September 28, 2001

David Turns
LL.M (London), Barrister, Lecturer in Law, The Liverpool Law School

The attacks on the WTC and the Pentagon were definitely not an act of war in any legal sense, because international law no longer speaks in terms of “wars” but of “armed conflicts,” usually understood to be between States (although internal conflicts of great intensity may also be included). The term "act of war" is now only used rhetorically by States that feel threatened by a particular hostile activity; it has to all intents and purposes lost the legal significance it had pre-1945, when it signified a hostile act terminating the operation of normal peacetime international law between the belligerents and activating the provisions of the jus in bello.

I suspect that when President Bush employed the term "act of war" he did so with no inkling of any possible legal connotations. In my view it was used entirely rhetorically, for domestic political, media, and popular consumption – with the effect (probably intended) of a warning of impending military action by U.S. armed forces.

Individuals or groups cannot be "at war" with States, for the same reason that the September 11 attacks cannot be regarded as an "act of war" in any legally meaningful sense. In the parlance of international law, "armed conflict" requires two or more State belligerents, or a conflict within one State, but with a high threshold of intensity. "Isolated and sporadic acts of terrorism" are expressly excluded, and there is a requirement that the non-State belligerent be in control of territory within the State and be capable of mounting "sustained and concerted military operations".

There seems little doubt that the September 11 attacks will pose a challenge to the future development of the legal definition of "armed conflict" and the specific rules applicable in such conflicts. There is a real risk that 21st Century "asymmetric" conflicts, such as those opposing one or more States and terrorist organizations without a clear territorial link, will increasingly subvert the traditional inter-State or internal rebellion scenarios that have so far been at the heart of the jus in bello.

This does not mean that we are unable to define the attacks at all. The destruction of the WTC can undoubtedly be considered an act of terrorism under Article 2(1) of the 1998 International Convention for the Suppression of Terrorist Bombings:

"Any person commits an offence within the meaning of this Convention if that person unlawfully and intentionally delivers, places, discharges or detonates an explosive or other lethal device in, into or against a place of public use, a State or government facility, a public transportation system or an infrastructure facility: (a) With the intent to cause death or serious bodily injury; or (b) With the intent to cause extensive destruction of such a place, facility or system, where such destruction results in or is likely to result in major economic loss".

The attacks may also be viewed, for international law purposes, as violating the 1970 Hague Convention for the Suppression of the Unlawful Seizure of Aircraft.

For domestic law purposes, they would obviously amount to common crimes (murder, conspiracy), albeit on a dramatic scale. The categories of terrorism and common crimes are not mutually exclusive, although, in the absence of an international tribunal with appropriate jurisdiction, the applicability of charges formulated under the conventions mentioned above would depend on the extent to which those conventions had been incorporated into the domestic law of the State concerned.

One could make the argument that the attack on the WTC was a crime against humanity, because it was clearly targeted at a civilian population. But international case law is as yet divided on how to define the requirements of this crime. The main areas of disagreement concern 1) whether a crime against humanity can occur in peacetime, or whether there must be a state of armed conflict; 2) whether a single atrocious act may qualify, or whether there must be a pattern, or campaign, of actions; and 3) whether there was must be State participation or endorsement of the action in question.

The 1998 Statute of the International Criminal Court does not specify any requirement of an armed conflict. Article 5 of the ICTY Statute requires a nexus to an armed conflict, but this document was intended only for the purposes of the Tribunal and not for international law in general. The case rulings of the ICTY tend to veer away from absolutely requiring a nexus to armed conflict.¹

A more difficult question is whether an isolated act can amount to a crime against humanity. On this point, the ICTY has issued contradictory statements. In The Prosecutor v. Kupreskic et al. (January 14, 2000), it noted that a crime against humanity is normally understood to occur within a "course of conduct." However, in the next sentence and accompanying footnotes, the ruling went on to quote from the Trial Chamber’s decision in The Prosecutor v. Tadic (May 7, 1997): "in certain circumstances, a single act [has qualified] when it occurred within the necessary context." While it might credibly be suggested that the "necessary context" of the attack on the WTC is a campaign of terrorism against the U.S., international case law has traditionally required such context to be in the form of a plan or policy formulated, or at least tolerated, by a State or de facto governmental authority. If this is correct, it would have to be proved that such an entity sponsored, or at least tolerated, the attack on the WTC.

On that issue, the present position is, to put it mildly, confused. In Tadi_, the ICTY stated that while crimes against humanity "are not isolated, random acts of individuals [deliberately targeting a civilian population]" …this no longer needed to be in the form of a State policy. In The Prosecutor v. Nikoli² , it was stated that the acts did not need to be part of a State policy as such, but could not be the work of isolated individuals acting alone. On the other hand, national decisions in Canada (Reg. v. Finta, 1994) and France (Barbie, 1988, and Touvier, 1992) have strongly emphasized the requirement of a State policy. In Kupreskic, the ICTY concluded its discussion of this difficult and controversial issue with the tentative suggestion that, in cases where there the perpetrators of crimes against humanity have no official status and do not act on behalf of any governmental authority, "some sort of explicit or implicit approval or endorsement by State or governmental authorities is required, or else … the offense [must] be clearly encouraged by a general governmental policy or … clearly fit within such a policy."³

This being the current state of international law as pronounced by an authoritative international tribunal, I would conclude that in the last analysis, the attack on the WTC probably cannot be correctly regarded as a crime against humanity. However, given the contradictions and uncertainties manifest in the ICTY’s discussion over a range of cases, I would not exclude the possibility that international law could be developed in future so as to assimilate terrorist acts targeted exclusively against civilian populations to crimes against humanity. Moreover, the ICC Statute’s reference to the definition of crimes against humanity as being part of "a State or organizational policy" might lend support to such a future development, if terrorist organizations are deemed to be sufficiently "organizational".

The attack on the Pentagon, in my view, cannot be considered a crime against humanity because of the military nature of many of the building’s occupants and its function as a command and control center for U.S. armed forces. The mere presence of civilians among a target group also including military personnel is not sufficient to transform such an act into a crime against humanity, as the latter must be directed against a civilian population as such.⁴

In the catalogue of international crimes included in the September 11 attacks, I would not include hostage-taking. This is because the hijackers did not compel a third party to do or abstain from doing any act, as specified in Article 1(1) of the 1979 International Convention against the Taking of Hostages. The acts committed were clearly criminal, but the relevant anti-terrorist convention does not make them into international crimes (i.e. direct violations of international law) as such; it merely requires States Parties to criminalise such conduct in their domestic law and to co-operate with other States in the investigation and prosecution of such conduct.

Of course, any State military response to the attacks of September 11 is constrained at all times by international humanitarian law. At its most basic, this includes, but is not limited to, the requirements to discriminate between military and civilian targets, and to balance proportionality against considerations of military necessity in inflicting civilian casualties and collateral damage. It is forbidden to attack civilians or civilian objects as such and to use weapons which will, or are likely to, cause unnecessary suffering. Although specific treaty instruments enshrining these rules may not always be applicable per se (e.g. the U.S. is not technically bound by the strict letter of the 1977 Protocol I Additional to the 1949 Geneva Conventions because it has never ratified the Protocol), most IHL provisions are now considered to be part of customary international law and therefore legally binding on all States. Non-State actors in an international armed conflict are in much more obscure position, as they cannot be parties to international agreements. International humanitarian law would regard them as unlawful combatants not entitled to the conflict-specific protection laid down in that body of law, but the principles of humanity and reciprocity would suggest that, as a minimum, they should enjoy fundamental guarantees of human rights on capture by State armed forces, who could nevertheless try them for criminal acts committed prior to capture.

A State has the right in international law to defend itself against the perpetrators of an armed attack on its territory, which can include a terrorist attack. Attacks on any States proved to be behind the attacks would also be justifiable on the basis of self-defense. As noted above, any action undertaken in self-defense will have to respect the requirements of necessity and proportionality, and must not be unreasonable or excessive.

If action is taken in self-defense, no prior authorization is required from the UN Security Council, although there is an obligation to report to the Council any actions so taken. However, Article 51 of the UN Charter, which enshrines the customary law right to self-defense, requires that the need for response be instant and overwhelming, with an element of urgency leaving no time for deliberation or reflection. The longer the U.S. waits before responding militarily to the September 11 attacks, the less it may look like pure self-defense, as the concept is understood in international law, and the more it may begin to appear purely retributive, and correspondingly less lawful, in nature.

In any event it may be advisable for the sake of legality – particularly in view of the broad anti-terrorist coalition which the U.S. is trying to create – to seek a mandate from the Security Council for an enforcement action under Chapter VII of the Charter. Although in the past such actions have invariably been directed against States, in view of the grave threat to international peace and security posed by terrorism in the current crisis, there should be no legal problem in obtaining a Security Council mandate for an action designed to restore international peace and security by removing the threat of terrorism. NATO actions obviously need the mandate of the North Atlantic Council.

"Retaliation" and "revenge" are not concepts recognised per se in the international law regulating the resort to armed force by States; reprisals, however, are. They consist in acts which would normally be illegal, but are in response to prior illegal acts by another State and are undertaken with the sole objective of securing a cessation of the prior illegal activity. They must be preceded by an unsatisfied demand for reparation by the injured State and must be strictly proportionate to the original harm inflicted. Since the introduction of the UN Charter, the consensus view of reprisals involving the use of armed force has been that they are only lawful if they amount to actions taken in self-defense, in which case they must comply with the legal requirements of self-defense. Reprisals have never expressly been invoked by States in response to international terrorism.

At present no such courts exist at the international level. The ICTY and ICTR are limited to crimes committed in the former Yugoslavia and Rwanda, respectively, and the ICC is not as yet operational pending the entry into force of its Statute. In any event, none of these institutions have or will have jurisdiction over acts of terrorism.

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