On 6 November 2015 the Appeals Chamber of the International Criminal Court (ICC) wrote a new chapter in the saga on the situation ‘with respect to the 31 May 2010 Israeli raid on the Humanitarian Aid Flotilla bound for Gaza Strip’. The Chamber, by 3 votes to 2, dismissed the Prosecutor’s appeal against the Pre-Trial Chamber’s “Decision on the request of the Union of the Comoros to review the Prosecutor’s decision not to initiate an investigation”. 
From a procedural point of view, it all began in May 2013, when a State Party to the ICC, namely, the Union of the Comoros, referred the Israeli raid on the aid flotilla consisting of vessels registered in Greece, Comoros and Cambodia to the Court. Then, on 6 November 2014, the ICC Prosecutor, Fatou Bensouda, announced her decision under article 53(1) ICC Statute not to proceed with an investigation. She argued that, pursuant to article 17(1) (d) ICC Statute, none of the cases that could potentially arise from this situation would have been of sufficient gravity as to require further action by the Court. In July 2015, following an application filed by the Union of the Comoros, Pre-Trial Chamber I, for the first time since the Court’s establishment, asked the ICC Prosecutor to reconsider her decision. Judge Kovács issued a partly dissenting opinion.
Some criticised the pronouncement of the Pre-Trial Chamber and described it as ‘a deeply problematic and extremely dangerous decision — nothing less than a frontal assault on the OTP’s prosecutorial discretion’. What is certain is that the whole procedural history, including the Appeals Chamber’s most recent decision, shows how delicate the issues at stake are; they might have significant implications in terms of both international, and ICC internal, politics. However, one could look at all these decisions as the lens through which to measure the state of ICC system’s health.
First, the Rome Statute provides for a well-balanced system of relations between the diverse institutional actors involved, including the Prosecutor and the Pre-Trial Chamber. The Appeals Chamber’s decision, along with its procedural background, has simply proved how all actors played their statutory role and contributed to keeping the ICC as a living, but well-balanced, system.
Second, despite the fact that the drafters of the ICC Statute are usually deemed to have successfully created a statute that complies with the certainty of law – as required by the principle of legality, this procedural querelle stems from a lack of clarity in the relevant statutory provisions, namely, articles 53(3)(a) and 82(1)(a) ICC Statute. This is also reflected in the Appeals Chamber’s narrow majority which last 6 November adopted the decision in question. However, the Appeals Chamber’s judges have contributed to the maintenance of the ICC system, being called upon to decide on an issue which the ICC Statute does not regulate expressis verbis. This shows how, despite the drafters’ efforts to draft a comprehensive Statute, the ICC judges nevertheless exercise quite a significant interpretative function which, in certain cases, might be such as to be considered a creative interpretation.
In particular, before the Appeals Chamber, the Prosecutor argued that, pursuant to article 82(1)(a) ICC Statute, she could appeal the Pre-Trial Chamber’s decision because, from a substantive perspective, the Pre-Trial Chamber’s decision constituted a decision on admissibility, even if it did not fulfil the formalities of an admissibility decision. The Prosecutor had, in fact, based her decision not to proceed with an investigation exclusively on the absence of the required gravity under article 17 (1)(d) ICC Statute. As a consequence, Pre-Trial Chamber I, in its decision, had focused on admissibility as well.
On the other hand, the Union of Comoros and the victims’ representatives considered that the Pre-Trial Chamber’s decision was not a decision on admissibility and, therefore, it could not be appealed by the Prosecutor. Indeed, since according to article 82 (1)(a) ICC Statute, the Prosecutor is only allowed to appeal against decisions on jurisdiction and admissibility, the possibility for the prosecutor’s appeal to be considered at all depended on the very nature of the Pre-Trial Chamber’s decision. Should this have been considered a decision on admissibility, it would also have been regarded as a ‘final’ decision (subject to appeal) whose legal nature would have then turned out to be a review decision binding on the prosecutor. Put otherwise, the statutory lacuna consisting of the absence in article 82(1)(a) ICC Statute of an express provision for an appeal of any Pre-Trial Chamber’s decision pursuant to article 53(3)(a)  could have opened a breach in the system of checks and balances regulating the relations between the Prosecutor and the Trial Chamber. This would have attributed more power to the Trial Chamber.
The Appeals Chamber however affirmed as follows:
In the Appeals Chamber’s assessment, the distinction between the powers of the Pre-Trial Chamber under article 53 (3)(a) and (b) reflects a conscious decision on the part of the drafters to preserve a higher degree of prosecutorial discretion regarding decisions not to investigate based on the considerations set out in article 53 (1)(a) and (b) of the Statute. Indeed, under article 53 (3)(a) of the Statute, the Prosecutor is obliged to reconsider her decision not to investigate, but retains ultimate discretion over how to proceed. 
As a result, the majority dismissed the Prosecutor’s appeal against the Pre-Trial Chamber’s decision, having considered the latter as not being a decision on admissibility. In this regard, it is interesting to note that the two dissenting judges, Judge Silvia Fernández De Gurmendi and Judge Christine Van Den Wyngaert, have instead underlined how the Court’s previous ‘jurisprudence does not address the novel circumstances at hand in which the Prosecutor decides not to open an investigation in a situation on grounds of inadmissibility of potential cases within that situation.’  They thus concluded that ‘[a] novel question […] arises in relation to which neither article 18 nor article 19 is applicable’.  Accordingly, they concluded that ‘[t]his novel approach requires the focus to be on the subject-matter of the impugned decision in order to determine whether the essence of the decision pertains to admissibility.’ 
Therefore, by filing an appeal relying on article 82 (1)(a) ICC Statute, Bensouda successfully led the Appeals Chamber to clarify an aspect which, so far, has been considered to be ‘completely unclear’.  In so doing, the Court has provided an answer to the two underlying questions on the legal nature and the consequences, vis-à-vis the Prosecutor, of a decision issued by the Pre-Trial Chamber pursuant to article 53(3)(a) ICC Statute. In other words, with the Appeals Chamber’s decision to dismiss the Prosecutor’s appeal, the Prosecutor obtained the express recognition that, under article 53(3)(a), the Prosecutor retains the ultimate discretionary power to decide whether or not to proceed with an investigation of a situation referred to the Court by either a state party or the UN Security Council; the Pre-Trial Chamber cannot impose a duty upon the Prosecutor to re-open an investigation.
It remains to be seen whether, following her reconsideration, the Prosecutor will decide to open an investigation over the facts at issue or whether she will reach the very same conclusions that she came to in November 2014. With respect to the latter scenario, Spain might provide Bensouda with a new ground to support her decision. Indeed, in relation to the very same facts of the Comoros situation, Spanish judge Jose de la Mata asked to the relevant national authorities to be notified if ever Netanyahu and six other Israeli officers are going to be present within the Spanish territory. Under the new Spanish ley de justicia universal, judge de la Mata cannot proceed with the investigations until the relevant people find themselves in Spain. In future, should the circumstances arise that would trigger the proceedings in Spain, the ICC Prosecutor might rely on article 17(1)(a) and consider that a State which has jurisdiction over cases that could possibly arise from the situation has already been conducting investigations or prosecutions.
In conclusion, the complex procedural history relating to the Comoros situation shows that the system of checks and balances provided by the ICC Statute does work correctly. Indeed, one should see the tension between the Prosecutor and the Pre-Trial Chamber as a signal of the ICC being in good health, and not vice versa. In the present case such a tension has led the judges from the Appeals Chamber to interpret the Statute so as to fill a legislative lacuna. After all, the function of a judge, especially at the international level, still requires quite a significant creative effort.
 ICC-01/13-1-Anx1. See also ICC-01/13-1-Anx2, p. 2.
 See, e.g., Antonio Cassese, The Human Dimension of International Law: Selected Papers of Antonio Cassese (OUP 2008) 517-8; Cassese (ed), The Oxford Companion to International Criminal Justice (OUP 2009) 459.
 See, e.g., Flavia Lattanzi and William Schabas (eds), Essays on the Rome Statute of the International Criminal Court (Vol. I, Editrice Il Sirente 1999) 215.
 See, e.g., the Pre-trial interpretation of ‘self-referrals’ and their compatibility with article 14 ICC Statute. William Schabas, The International Criminal Court: A Commentary on the Rome Statute (Cambridge University Press 2010) 311.
 Situation on Registered Vessels of the Union of the Comoros, the Hellenic Republic and the Kingdom of Cambodia, (Decision on the admissibility of the Prosecutor’s appeal against the “Decision on the request of the Union of the Comoros to review the Prosecutor’s decision not to initiate an investigation”) ICC-01/13 OA, Appeals Chamber (6 November 2016) at 17.
 cf Situation on Registered Vessels of the Union of the Comoros, the Hellenic Republic and the Kingdom of Cambodia, (Joint Dissenting Opinion of Judge Silvia Fernández De Gurmendi and Judge Christine Van Den Wyngaert attached to the Decision on the admissibility of the Prosecutor’s appeal against the “Decision on the request of the Union of the Comoros to review the Prosecutor’s decision not to initiate an investigation”) ICC-01/13-51-Anx, Appeals Chamber (6 November 2016) at 12.
 Situation on Registered Vessels of the Union of the Comoros, the Hellenic Republic and the Kingdom of Cambodia (n 5) at 55.
 ibid at 59.
 Situation on Registered Vessels of the Union of the Comoros, the Hellenic Republic and the Kingdom of Cambodia (n 6) at 24.
 ibid at 26.
 William Schabas, An Introduction to the International Criminal Court (4th Edition, Cambridge University Press 2011) 258.
 See, Schabas (n 4) 340.
 None of the victims was in fact a Spanish citizen.
 Stephen Macedo, Universal Jurisdiction: National Courts and the Prosecution of Serious Crimes Under International Law (University of Pennsylvania Press 2006) 73.