The task of determining appropriate sentences for the international crimes of genocide, crimes against humanity and war crimes is unquestionably difficult. Yet, in spite of their complex and heinous nature, the sentencing of these crimes is largely unregulated and has been left to the discretion of the judges of the international criminal courts and tribunals. It is no surprise, then, that disparities in the various sentences do arise.

The author examines this difficult and unregulated area of international criminal law in order to identify common themes and inconsistencies in the sentencing practice of the chambers of the two ad hoc tribunals – the International Criminal Tribunal for the former Yugoslavia (ICTY) and the International Criminal Tribunal for Rwanda (ICTR) – with the purpose of providing suggestions for a more consistent sentencing practice in the International Criminal Court (ICC). The publication supports its doctrinal study of the jurisprudence of the ad hoc tribunals with an empirical analysis of factors that have influenced the sentencing practice of the tribunals. It is one of the few publications that is entirely devoted to the topic of sentencing in international criminal justice.

The first two chapters provide a comparative overview of the laws of sentencing international crimes at both international and national level. The author explains that both systems have employed the principle of proportionality i.e. the principle that the sentence must be proportionate to the gravity of the crime. Yet, whereas the statutes of the two ad hoc tribunals and the Rome Statute of the ICC contain only general provisions on sentencing, in the domestic legislation of the national systems examined – of England and Wales, France, Germany, Italy, Spain and the USA – ranges of penalties and/or minimum and maximum sentences are attached to each crime. The author addresses various arguments which suggest that the absence of precise penalties or penalty ranges in international criminal law is contrary to the principle of nulla poena sine lege, or the prohibition of retroactive punishment, and, in doing so, argues convincingly that the principle will not be violated if the penalties for international crimes have not been prescribed precisely by statute. The author posits that the principle will be respected as long as the statutes provide a penalty of imprisonment for the specific crime in question.

Sentencing jurisprudence of the ad hoc tribunals is the focus of chapter three. In the majority of cases before these tribunals, the judges have imposed a single sentence for the totality of findings regarding the criminal conduct of the accused and have not specified single penalties for each specific charge. The author argues against this practice, advocating instead an approach to sentencing where a specific penalty is meted out in respect to each finding of guilt and in relation to each crime. Her approach is convincing and would certainly provide for more transparency and consistency in sentencing. Furthermore, it finds support in Article 78(3) of the Rome Statute of the ICC which, unlike the statutes of its predecessors (the ad hoc tribunals), requires the Court to pronounce a separate sentence for each crime and then a joint sentence specifying the total period of imprisonment.

The Achilles' heel of chapter three is the author's doctrinal analysis of the question of whether there is a hierarchy of the international crimes of genocide, crimes against humanity and war crimes. The author argues that a ranking of international crimes would ensure greater transparency and consistency in sentencing since sentences would be meted out in accordance with the crime's position in the hierarchy, genocide attracting the longest sentences and war crimes the shortest. Yet, in order to support her argument that genocide is intrinsically more serious than crimes against humanity, she has selected early ICTR and ICTY Trial Chamber jurisprudence (p. 148) and has failed to acknowledge the subsequent Appeals Chamber judgments that have rejected any such hierarchy (i.e. Prosecutor v. Kayishema and Ruzindana (ICTR-95-1-A), Judgment, 1 June 2001, para. 367 and Prosecutor v. Stakić (IT-97-24-A), Judgment, 22 March 2006, para. 375). In arguing that there should be a hierarchy between crimes against humanity and war crimes, the author, to her credit, nevertheless does acknowledge that appellate jurisprudence has rejected such a notion (p.148).

Chapter four contributes to a very sparse collection of empirical studies of sentencing in international criminal law. The author's statistical analysis of influential factors in the ICTY and ICTR sentencing practice reveals the extent to which each factor has impacted on the length of sentences. While the author may have failed to provide relevant doctrinal support for the existence of a hierarchy of crimes, her statistical research reveals that, in practice, individuals convicted of genocide do, in fact, receive the longest sentences, and those convicted of war crimes receive the shortest sentences. On the basis of this research, she concludes that there is, in practice, a hierarchy of international crimes.

The author is somewhat hasty in concluding (from her statistical analysis of the average length of sentences per crime) that there is a hierarchy of international crimes. She does not mention the significant fact that most individuals convicted of genocide have been high-level offenders responsible for large-scale killings, whereas most individuals convicted exclusively of war crimes have been low- to middle-ranking individuals. The rank of the individual and the scale of the commission of the crimes also contribute to the gravity of the crime and consequently the length of the sentence. It may well be that the presence of these additional factors alongside convictions of genocide, or the absence of these factors in convictions of war crimes, and not so much the intrinsic gravity of the crime itself, contribute to convictions for genocide receiving the longest sentences while convictions for war crimes receive the shortest.

The author's quantitative analysis of sentencing data provides for some interesting conclusions. There are high correlations between the length of sentences and the individual's leadership level, abuse of authority and type of participation – as well as the scale of the crime. On the other hand, there are low correlations between the length of sentences and modes of liability, the age of the accused and the composition of the judicial bench. The author's analysis also shows that while aggravating factors have, for the most part, been applied consistently, the converse is the case with mitigating factors. Her analysis reveals a number of inconsistencies in the sentencing practice of the ad hoc tribunals, in particular at the ICTY, and in relation to the discounting of sentences on the basis of plea bargains. This provides a strong basis for the argument she makes in her final chapter – that a set of guiding principles would contribute to greater clarity and consistency in sentencing.

Chapter five focuses on the sentencing system of the ICC. At the time of publication, the permanent court had not yet handed down a judgment so the author's analysis of the sentencing process before the ICC is confined to an examination of the relevant provisions within the Rome Statute and the Rules of Procedure and Evidence. The author suggests that the Rules provide a significant step towards creating a pre-established range of penalties by providing a general maximum term of imprisonment of 30 years and, in addition, the possibility of imposing life imprisonment in particular circumstances. She underscores the matter that while the Rules contain a list of non-exhaustive factors which may improve consistency in sentencing practice, there are still substantial gaps in relation to the application of these factors, and, in particular, with regard to the relative weight attributable to each factor.

The inconsistencies that have been examined in the previous chapters on the sentencing practice of the ad hoc tribunals and the statutory regime of the ICC prompt the author, in her final chapter, to make various suggestions that may contribute to greater consistency and transparency in future sentencing practice. The author lists various non-exhaustive factors that may guide the sentencing chambers in their assessment of the gravity of the crime and in relation to aggravating or mitigating circumstances. In particular, she cautions against the practice of giving substantial mitigating weight to guilty pleas as this would detract from a sentence that reflects the gravity of the crime. She additionally recommends the establishment of indicative ranges of sentences for the classes of crimes of genocide, crimes against humanity and war crimes, as well as for the underlying offences of these international crimes and for the different forms and degrees of participation of the accused, yet leaves open the question as to how these various ranges should be calculated. These suggestions are, by the author's own admission, undeveloped, and are merely intended to provide a platform for future research into the ways in which a more consistent sentencing practice may be achieved. She can be credited for not suggesting an overly rigid and regulated sentencing system and for, instead, being sensitive to the need for a sentencing system that is flexible enough to accommodate the varied circumstances of each particular crime.

The book's inclusion of both doctrinal and empirical research provides a balanced account of sentencing in international criminal law. It will be of assistance to practitioners, academics and students of the discipline.