AZUIN BIN MOHD TAP v PUBLIC PROSECUTOR

Facts

Azuin bin Mohd Tap was convicted by a High Court judge on a capital drug trafficking charge and given the mandatory death penalty, in the decision reported as Public Prosecutor v Hashim bin Ismail and others [2023] SGHC 165. He did not dispute the charge at trial. His role was accepted to be that of a courier, but he received no certificate of substantive assistance, so the only question was whether he had diminished responsibility under s 33B(1)(b) read with s 33B(3) of the Misuse of Drugs Act, which would open an alternative sentence.

At trial the experts agreed he had opioid use disorder and stimulant use disorder. His expert, Dr Julia Lam, also diagnosed persistent depressive disorder, which the Prosecution's expert, Dr Kenneth Koh, rejected. The Judge preferred Dr Koh, found that the applicant and his sister had lied to Dr Lam about his mental condition, and gave her evidence no weight. He also held that, in any case, there was no substantial impairment, since the applicant said he trafficked because it was lucrative and would not do so for small sums.

The applicant appealed in CA/CCA 6/2022. By Court of Appeal / Criminal Motion No 48 of 2024, he sought leave to adduce two new expert reports: a psychiatric report by Dr Jacob Rajesh and a neuropsychological report by Ms Low Yung Ling. The Court of Appeal gave an ex tempore judgment on 27 February 2025.

Issues

1. Whether the two new expert reports met the materiality condition for admitting further evidence on appeal.
2. Whether evidence that conceded at least one limb of diminished responsibility could influence the appeal.
3. Whether obtaining new experts after trial to run new and inconsistent arguments amounted to expert shopping and an abuse of process.

Holding

The Court of Appeal dismissed the application for leave to adduce further evidence, on the sole basis that neither expert report was material to the appeal. It added that the applicant's conduct was expert shopping, which it held is conduct that amounts to an abuse of process.

Reasoning

The court applied the three conditions in Ladd v Marshall [1954] 1 WLR 1489, namely non-availability, materiality and reliability, noting that in criminal applications by an accused person the non-availability condition is applied in an attenuated way and assessed together with the other two. The fatal problem was materiality. Dr Rajesh diagnosed only moderate opioid use disorder and expressly accepted that it did not arise from one of the three causes recognised under s 33B(3)(b). Ms Low found the applicant to be of generally low intelligence but without any intellectual disability, so there was no abnormality of mind. As the alternative sentencing regime is only available where every limb of diminished responsibility is met, evidence conceding that one limb failed could not help the appeal.

The court then addressed expert shopping. At trial, the applicant's case depended on persistent depressive disorder; his own counsel's questions and Dr Lam's concessions made clear that the other two disorders were not said to impair him on their own. On appeal he appeared to be shifting to a new case that opioid use disorder alone was enough, and to a new attack on Dr Koh's assessment based on low intelligence that was never put to Dr Koh at trial. The court described this as expert shopping of the most egregious form. Using the appeal to try out different versions of a case after losing would undermine finality and the integrity of the trial process, the two rationales for the Ladd v Marshall conditions identified in AnAn Group (Singapore) Pte Ltd v VTB Bank (Public Joint Stock Co) [2019] 2 SLR 341. It found support in R v Foy [2020] EWCA Crim 270. The court made clear that new or even inconsistent defences on appeal are not barred outright, as Mohd Suief bin Ismail v Public Prosecutor [2016] 2 SLR 893 shows, but quite exceptional circumstances would be needed to allow a change of position backed by a new expert, and future applications of this kind could fail as an abuse of process.

Finally, even if the applicant had not abandoned his reliance on persistent depressive disorder, the new evidence was still immaterial. The Prosecution did not contest the two substance use disorders, and the real issue on appeal remained persistent depressive disorder, on which the new reports said nothing.

From the judgment