International Humanitarian Law and Terrorism

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War and terrorism both refer to the notion of collective violence. War is, however, an older and better defined term in which both sides may acknowledge that they are at war.1Marco Sassoli, ‘Terrorism and War’ (2006) 4 J Int’l Crim Just 959 Few, on the other hand, describe their methods as terrorism, a term which is very much charged with emotion.2Danja Blocher, ‘Terrorism as an International Crime: The Definitional Problem’ (2011) 8 Eyes on the ICC 107 Sassoli states that “[t]errorism is a term describing what others do”3Sassoli, ‘Terrorism and War’ (supra n.1) and is often used to delegitimise and discredit the opposing side. The issue of how to define terrorism has vexed the international community for decades and no consensus has yet been reached.4Michael P. Scharf, ‘Defining Terrorism as the Peacetime Equivalent of War Crimes: Problems and Prospects’ (2004) 36 Case W Res J Int’l L 359 Moreover, the counter-terrorism regime, particularly as it has developed post-9/11, has become ever more conflated with IHL. The potential regime conflict between these two areas of law occur when they regulate the same conduct, imposing sometimes contradictory obligations which results in a blurring of the distinction between the two. This is a subject of much debate with little agreement as to where and when these regimes can operate in tandem and how they can interact without conflict.

This month at the Diplomacy, Law and Policy Forum, we seek to enhance understanding of these regimes of law. The articles on the platform discuss the need for harmony between the two regimes which may be achieved through exclusion clauses, the ways in which humanitarian crises can increase terrorism recruitment, and the phenomena of foreign terrorist fighters. Not only are all of these contentious issues within international law today, they are also topics requiring academic discussion, particularly in the global South which is often the target of the counter-terrorism regime.

Definition of Terrorism

A key issue in analysing the interaction between the terrorism suppression and IHL regimes is the fact that there is no single, universally accepted definition of terrorism. This disagreement is largely between developed states and developing states as to the characterisation of individuals as terrorists or freedom fighters.5Sebastien Jodoin, ‘Terrorism as a War Crime’ (2007) 7 Int’l Crim L Rev 77 Immediately after the 9/11 attacks, the General Assembly created a working group to develop a comprehensive convention on international terrorism.6Scharf, ‘Defining Terrorism as the Peacetime Equivalent of War Crimes: Problems and Prospects’ (supra n.4) However, it has been left in its drafting stage as many developing states wanted to exclude struggles for liberation and self-determination from their purview.7Sassoli, ‘Terrorism and War’ (supra n.1) The working group nearly reached a consensus on the following definition:

Terrorism is an act intended to cause death or serious bodily injury to any person; or serious damage to a State or government facility, a public transportation system, communication system or infrastructure facility… when the purpose of such an act, by its nature or context, is to intimidate a population, or to compel a Government or an international organization to do or abstain from doing an act.8As quoted in Scharf, ‘Defining Terrorism as the Peacetime Equivalent of War Crimes: Problems and Prospects’ (supra n.4)

However, Malaysia, on behalf of the Organization of the Islamic Conference (OIC), wanted the following caveat added:

Peoples’ struggle including armed struggle against foreign occupation, aggression, colonialism, and hegemony, aimed at liberation and selfdetermination in accordance with the principles of international law shall not be considered a terrorist crime.9As quoted in Scharf, ‘Defining Terrorism as the Peacetime Equivalent of War Crimes: Problems and Prospects’ (supra n.4)

The Arab, OIC and Organization of African Unity (OAU) Conventions on terrorism exclude national liberation wars and resistance against foreign occupation from their scope of application.10Sassoli, ‘Terrorism and War’ (supra n.1) Their argument for doing so rests on the implicit point that terrorism may be justified if committed for the right reasons, in effect stating that the ends justifies the means, bringing to light the cliche that “what is terrorism to some is heroism to others”.11Jodoin, ‘Terrorism as a War Crime’ (supra n.5) Pakistan has also precluded the application of the International Convention for the Suppression of Terrorist Bombings to fights of people for their right to self-determination.12UN Treaty Collections, International Convention for the Suppression of Terrorist Bombings, Pakistan

Meanwhile Western states have used the rhetoric of terrorism to delegitimise certain actions as wrongful at the same time characterising any counterterrorism efforts as a war of good against evil.13Jodoin, ‘Terrorism as a War Crime’ (supra n.5) In so discrediting certain individuals or groups, the label of terrorist aims to dehumanise them and portray them as irrational actors who cannot be reasoned with.14ibid. It has been said that this ends up shutting down any worthwhile debate on policy or tactics.15ibid. An added difficulty is the fact that operations with the intention of stopping terrorist activities have been known to violate basic legal restraints themselves, subjecting prisoners to mistreatment or torture.16Adam Roberts, “Counter-terrorism, armed force and the laws of war”, Survival, Vol. 44, Spring 2002, p. 13 This also very counterproductively can contribute to the growth of a terrorist campaign against the government committing such excesses.17ibid.

Despite the fact that historically the international community was unable to define terrorism, the Security Council, following the attacks of 9/11, passed Resolution 1373 which obliges states to fight terrorism and prohibits giving financial support to persons and organisations engaged in terrorism.18Security Council Resolution 1373 (2001) S/RES/1373 (2001) However, given the difficulties in definition, it left it to Member States to adopt a definition of terrorism within their national laws. Terrorism was also discussed for inclusion as a war crime at the negotiations for the Rome Statute, however, it was not incorporated due to the lack of agreement as to what the term means.19Nabil Mokaya Orina, ‘A Critique of the International Legal Regime Applicable to Terrorism’ (2016) 2 Strathmore LJ 21 Since then, the Special Tribunal for Lebanon in 2011 also offered its own definition of terrorism in a case where they held that terrorism had become a crime under customary international law.20Prosecutor v. Ayyash, Case No. STL-l l-01/l/AC/RI76bis, Interlocutory Decision on the Applicable Law: Terrorism, Conspiracy, Homicide, Perpetration, Cumulative Charging, T II. B. (Special Trib. for Lebanon Feb. 16, 2011) However, the decision has been disputed on numerous grounds, significantly for the fact that a definition of terrorism upon which there is consensus does not exist in international law.21Aleksandar Marsavelski, ‘The Crime of Terrorism and the Right of Revolution in International Law’ (2013) 28 Conn J Int’l L 243 There is still no accepted definition today and this issue continues to impact the entire counter-terrorism regime.

Interaction between the Terrorism Suppression Regime and IHL

There are currently 12 universal instruments which seek to prevent and punish terrorism, also known as the terrorism suppression regime or the counter-terrorism regime (CT). These cover specific categories of terrorist acts including offences against civil aviation such as aircraft hijacking, attacks against internationally protected persons, bombings, the financing of acts of terrorism, and the protection of nuclear materials.22Full list: 1963 Convention on Offences and Certain Other Acts Committed On Board Aircraft, 1970 Convention for the Suppression of Unlawful Seizure of Aircraft, 1971 Convention for the Suppression of Unlawful Acts against the Safety of Civil Aviation, 1973 Convention on the Prevention and Punishment of Crimes against Internationally Protected Persons, including Diplomatic Agents, 1979 International Convention against the Taking of Hostages, 1980 Convention on the Physical Protection of Nuclear Material, 1988 Protocol for the Suppression of Unlawful Acts of Violence at Airports Serving International Civil Aviation, supplementary to the Convention for the Suppression of Unlawful Acts against the Safety of Civil Aviation, 1988 Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation,1988 Protocol for the Suppression of Unlawful Acts against the Safety of Fixed Platforms Located on the Continental Shelf, 1991 Convention on the Marking of Plastic Explosives for the Purpose of Detection, 1997 International Convention for the Suppression of Terrorist Bombings, 1999 International Convention for the Suppression of the Financing of Terrorism Due to the lack of a comprehensive definition, these conventions take a thematic and piecemeal approach to criminalise certain terrorist offences.23Jodoin, ‘Terrorism as a War Crime’ (supra n.5)

The issue with conflating issues of terrorism with those in an armed conflict is the fact that they both regulate different things, namely the CT regime focuses on protecting the State from a national security perspective, whereas IHL centres on protecting those not participating in hostilities from unnecessary and disproportionate attack.24Cuyckens, H., & Paulussen, C. (2019). The Prosecution of Foreign Fighters in Western Europe: The Difficult Relationship Between Counter-Terrorism and International Humanitarian Law. Journal of Conflict and Security Law.

A way to circumvent this issue of conflation and the blurring of distinctions between what is terrorism and what is armed conflict is the persuasive notion that the CT regime operates in peacetime whereas the lex specialis, IHL, would apply during an armed conflict. This finds support in the various exclusion clauses found in CT treaties which exclude the activities of armed forces during an armed conflict from their scope of application. These clauses exist in the 1979 Hostages Convention, the 1997 Terrorist Bombings Convention, the 1999 Terrorist Financing Convention and the 2005 Nuclear Terrorism Convention.25Article 12 of the 1979 Hostages Convention, Article 19(2) of the 1997 Terrorist Bombings Convention, Article 2(1)(b) of the 1999 Terrorist Financing Convention, Article 4(2) of the 2005 Nuclear Terrorism Convention These conventions also exclude the “activities of armed forces during an armed conflict, as those terms are understood under IHL, which are governed by that law”, though it is unclear whether the term armed forces includes members of non-state armed groups.26Sandra Krahenmann, ‘The Interplay between International Humanitarian Law, Terrorism and the Foreign Terrorist Fighter Regime’ (2018) 112 Am Soc’y Int’l L Proc 307

Historically, the notion of terrorism was held to have ‘no legal acceptation’ according to an ICRC publication for a 1971 Conference, with an American Representative at one of the Geneva Diplomatic conferences of 1974-77 stating that “[t]errorism was an excessively vague word of which no satisfactory definition existed”.27Jodoin, ‘Terrorism as a War Crime’ (supra n.5) This is also because already IHL prohibits a certain number of acts which would be qualified as terrorist leading some to argue that the use of terror in war was already prohibited by the laws of war.28ibid. For instance, it prohibits the execution of civilians and those hors de combat, the taking of hostages, and the deliberate targeting of civilians and civilian objects.29Attacks on civilians and civilian objects are prohibited under Article 51(2) and 52, Additional Protocol I and Article 13, Additional Protocol II; indiscriminate attacks are prohibited under Article 51(4), Additional Protocol I; the taking of hostages is prohibited under Article 75, Additional Protocol I, Common Article 3(1)(b), and Article 4(2)(b), Additional Protocol II; the murder of persons not or no longer taking part in hostilities is prohibited under Article 75, Additional Protocol I, Common Article 3(1)(a), and Article 4 (2)(a), Additional Protocol II Under Article 33 of the Fourth Geneva Convention collective punishment and all members of intimidation of terrorism are punished, and Additional Protocol II extends this to non-international armed conflicts. Moreover, IHL also specifically prohibits ‘acts or threats of violence the primary purpose of which is to spread terror among the civilian population’.30Article 51(2) of Additional Protocol I and Article 13(2) of Additional Protocol II This was upheld by the International Criminal Tribunal for the Former Yugoslavia in the Galić case.31ICTY, Prosecutor v. Stanislav Galić, Case No. IT-98-29-T, Judgment and Opinion, 5 December 2003, § 769.

The key difference in an armed conflict then is that IHL condones certain attacks as lawful or unlawful whereas any act of violence which is terrorist is always unlawful.32Cuyckens & Paulussen, ‘The Prosecution of Foreign Fighters in Western Europe’ (supra n.24) IHL prohibits acts of terrorism only when committed against certain protected persons. This is a problem when, for instance, some definitions of terrorism include acts directed at soldiers or government property. Under IHL, attacking enemy combatants or property which are military objectives are not prohibited so long as the attacks are proportionate.33Sassoli, ‘Terrorism and War’ (supra n.1) It also defines terrorist acts in an apolitical manner as those committed by States or non-state actors against non-combatants with the specific intent to terrorise them.34Jodoin, ‘Terrorism as a War Crime’ (supra n.5) The intention to spread terror among civilians is a necessary element as any attack may create fear even if it directed against a lawful target.35Hans-Peter Gasser, ‘Acts of terror, terrorism and international humanitarian law’ (2002) 84 Int’l Rev Red Cross 547

The ways in which these regimes interact is problematic then when the CT regime, if applied in an armed conflict, renders unlawful otherwise legal attacks under IHL (i.e. proportionate attacks on the military objectives of a State). This conflict may be resolved by concluding that the CT regime applies in peacetime, as supported by the exclusion clauses in terrorism suppression conventions, whereas IHL, as the lex specialis, applies in times of war. The phenomena of foreign terrorist fighters also offers another form of resolution – in that the CT regime may criminalise conduct occurring outside the conduct of hostilities whereas IHL applies to all acts undertaken during an armed conflict. It is to this avenue for resolution that we now turn.

Foreign Terrorist Fighters

Foreign terrorist fighters have been defined in Security Council Resolution 2178 as those individuals who travel to a State other than their State of residence or nationality in order to perpetrate, plan, prepare, or participate in terrorist acts or provide or receive terrorist training.36Security Council Resolution 2178 (2014) S/RES/2178 (2014) The issue with this definition and the concept of FTFs is that while their regulation occurs mainly under the counter-terrorism regime, their conduct has to also be assessed according to the law of armed conflict. Much of the concern under the counter-terrorism regime is centred on what they may do upon return to their State of origin and how to handle them as a national security risk. Meanwhile IHL focuses on conduct during war and ensuring that this is lawful and that those not participating in hostilities are duly protected.

Under IHL, those who directly participate in hostilities on the behalf of a non-state group in a non-international armed conflict, which is what most foreign terrorist fighters do, are considered to be fighters or ‘unprivileged combatants’.37Cuyckens & Paulussen, ‘The Prosecution of Foreign Fighters in Western Europe’ (supra n.24) This means that they may be prosecuted for the taking up of arms and for IHL violations. This in and of itself is a controversial topic as it arguably reduces the likelihood of compliance with IHL if those participating will be tried for lawful acts of war.38ibid. The issue remains as to what regime of law foreign terrorist fighters would be prosecuted under and the conduct they will be held responsible for. Judges trying returning foreign terrorist fighters face the question of how to apply both regimes of law and whether to hold them liable for otherwise lawful acts of war under the CT regime.

Courts have, however, demonstrated a certain amount of flexibility and have handled such cases surprisingly well. Indeed, German courts have held that both regimes apply and have managed to resolve any norm conflict between them. They have prosecuted returning FTFs for their membership of a terrorist group as well as war crimes – applying both the IHL and CT regimes to their conduct.39ibid. For instance, a German national who joined IS faced war crimes for letting a Yazidi child she had enslaved die of thirst. She has also been charged for being a member of a terrorist organisation.40ibid. Cuyckens and Paulussen argue in favour of this approach stating that they should be prosecuted for membership and training and all acts which fall outside the conduct of hostilities under CT law as well as for acts committed in the conduct of hostilities under IHL. They state that “[t]he important thing is for the acts committed during the conduct of hostilities, ie when the FFs are actually engaged in fighting in the ongoing NIAC, to be assessed under IHL rather than CT legislation in order to prevent FFs from being prosecuted for acts that might be prohibited under CT but not under IHL”.41ibid. This approach privileges the lex specialis, IHL, for acts during active hostilities, and takes into account the CT regime for all ancillary acts and in my opinion is an adequate compromise to this norm conflict.

Humanitarian Assistance

The CT and IHL regimes also differ when it comes to the provision of humanitarian assistance in a non-international armed conflict. IHL recognises the importance of engaging with non-state armed groups in a NIAC in order to allow for humanitarian assistance.42Naz K. Modirzadeh, Dustin A. Lewis & Claude Bruderlein, ‘Humanitarian engagement under counter-terrorism: a conflict of norms and the emerging policy landscape’ (2011) 93 Int’l Rev Red Cross 623 However, the CT regime prohibits the provision of material support to ‘terrorist’ groups.43ibid. IHL seeks to balance security interests with humanitarian concerns by ensuring that life-saving goods and services reach civilians and those hors de combat during hostilities. In doing so, humanitarian organisations may need to negotiate access with non-state groups which may consequently derive indirect or direct benefits from this assistance. Under the CT regime, however, the prohibition on providing material support to ‘terrorist’ groups may result in a ‘chilling effect’.44ibid. This occurs when organisations are faced with sanction or are intimidated by strict and confusing protocols required in areas where ‘terrorist’ groups are active may decide to stop or cut back on projects in these areas.45ibid. This may adversely impact civilians in need in areas where humanitarian organisations do not wish to risk liability and so may prefer to not provide services at all.46ibid. While it is not likely that this norm conflict will be played out before the courts it is necessary that IHL is complied with over the CT regime here as it may result in harm to civilian populations in humanitarian need. In doing so, the CT regime should adopt IHL provisions in allowing for humanitarian access.


Jodoin argues that “[i]f the primary purpose of the law of armed conflict is the limitation of chaos and human suffering prevalent in armed conflicts, then its potential to address the anarchy and anguish caused by terrorism is significant”.47Jodoin, ‘Terrorism as a War Crime’ (supra n.5) As a result, the law of armed conflict may be a useful tool in the so-called war against terrorism as its more universal acceptance renders unlawful many acts which would fall into the category of terrorism. Moreover, while the post-9/11 counterterrorism regime has encroached into the realm of armed conflict and risks blurring the distinction between the two, there are opportunities for resolving this conflation. Namely, the approach taken by the German courts seem appropriate, in reserving IHL for actual hostilities and applying CTL for all actions ancillary to it such as membership and training. At the same time, other issues such as humanitarian assistance remain in need of resolution. It is also important to note that the so-called war on terror has been used by states to allow for excess and the erosion of human rights and civil liberties. Wars should be against proper nouns which are identifiable actors in a conflict rather than against common nouns, such as crime, poverty or terrorism, which risk upending the rule of law in their wake.