Case Details
- Citation: [2025] SGCA 8
- Court: Court of Appeal (Singapore)
- Court/Case Number: Criminal Motion No 48 of 2024
- Date: 27 February 2025
- Judges: Sundaresh Menon CJ, Tay Yong Kwang JCA and Steven Chong JCA
- Applicant: Azuin bin Mohd Tap
- Respondent: Public Prosecutor
- Procedural Posture: Ex tempore judgment on an application to adduce further evidence in support of an appeal
- Lower Court Decision Referenced: Public Prosecutor v Hashim bin Ismail and others [2023] SGHC 165 (the “GD”)
- Sentence/Charge Context: Conviction on a capital charge of drug trafficking; mandatory death penalty imposed
- Key Substantive Issue Below: Whether the applicant suffered from diminished responsibility to qualify for an alternative sentencing regime under s 33B(1) of the Misuse of Drugs Act
- Fresh Evidence Sought: Two new expert reports (psychiatric report by Dr Jacob Rajesh; neuropsychological assessment by Ms Low Yung Ling)
- Core Outcome on Motion: Application dismissed
- Judgment Length: 18 pages, 5,155 words
- Legal Areas: Criminal procedure; appeal; adducing fresh evidence; diminished responsibility; sentencing
Summary
In AZUIN BIN MOHD TAP v Public Prosecutor ([2025] SGCA 8), the Court of Appeal dismissed the applicant’s criminal motion seeking leave to adduce further expert evidence in support of his pending appeal against the High Court’s rejection of his diminished responsibility defence. The applicant had been convicted of drug trafficking and sentenced to the mandatory death penalty. His defence below focused on whether he could be brought within the alternative sentencing regime for diminished responsibility under s 33B(1) of the Misuse of Drugs Act (Cap 185, 2008 Rev Ed) (“MDA”).
The Court of Appeal held that the proposed expert evidence was not material to the appeal because it did not overcome a critical deficiency identified by the trial judge: at least one of the statutory limbs for diminished responsibility was not made out. In addition to this primary ground, the Court expressed a broader concern that the applicant’s conduct amounted to “expert shopping” after an adverse decision, warning that such behaviour can constitute an abuse of process even in the criminal context where the stakes are high.
What Were the Facts of This Case?
The applicant, Azuin bin Mohd Tap, was convicted by a Judge of the General Division of the High Court on a capital charge of drug trafficking and sentenced to the mandatory death penalty. The sentencing framework was driven by the MDA’s mandatory sentencing regime for certain quantities of controlled drugs, subject to limited statutory exceptions. In this case, the applicant did not dispute the charge itself. Instead, he sought to qualify for an alternative sentencing outcome by invoking the diminished responsibility provisions in s 33B(1) of the MDA.
It was not disputed that the applicant’s role was limited to that of a courier. However, the Public Prosecutor did not issue a certificate of substantive assistance. As a result, the only sentencing pathway available to the applicant was diminished responsibility under s 33B(1)(b) read with s 33B(3) of the MDA. The trial judge therefore had to determine whether the applicant satisfied the statutory requirements for diminished responsibility, which include not only the existence of an abnormality of mind and substantial impairment of mental responsibility, but also a specific causal link to one of the recognised aetiologies set out in the statute.
At trial, the diminished responsibility question turned on expert psychiatric evidence. The prosecution’s expert, Dr Kenneth Koh (“Dr Koh”), and the applicant’s expert, Dr Julia Lam (“Dr Lam”), agreed that the applicant suffered from opioid use disorder and stimulant use disorder. Their disagreement concerned whether the applicant also suffered from persistent depressive disorder. The applicant’s case was that the combination of persistent depressive disorder, opioid use disorder, and stimulant use disorder caused substantial impairment of his mental responsibility at the time of the offence.
The trial judge rejected the defence. The judge found that the applicant did not suffer from persistent depressive disorder at the material time, largely because the judge disbelieved the factual account that the applicant and his sister had given to Dr Lam, which formed the basis of Dr Lam’s opinion. The judge preferred Dr Koh’s evidence, noting that the applicant’s and his sister’s accounts to Dr Lam were “in sharp contrast” to earlier accounts provided to Dr Koh shortly after arrest, including reports that “everything [was] ok” and that the applicant’s behaviour was “essentially normal”. The judge concluded that only one of the competing factual accounts could be true and placed no weight on Dr Lam’s evidence as a result.
What Were the Key Legal Issues?
The immediate legal issue before the Court of Appeal was procedural: whether the applicant should be granted leave to adduce further evidence on appeal. The Court applied the established framework for admitting fresh evidence on appeal, derived from Ladd v Marshall [1954] 1 WLR 1489 (“Ladd v Marshall”). Under that framework, the evidence must satisfy three conditions: (i) non-availability with reasonable diligence at the time of trial; (ii) materiality, meaning it would probably have an important influence on the result; and (iii) reliability, meaning it is credible.
However, the Court also had to consider how these conditions operate in criminal matters where an accused person seeks to adduce further evidence. The Court noted that the Ladd v Marshall conditions are not applied with full rigour in this context. In particular, the “non-availability” condition is treated as less paramount, though it is not dispensed with entirely; instead, it is assessed holistically in light of materiality and reliability. This meant the Court’s focus would be on whether the proposed evidence could realistically affect the outcome of the appeal.
A further, broader issue—though not strictly a separate legal test—was whether the applicant’s approach to obtaining expert evidence amounted to an abuse of process. The Court observed that the applicant appeared to be engaging in “expert shopping” by seeking new expert reports after an adverse decision below, potentially to lay the groundwork for new or inconsistent lines of argument on appeal.
How Did the Court Analyse the Issues?
The Court began by restating the governing principles for admitting further evidence on appeal. It emphasised that the Ladd v Marshall criteria provide the baseline structure. The Court then explained the modification applicable in criminal cases, referencing Soh Meiyun v Public Prosecutor [2014] 3 SLR 299 and Dzulkarnain bin Khamis v Public Prosecutor and another appeal and another matter [2023] 1 SLR 1398. The Court also relied on the line of authority clarifying that in criminal motions, the first condition (non-availability) is “less paramount” (as stated in AnAn Group (Singapore) Pte Ltd v VTB Bank (Public Joint Stock Co) [2019] 2 SLR 341 and Public Prosecutor v Mohd Ariffan bin Mohd Hassan [2018] 1 SLR 544). Nonetheless, the Court clarified in Miya Manik v Public Prosecutor and another matter [2021] 2 SLR 1169 that non-availability cannot be ignored; it must be evaluated holistically alongside materiality and reliability.
Applying these principles, the Court identified the applicant’s central difficulty: the proposed expert evidence was not material to the appeal. The Court examined the content of the two new reports sought to be adduced. The psychiatric report by Dr Jacob Rajesh (“Dr Rajesh”) expressed an opinion that the applicant suffered from an abnormality of mind in the form of moderate opioid use disorder, and that this substantially impaired his mental responsibility by causing a preoccupation with procuring drugs that led him to resort to drug trafficking to feed his addiction. However, Dr Rajesh acknowledged a critical statutory problem: the applicant’s opioid use disorder did not arise from one of the three recognised aetiologies under s 33B(3)(b) of the MDA. This acknowledgement was decisive because diminished responsibility under the MDA requires the abnormality of mind to be caused by one of the specified aetiologies.
In other words, even if Dr Rajesh’s report supported impairment, it did not satisfy the statutory causal requirement. The Court treated this as an insurmountable gap. The neuropsychological assessment report by Ms Low Yung Ling (“Ms Low”) similarly did not cure the statutory deficiency. Ms Low’s report addressed intellectual functioning and concluded that while the applicant was of generally low intelligence, he did not meet criteria for intellectual disability or disorder. The Court’s reasoning indicates that this evidence did not establish the required aetiological link under s 33B(3)(b), nor did it undermine the trial judge’s core findings in a way that would likely influence the appeal outcome.
Accordingly, the Court held that both reports accepted, in substance, that at least one limb of diminished responsibility was not made out. Because the statutory test is cumulative, evidence that fails to address a missing limb cannot be “material” in the Ladd v Marshall sense. The Court therefore dismissed the motion on the primary ground of immateriality.
Beyond this, the Court addressed a broader concern about process integrity. It observed that the applicant’s attempt to adduce further expert evidence appeared to be driven by “expert shopping”—that is, seeking different experts and producing reports that could support new arguments after the trial judge rejected the defence. The Court noted that it had previously cautioned against abuse of process in criminal proceedings, referencing Miya Manik. The Court took the opportunity to make clear that expert shopping of the kind it perceived in this case falls squarely within conduct that can amount to an abuse of process.
While the Court’s dismissal turned on immateriality, its commentary signals that courts will scrutinise not only whether fresh evidence meets the formal criteria, but also whether the application is being used strategically to re-run or repackage arguments that were already rejected, particularly where the new evidence does not address the statutory requirements or where it appears to be assembled after the fact to generate litigation advantage.
What Was the Outcome?
The Court of Appeal dismissed the applicant’s application for leave to adduce further evidence. The practical effect is that the appeal would proceed without the two new expert reports being admitted, and the applicant could not rely on those reports to attempt to satisfy the diminished responsibility requirements under the MDA.
The Court’s dismissal also carried a cautionary message: expert evidence obtained or deployed in a manner that resembles “expert shopping” may be treated as an abuse of process. Even where the stakes are high in capital cases, the Court indicated that it will not permit the appeal process to be used to manufacture new evidential foundations that do not materially address the statutory test or that reflect inconsistent, opportunistic litigation strategy.
Why Does This Case Matter?
This decision is significant for practitioners because it clarifies how the Court of Appeal will assess materiality in criminal motions to adduce fresh expert evidence. The Court’s approach underscores that materiality is not satisfied merely by presenting new expert opinions. Instead, the evidence must be capable of influencing the outcome by addressing the specific statutory elements that were missing or rejected below. Where the new expert reports concede that a statutory limb is not made out—particularly the aetiological requirement under s 33B(3)(b) of the MDA—admission is unlikely.
For lawyers handling diminished responsibility cases under the MDA, the case also highlights the importance of the causal/aetiological component. Expert reports that focus on impairment without establishing the required statutory origin of the abnormality of mind will not be sufficient. The Court’s reasoning demonstrates that the statutory test is structured so that failure on any one limb is fatal, and fresh evidence that does not close that gap is immaterial.
Finally, the Court’s discussion of “expert shopping” is a process-oriented warning that may affect how defence teams plan expert engagement after an adverse decision. The decision suggests that courts will scrutinise whether new expert evidence is being sought to genuinely address evidential deficiencies or whether it is being used to generate inconsistent alternative narratives on appeal. Practitioners should therefore ensure that any application to adduce further evidence is supported by a coherent explanation for why the evidence was not available earlier and, more importantly, how it directly bears on the legal elements in dispute.
Legislation Referenced
Cases Cited
- Ladd v Marshall [1954] 1 WLR 1489
- Soh Meiyun v Public Prosecutor [2014] 3 SLR 299
- Dzulkarnain bin Khamis v Public Prosecutor and another appeal and another matter [2023] 1 SLR 1398
- AnAn Group (Singapore) Pte Ltd v VTB Bank (Public Joint Stock Co) [2019] 2 SLR 341
- Public Prosecutor v Mohd Ariffan bin Mohd Hassan [2018] 1 SLR 544
- Miya Manik v Public Prosecutor and another matter [2021] 2 SLR 1169
- Nagaenthran a/l K Dharmalingam v Public Prosecutor and another appeal [2019] 2 SLR 216
- Public Prosecutor v Hashim bin Ismail and others [2023] SGHC 165
- [2021] SGCA 18
Source Documents
This article analyses [2025] SGCA 8 for legal research and educational purposes. It does not constitute legal advice. Readers should consult the full judgment for the Court's complete reasoning.