The Special Tribunal for Lebanon (STL), set up in The Hague to try those responsible for the 2005 bombing that killed former Lebanese prime minister Rafiq Hariri and 22 others, is the first international court with jurisdiction over the crime of terrorism.Footnote ¹ On 16 February 2011, the STL Appeals Chamber issued an Interlocutory Decision on the applicable law, having been asked by the pre-trial judge to clarify the law on 15 points.Footnote ² This unanimous Decision is a landmark ruling that has sparked debate amongst legal practitioners and scholars. Two of those, Kai Ambos and Ben Saul, will comment on the ruling in this symposium. As an introduction to their comments, we briefly discuss the most important points of the Appeals Chamber's decision.

The Chamber answered the questions put to it by the pre-trial judge under the following headings: (I) Interpretation of the STL Statute, (II) The notion of terrorism to be applied by the Tribunal, (III) Other crimes falling under the jurisdiction of the STL, (IV) Modes of criminal responsibility, and (V) The question of cumulative charging.

As to the first issue – the interpretation of the STL Statute – the Appeals Chamber held that the Tribunal is to apply Lebanese law as interpreted and applied by Lebanese courtsFootnote ³ unless such interpretation or application is unreasonable, would result in manifest injustice, or is non-consonant with international principles and rules binding Lebanon.Footnote ⁴ Interestingly enough, the Chamber does not rely on international law in that modest manner, namely as a correction mechanism or for the sole purpose of filling a lacuna. Instead, it adopts an activist ‘internationalist approach’ by granting international law a more autonomous role in the interpretation and application of the Lebanese definition of ‘terrorism’.Footnote ⁵

This touches upon the second issue – the notion of terrorism, arguably the most controversial part of the ruling. In light of the narrow interpretation of the Lebanese definition by Lebanese courts,Footnote ⁶ the STL felt a need to resort to the international law.Footnote ⁷ It used this opportunity to articulate some thoughts on the customary international-law status of the crime of terrorism.Footnote ⁸ As the judges conceded, ‘[i]t is held by many scholars and other legal experts that no widely accepted definition of terrorism has evolved in the world society because of the marked difference of views on some issues’.Footnote ⁹ Yet, they continued that ‘[c]loser scrutiny reveals that in fact such a definition has gradually emerged’.Footnote ¹⁰ According to the Appeals Chamber, this definition had customary international-law status at least in relation to the international crime of terrorism committed in times of peace.Footnote ¹¹ On the basis of treaties, UN resolutions, and the legislative and judicial practice of states, the following key elements of such a crime were identified: (i) the perpetration of a criminal act or threatening such an act; (ii) the intent to spread fear among the population or directly or indirectly coerce a national or international authority to take some action, or to refrain from taking it; and (iii) the involvement of a transnational element.Footnote ¹² The Chamber also held that a broader norm on terrorism in times of armed conflict was incipient.Footnote ¹³

Since the key elements of the identified international definition were more broadly phrased than Lebanese law and practice, particularly with regard to the means of carrying out the terrorist act (not limited, as in Lebanese law, to the use of specific means, instrumentalities, or devices), the Chamber's interpretation of the Lebanese Criminal Code resulted in extending liability for terrorism under Lebanese law.Footnote ¹⁴ This was justified, according to the judges, because of the unique gravity and transnational dimension of the crime of terrorism.Footnote ¹⁵ This interpretation did not violate the principle of legality (nullum crimen sine lege), the Chamber added, since it was consistent with the offence as defined under Lebanese law. Moreover, it was accessible to the accused, given the publication of the relevant treaties in the Official Gazette and thus reasonably foreseeable.Footnote ¹⁶ The Chamber then held that the notion of terrorism to be applied by the STL consisted of three elements: (i) the volitional commission of an act, (ii) through means that are liable to create a public danger, and (iii) the intent of the perpetrator to cause a state of terror.Footnote ¹⁷

The third issue that the Chamber addressed concerned the question of which law should be applied to the other crimes falling under the jurisdiction of the STL: intentional homicide, attempted homicide, and conspiracy. Here, the Chamber adopts a purely ‘national approach’ and held that it shall apply Lebanese law, since no equivalents existed for these crimes in international criminal law.Footnote ¹⁸ Conspiracy was merely relevant as an inchoate crime with regard to genocide.

The fourth issue discussed the law applicable to modes of liability. On this point, the Chamber proposed to apply both Lebanese and international law. The Court should determine, on a case-by-case basis, whether there is a difference between modes of liability under Lebanese and international law and, if so, apply the more favourable law to the accused.Footnote ¹⁹ With regard to perpetration and co-perpetration, the Chamber found that there was an overlap and that both international and Lebanese law may be considered in interpreting co-perpetration.Footnote ²⁰ With regard to complicity, Lebanese law should be applied, since it is more circumscribed on both the mental element (it requires proof of knowledge of the base crime, an agreement to commit the crime, and sharing the principal's intent to further the crime) and the material element (the provision lists means by which the accomplice will support the commission of a crime).Footnote ²¹ With regard to participation in a group with a common purpose, the Chamber held that the international law on joint criminal enterprise (JCE liability) could be harmonized with Lebanese law. This also applies to the extended form of JCE liability (JCE III), which exists under Lebanese law as well. However, according to the Chamber, the extended JCE form does not apply to terrorism, since international law stipulates that it does not square with special-intent crimes such as genocide and, indeed, terrorism. Again, the Chamber found that it would evaluate on a case-by-case basis whether there is conflict between Lebanese and international notions of joint-purpose liability. In case there is no conflict, Lebanese law applies. In case there is, the most favourable body of law applies.Footnote ²²

The last issue concerns the question of cumulative or alternative charging. The Chamber decided that only when the charged offences are truly distinct, in that they have specific elements that make them different, can the accused be charged cumulatively. With regard to modes of liability, the Chamber decided that these should always be charged alternatively when they relate to the same offence.Footnote ²³

The STL identification of a general definition of ‘terrorism’ under international law is a breakthrough. The question is whether this landmark ruling will affect the decades-long effort of the United Nations to promulgate a general, broadly accepted definition of ‘terrorism’. In that sense, the decision has the potential to have the same acceleratory effect on worldwide acceptance of a crime definition as the ICTY Interlocutory Decision in Tadić had with regard to war crimes committed in non-international armed conflicts. Whether this will materialize remains to be seen, though, especially since some serious objections can be raised against the Appeals Chamber's findings. These objections and the ensuing controversial nature of the decision may affect its authority. It is evident that this monumental decision merits close scrutiny.

In the following, two legal experts, Kai Ambos and Ben Saul, discuss the STL ruling and reflect on it critically. In the first part of his paper, Kai Ambos criticizes the Appeals Chamber's flexible stance on the principle of legality and its ‘international approach’ to interpreting Lebanese law. He argues that there is no reason to resort to international law. The alleged transnational nature of the terrorist offence or even its qualification as a threat to peace does not render international law applicable, not even as an interpretive tool. In the second part of the paper, Ambos rejects the Chamber's finding that there exists a customary international crime of terrorism. Instead, he argues that, at best, terrorism is a particularly serious transnational, treaty-based crime that comes close to a ‘true’ international crime but has not yet reached this status.

Ben Saul pursues Ambos's argument on the absence of customary international law in relation to the international crime of terrorism. He meticulously dissects the STL ruling and reviews the references to national and international criminal law to conclude that terrorism is not a customary international crime. He makes a compelling argument that the Appeals Chamber misjudged the available sources evidencing the international community's attitude to criminal liability for terrorism. The cited national legislation, judicial decisions, international and regional treaties, and UN resolutions do not, in his view, corroborate the finding that, nowadays, a customary crime of terrorism exists.

These two contributions jointly provide thought-provoking and stimulating ideas and comments. We are confident that they will further guide and inspire the international debate on the STL ruling and more broadly on the formation of customary international law, on the potential and limits of international judicial creativity, and on the status and need for an international definition of the crime of terrorism.