on Warfare’ [2004] (Strategic Studies Institute, Carlisle); J. T. Johnsson, Holy War Idea in Western and Islamic Traditions (3rd, Pennsylvania University Press, University Park 2002) 93.

[xi] J. T. Johnsson, (n. x) 93; A. R. Murphy, The Blackwell Companion to Religion and Violence (1st, Blackwell Publishing Ltd, Malden 2011).

[xii] R. Kennedy and G. C. Marshall, ‘Is one person’s terrorist another’s freedom fighter? Western and Islamic approaches to ‘just war’ compared’ [1999] Terrorism and Political Violence 1, 9-10; H. Aboul-Einein and S. Zuhur (n. x) 5-6; H Ko Nakata (n. iii) 1, 7.

[xiii] J. T.Johnsson (n. x).

[xiv] R. Kennedy & C. G. Marshall (n. xii) 10.

[xv] Al-Zuhili (n. iv) 279. Translation provided by Al-Zuhili.

[xvi] Al-Zuhili (n. iv) 280.

[xvii] H. Aboul-Einein and S. Zuhur (n. x) 8; See also K. Abou El- Fadl, (1999), The Islamic Law of Rebellion: The Rise and Development on Juristic Discourses on Insurrection, Insurgency and Brigandage (Ph. D. Thesis Princeton University).

[xviii] S. Hashimi (n. ii) 65; H. Aboul-Einein and S. Zuhur (n. x) 9.

[xix] R. Kennedy and G. C. Marshall (n. xii) 11.

[xx] H Ko Nakata (n. xix) 11.

[xxi] D. Baker (n. xv) 5; S. Hashimi (n. ii) 65.

[xxii] S. Hashimi (n. ii) 65.

[xxiii] Ibid; H. Aboul-Einein and S. Zuhur (n. x) 8-9.

[xxiv] S. Hashimi (n. ii) 66; W. Al-Zuhili (n. iv) 274.

[xxv] S. Hashimi (n. ii) 67.

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