Juan Zarate and Sarah Watson [*]
[Full text of this Article in PDF is available at this link]
It is widely assumed that there is no accepted international definition of terrorism, in part because global views on what constitutes terrorism are so politically polarized as to prevent arriving at any meaningful common ground. This view is widespread both in popular culture and the academic community despite the decades of work on this issue at the United Nations (UN), the existence of several UN conventions addressing terrorism, and the increasing convergence of domestic laws on terrorism. In common discourse, any discussion about the definition of terrorism is often met with the relativist quip that “one man’s terrorist is another man’s freedom fighter.”
This Article argues that there is in fact a definition of terrorism that has been widely adopted within the community of nation states, and that this definition is meaningful, substantive, and offers a resolution to some of the most salient debates on the nature of terrorism. Not only are 189 nations party to the UN International Convention for the Suppression of the Financing of Terrorism (“Terrorist Financing Convention”), which offers a basic definition of terrorism, but more than 200 jurisdictions have also committed, through the Financial Action Task Force (FATF), to domestic adoption of a definition of the offense of “terrorist financing” that includes a clear definition of terrorism. Furthermore, a majority of these jurisdictions have actually transposed the FATF definition into their national laws. These include nations, such as the members of the Organisation of Islamic Cooperation, that formerly have led opposition to an international legal definition of terrorism very similar to the definition used by the FATF. While the FATF definition does not resolve all questions, such widespread and consistent adoption implies that the fundamental debates about the definition of terrorism have in fact been quietly concluded.
The literature on the impossibility of defining terrorism has acquired its own collection of literary clichés. It is traditional to begin articles and books about the definition of terrorism with a quote from a thinker of a previous generation reflecting on the difficulties of defining terrorism or a review of definitional efforts stretching back to at least the 1930s.
This Article pays due homage to that tradition with a quote from a man who, in contrast to many thinkers and writers on the issue, was confident that he understood what terrorism involved. Nelson Mandela, speaking in his own defense at his 1964 trial for sabotage and treason, offered a clear taxonomy of violent action: “There is sabotage, there is guerrilla warfare, there is terrorism, and there is open revolution.” He described sabotage as “not involv[ing] loss of life” and as principally involving attacks on economic and infrastructure targets. Although Mandela did not define terrorism, the use of the term in context suggests that he believed terrorism to entail violence directed against human lives rather than (like sabotage) inanimate targets. But at no point did he suggest that South Africans fighting for the overthrow of the apartheid government could not carry out terrorism simply because they were engaged in a struggle against a racist regime.
Nearly sixty years after Mandela’s speech, terrorism remains an intensely contested term. Despite the substantial progress achieved at the UN and FATF, there is no substantive, universally recognized definition that spans academic disciplines or political communities. In the minds of many commentators, the primary obstacle to consensus on the definition of terrorism is the “Nelson Mandela problem”: the perceived need to distinguish “terrorists” from “freedom fighters” (two terms that are frequently held to be mutually exclusive). These commentators reject any definition of terrorism that does not make exceptions for legitimate causes or goals, such as protest, dissent, and even violence against illegitimate regimes. They refuse to label activities by groups whose goals they consider laudable as terrorism, regardless of the nature or consequences of those activities. An equally intense debate rages over whether certain actions by states can or should fall under the rubric of terrorism.
The length and thorniness of the debate reflect the intensely negative valence of the words “terrorism” and “terrorist.” It is very rare for any group involved in conflict to embrace the label of terrorist, and both sides in a conflict may seek to apply the label to their opponents in order to attack the other side’s legitimacy and cut off its access to international support. Beyond these rhetorical and emotional considerations, the question of what constitutes terrorism goes to the center of many of today’s most vexing international security issues and is often at the core of determining legitimacy in international affairs.
The public debate that plays out in media and oratory is so highly charged and politicized that it generally ignores both existing international conventions dealing with terrorism (and related offenses) and the ongoing work at the UN to finalize a counterterrorism convention. Debates about terrorism staged in a legal vacuum create a vicious (or depending on a participant’s goals, virtuous) cycle: the assumption that there is no definition of terrorism in international law lends credence to the idea that the concept is uniquely resistant to definition. It appears that some parties to this debate resist defining terrorism, or reject those definitions that are proposed, because they assume that anything excluded from the definition would be permissible and even acceptable. This only contributes to terrorism’s status as a thing apart, the third rail of international politics. Yet this ignores the fact that many governments have for years successfully prosecuted terrorist offenses in domestic criminal courts and that in the post 9/11 period, the isolation of terrorist groups and prevention of terrorist activities became central features of international security efforts.
This is in contrast, importantly, to genocide, which is an equally highly-charged term but still has a settled definition in international law. This does not mean that all parties to a debate will necessarily agree that a specific action or campaign is genocide, but it is nevertheless possible to have serious discussions about whether specific atrocities do in fact meet the definition of genocide with reference to a specific standard and without suggesting that actions that do not meet the definition are perforce legal or ethical.
This Article argues that there is in fact an internationally accepted definition of terrorism that, while not necessarily qualifying as international law, nevertheless has achieved nearly universal adoption. We argue that the most important moves towards developing an accepted international definition of terrorism, however, have not taken place in the context of the UN, but instead through the auspices of the FATF and its requirements related to the criminalization of the financing of terrorism. The FATF standards are not international law, but more than 200 states or jurisdictions have committed to complying with them, and at least 100 of those jurisdictions (85 percent of those whose definitions have been reviewed to date) have adopted a domestic definition of terrorism that meets this standard.
The FATF process does not create international law, but it shows that it is possible to create a basic legal definition of terrorism that is widely acceptable. Likewise, the FATF definition is not perfect, nor does it put an end to all debates in this area, but it does resolve some fundamental points of difference and clear the stage for a more nuanced debate. In particular, the FATF definition approaches terrorism from the perspective of actions rather than actors; it makes clear that specific actions are terrorism no matter who carries them out or what ends they are seeking to achieve. Under the FATF definition, as Mandela recognized, a freedom fighter can also be a terrorist if the freedom fighter engages in terrorist acts. And the FATF leaves open the possibility that state actors can engage in acts that fall under the definition of terrorism, though such acts would otherwise be considered illegitimate and war crimes under international law.
It is certainly true that the FATF definition, and that definition’s action-based approach, could be used by repressive regimes to suppress dissent. It is also the case that the FATF’s definition does not encompass every evil in the world, and may in fact exclude the murderous actions of nation-states. But any definition, no matter how carefully drawn, can be subject to abuse by various actors, and any definition will have to be applied to specific facts and circumstances.
Scholars and policymakers have been debating the definition of terrorism for nearly a century. It is time to accept that some of these debates have closed—if not in moral or philosophical terms, at least in the arena of international relations. The next step is for policymakers to highlight and formalize this consensus, to use it as a basis for addressing those debates left unresolved, and to build on it to implement a global campaign, similar to historical campaigns against piracy or the slave trade, to eradicate the use of terrorism as a tactic by all actors and in conflicts of any kind.
Part I of this Article contextualizes the problem by providing a background on the current state of debate over the definition of terrorism. Part I.A provides a brief discussion of the need for an international definition of terrorism that enjoys wide, although not necessarily universal, acceptance. Part I.B sketches a high-level outline of the voluminous literature dealing with the definition of terrorism. Part I.C discusses the UN’s work to define terrorism, both through a comprehensive counterterrorism treaty and multiple more focused conventions.
Part II shifts the focus from the UN to the FATF. Part II.A provides explanatory background on the organization and purpose of the FATF and on the nature of its forty recommendations. Part II.B explores the FATF’s definition of terrorism and contrasts it with definitions found in UN conventions. In Part II.C, we examine how the FATF goes beyond purely definitional efforts to ensure that member states are actually operationalizing its definition of terrorism. In light of the FATF’s measures to penalize states that fail to adopt its definition of terrorism, we argue that the FATF and its members have developed and promulgated a definition of terrorism that has become the new international standard.
Part III concludes the Article and provides a summary of outstanding questions.
[*] Juan Zarate is Co-Founder and Chair of the Board, Consilient and Co-Founder and Chair of the Center on Economic & Financial Power at the Foundation for Defense of Democracies (FDD). He previously served as Deputy Assistant to the President and Deputy Natio nal Security Adviser for combating terrorism and as Assistant Secretary of the Treasury for Terrorist Financing and Financial crimes, and was a Visiting Lecturer on Law at Harvard Law School for eight years. Sarah Watson is a Bank Examiner with the Office of the Comptroller of the Currency. The views expressed in this Article are those of the authors alone and do not represent the views of Consilient, FDD, the Office of the Comptroller of the Currency, or the Department of the Treasury.
 See International Convention for the Suppression of the Financing of Terrorism, art. 2(1), Dec. 9, 1999, 2178 U.N.T.S. 197 [hereinafter Terrorist Financing Convention]; FIN.ACTION TASK FORCE, INTERNATIONAL STANDARDS ON COMBATING MONEY LAUNDERING AND THE FINANCING OF TERRORISM & PROLIFERATION: THE FATF RECOMMENDATIONS 13, 41–42, 130 (Oct. 2021), https://www.fatfgafi.org/media/fatf/documents/recommendations/pdfs/FATF%20Recommendations%2020 12.pdf [https://perma.cc/FE64-S649] [hereinafter FATF RECOMMENDATIONS] (identifying and clarifying Recommendation 5 (“Terrorist financing offence”) and defining “terrorist act”).
 See, e.g., John F. Murphy, International Law in Crisis: Challenges Posed by the New Terrorism and the Changing Nature of War, 44 CASE W. RES. J. INT’L L. 59, 61 (2011) (quoting R.R. Baxter); Leonard Weinberg, Ami Pedahzur & Sivan Hirsch-Hoefler, The Challenges of Conceptualizing Terrorism, 16 TERRORISM &POL.VIOLENCE 777, 777 (2004) (quoting Walter Laqueur).
 See, e.g., Ben Saul, Attempts to Define “Terrorism” in International Law, 52 NETH. INT’L L. REV. 57, 57–61 (2005); BRUCE HOFFMAN, INSIDE TERRORISM 1–21 (3d ed. 2017); Geoffrey Levitt, Is “Terrorism” Worth Defining?, 13 OHIO N.U. L.REV. 97, 97–108 (1986); William R. Farrell, Terrorism Is…?, 33 NAVAL WAR COLL.REV. 64, 64–66 (1980).
 Nelson Mandela, I Am Prepared to Die, Statement from the Dock at the Opening of the Defence Case in the Rivonia Trial (Apr. 20, 1964), https://www.un.org/en/events/mandeladay/court_statement_1964.shtml [https://perma.cc/2NGW-5VQM].
 See id.
 See id.
 See, e.g., THE ROUTLEDGE HANDBOOK OF TERRORISM RESEARCH (Alex P. Schmid ed., 2011) (presenting over 250 definitions of terrorism).
 For an argument that there is a clear distinction between terrorists and freedom fighters, see President Ronald Reagan, Radio Address to the Nation on Terrorism (May 31, 1986), https://www.reaganlibrary.gov/archives/speech/radio-address-nation-terrorism [https://perma.cc/4S53-ZWSL] (“Freedom fighters do not need to terrorize a population into submission. Freedom fighters target the military forces and the organized instruments of repression keeping dictatorial regimes in power. Freedom fighters struggle to liberate their citizens from oppression and to establish a form of government that reflects the will of the people. . . . Terrorists intentionally kill or maim unarmed civilians, often women and children, often third parties who are not in any way part of a dictatorial regime. Terrorists are always the enemies of democracy.”).
 See Boaz Ganor, Defining Terrorism: Is One Man’s Terrorist Another Man’s Freedom Fighter, 3 POLICE PRAC. & RSCH. 287, 291–92 (2002) (noting the insistence on the part of Fatah and Black September leader Salah Khalef that he was “firmly opposed to . . . terrorism” but that “revolutionary violence” should not be “confuse[d]” with “terrorism”).
 See Igor Primoratz, Terrorism is Almost Always Morally Unjustified, But It May Be Justified as the Only Way of Preventing a “Moral Disaster,” LSE EUR. POL. & POL’Y (Apr. 29, 2013), https://blogs.lse.ac.uk/europpblog/2013/04/29/terrorism-moral-disaster-justifiedigor-primoratz-philosophy [https://perma.cc/RPR3-H5GF] (describing the definitional debate as “clouded by emotions, moral passions, and political interests”).
 For a pithy expression of the assumption that what is not defined as “terrorism” is necessarily permitted, see Igor Primoratz, State Terrorism and Counterterrorism, in ETHICS OF TERRORISM AND COUNTER-TERRORISM 69, 69 (Georg Meggle et al. eds., 2004) (quoting Roger Woddis, Ethics for Everyman, in THE NEW OXFORD BOOK OF LIGHT VERSE 292 (Kingsley Amis ed., 1978)(“Throwing a bomb is bad, / Dropping a bomb is good; / Terror, no need to add, / Depends on who’s wearing the hood.”).
 Convention on the Prevention and Punishment of the Crime of Genocide, art. II, Dec. 9, 1948, 78 U.N.T.S. 277, 280.
 On whether the killings in Darfur amounted to genocide, see, for example, Jamie A. Mathew, The Darfur Debate: Whether the ICC Should Determine That the Atrocities in Darfur Constitute Genocide, 18 FLA.J.INT’L L. 517 (2006); Jennifer Trahan, Why the Killing in Darfur is Genocide, 31 FORDHAM INT’L L.J. 990 (2008).
 Consolidated table of assessment ratings, FIN. ACTION TASK FORCE (Feb. 10, 2022) [hereinafter FATF, Fourth Round Ratings] (column R.5) http://www.fatfgafi.org/media/fatf/documents/4th-Round-Ratings.pdf [https://perma.cc/6PG6-LG8B].