Groningen Journal of International Law

International Law Under Construction

The ‘Mental Disorder’ Defence in Prosecutor v Ongwen


Marina Fortuna


On 4 February 2021 the Trial Chamber IX of the International Criminal Court (ICC) issued its judgment in the Prosecutor v. Dominic Ongwen. The case concerns the events which occurred in Northern Uganda between 1 July 2002 and 31 December 2005 for which Ongwen was charged with 70 counts of war crimes and crimes against humanity, 66 of which he was found guilty for.

During the proceedings, the Defence Counsel raised the defence of mental disease (or defect), provided for in Article 31(1)(a) of the ICC Statute as a ground for excluding Ongwen’s responsibility. The judgment’s course of proceedings and the Trial Chamber’s reasoning addresses important procedural and evidentiary issues concerning the ICC’s mental disease defence. This contribution discusses two of them: the procedural issues concerning the burden and standard of proof and the evidentiary issues concerning the expert reports and psychological/psychiatric examination.

1. The Law

According to Article 31 (1)(a) of the ICC Statute, if a person suffers from a mental disease preventing them from “appreciat[ing] the unlawfulness or nature” of their conduct, or their “capacity to control the conduct to conform to the requirements of the law”, they shall not be held criminally responsible.

The applicability of this defence requires the psychiatric/psychological examination of the defendant, governed by the Rules of Procedure and Evidence (RoP&E). Rules 113 and 135 provide that “[t]he Pre-Trial Chamber [Trial Chamber in the case of Rule 135(1)] may, on its own initiative or at the request of the Prosecutor, the person concerned, or his or her counsel, order that a person having the rights in article 55, paragraph 2, be given a medical, psychological or psychiatric examination”. To assess whether such an examination is warranted, the Pre-Trial/Trial Chamber will take into account the nature and purpose of the examination, as well as the Defendant’s consent to such an examination.

2. The Case

a. Burden and Standard of Proof

One procedural issue that arose during the proceedings concerned the burden and standard of proof. According to Article 66 (2) of the ICC Statute, ‘the onus is on the Prosecutor to prove the guilt of the accused’. Article 66 (2) should be read together with Article 67 (1)(i) which establishes the right of the defendant “not to have imposed on him or her any reversal of the burden of proof or any onus of rebuttal”. Relying on these two provisions, in January 2019,  the Defence Counsel submitted a request to the Trial Chamber to clarify the burden and standard of proof applicable to Articles 31(1)(a) and (d). It was argued that in the case of defences, the Prosecution is under the obligation to disprove each element of the defence beyond reasonable doubt (para 2 of the request).

From the standpoint of the Prosecution, the burden of proof does not lie with any party; nevertheless, there must be substantial evidence presented in support of the ground of exclusion raised by the Defence. This conclusion is warranted by the provisions of Rule 79(1) (b) of the RoP&E, which compels the Defendant to provide the Prosecution with the names of the witnesses or any other evidence he/she intends to rely upon when raising grounds for the exclusion of responsibility. Regrettably, neither the Decision of the Trial Chamber, nor the Judgment clarified this matter. The Trial Chamber only noted that there is no specific provision in the Statute relating to the burden and standard of proof under Article 31, and for this reason, the general provisions of the Statute apply (paras 85-93, 2455). Additionally, it pointed out that it is up to the Chamber to make a finding concerning mental disease or defect and further implied that the evidence precedented during the proceedings was sufficient to make a pronouncement on this judicial fact (para 2456).

b. Expert Reports and their Probative Value

Another point of contention was the content of the psychological/psychiatric expert reports, and the conclusions drawn from them. Five experts presented their reports on the question of whether Ongwen suffered from any mental disorder/defect during the time of the acts he was found guilty of having committed. As opposed to the experts of the Prosecution, the Defence experts’ reports concluded that Ongwen suffered from severe depression, post-traumatic stress disorder (PTSD), dissociative disorder, obsessive compulsive disorder and suicidal ideation at the time of the commission of the crimes (para 2450).

The Trial Chamber questioned the reliability of the Defence experts’ reports, especially the methods employed. Relying on the assessment of the Prosecution experts, the judgment notes that the reports did not apply scientifically validated methods (para 2532) as the Defence experts used open-ended questions instead of structured rating scales (para 2532). Moreover, the reports were criticised for having heavily relied on the clinical interview and neglected the other evidence from the trial (para 2535). Other objections to the methodology included the lack of a structured examination of the criteria of each diagnosis (para 2524), the reliance on the outdated DSM-IV instead of the DSM-V Manual (para 2533), and the lack of objectivity due to the fact that the experts made recommendations concerning the mental health of the defendant at the time of the proceedings (para 2528 & 2529). However, perhaps what weighed most heavily against the reliability of the Defence experts’ reports were the contradictions contained in the reports themselves and the contradictions between the observations in the reports and the statements made during the testimony (para 2536), as well as the danger of malingering (paras 2558-2568). For these reasons, the Trial Chamber found that “Ongwen did not suffer from a mental disease or defect at the time of the conduct relevant under the charges” (para 2580).

3. Discussion

The assessment of the mental condition defence in Ongwen raises some concerns regarding the procedural and evidentiary framework of the ICC, many of which have been anticipated by legal scholars (Krug, 2000; Radosavljevic, 2013). Firstly, the conclusions of the Trial Chamber concerning the burden or the standard of proof of mental disease or defect are unsatisfactory. Unlike domestic jurisdictions, neither the ICC Statute, nor the RoP&E, contain any provision which would constitute a drawback having considerable impact on the Defendant’s case. For instance, in Prosecutor v. Delalić et. althe ICTY ruled that diminished or lack of mental capacity was to be proven by the Defendant. However, the standard that it applied was the balance of probabilities, a less stringent test than the standard of beyond reasonable doubt. The ICC Statute and its RoP&E currently leave the Defendants in the dark on this point.

Secondly, the judgement reveals the difficulties that international criminal law judges face in evaluating psychological/psychiatric evidence. One important question concerns the conditions that psychological/psychiatric evidence should fulfil in order to be considered reliable. There are currently no such provisions or guidelines under international criminal law (as probative value is assessed by the judges freely). Yet the question concerning conditions is particularly important for cases where the Court is presented with conflicting evidence, as in Ongwen.

To guarantee the enjoyment of the privilege against self-incrimination, the ICC Statute allows psychological/psychiatric examination only with the consent of the Defendant. However, as shown in Ongwen, sometimes this can be to the detriment of the Defendant. The Trial Chamber, in its assessment of the Defence experts’ reports, heavily relied on the rebuttal reports submitted by the Prosecution experts, which excluded mental disorder (or defect) and instead relied on other evidence, such as witness testimony presented during the trial and video footage. The question arises as to whether a psychological/psychiatric expertise conducted without a clinical interview should carry the same weight as one including such an interview. While the danger of malingering is always present, it appears at least counterintuitive for an expertise on the mental state of the defendant to not be, first and foremost, based on a clinical interview. In this regard, an amendment of the procedural and evidentiary provisions of the ICC, to include conditions that a psychological/psychiatric expert report should satisfy in order to be admissible in Court, would further the interests of justice.

Another problem raised in Ongwen, and that can be expected to arise in future cases, concerns the lack of agreement among the Prosecution and Defence experts on the methods used in their clinical assessment. In particular, the experts in Ongwen disagreed on whether or not psychometric tests should have been conducted to avoid malingering. The methodology used by the experts seemed to have been an important factor in the decision of the Trial Chamber. Yet isn’t it too much to expect of forensic experts who are dealing with the appreciation of another individual’s  subjective state of the mind to proceed in exactly the same ways, especially given the diversity in schools of thought in the field? While the lack of consistency within a report may definitely cast a shadow of doubt on its credibility, and the reliance on the specific methods used as a way to question the reliability might be too much to ask given the lack of consensus on this issue in the field (Dattilio et. al, 2011). This is especially the case when the experts are not preliminarily presented with specific requirements/expectations on the contents of the report (especially, whether or not an expert should consider corroborating evidence) and method of the expertise — an issue which can be remedied by adopting a set of guidelines on this matter.

In conclusion, Ongwen demonstrates the urgent need for refining the procedural and evidentiary rules concerning the mental disease defence under international criminal law. This refinement, in the form of clear conditions for expert reports to confirm their credibility, is important not only to ensure that justice is done towards the Defendants, but also to safeguard the legitimacy of the ICC itself.

Marina Fortuna LLM is a PhD researcher in the TRICI-Law project at the University of Groningen. Her PhD research focuses on the interpretation of customary international law in the practice of international courts and tribunals. Marina’s area of interest and research includes customary international law, interpretation, international courts and tribunals, impartiality and reasoning of international judges and the intersection between international law and psychology/psychiatry.

2 thoughts on “The ‘Mental Disorder’ Defence in Prosecutor v Ongwen

  1. Thanks for the information you have provided through your blog.


  2. Pingback: The Psychological Assessment of the Defendant in the Ongwen Case: An Interview with Prof. Joop de Jong | Groningen Journal of International Law

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