Trevor Wan on Contesting Collateral Challenge: HKSAR v Chow Hang Tung (2024) 27 HKCFAR 71 (Judicial Review)

"Contesting Collateral Challenge: HKSAR v Chow Hang Tung (2024) 27 HKCFAR 71"
Trevor Wan
Judicial Review
Published Online: December 2024

Introduction: 

1. A collateral challenge exposes to legal scrutiny a public law act or decision in proceedings the primary object of which is not to impugn the validity of that act or decision. The public law challenge, rather, is ‘collateral’, ‘indirect’, or ‘incidental’ to the main issue under determination, which may be the liability or guilt of the defendant. As a collateral challenge is asserted outside the parameters of conventional judicial review, it is neither subject to nor encumbered by the procedural peculiarities that underpin the latter, thus rendering it an ‘exception’ to the well-recognised rule of procedural exclusivity in O’Reilly v Mackman. In the criminal context, a collateral challenge typically contests a public law act, the lawfulness of which constitutes an essential ingredient of the offence with which the defendant is charged, relying on for example the familiar grounds of illegality, irrationality, and procedural impropriety. If successful, the collateral challenge will undermine the prosecution’s case and potentially lead to an acquittal.

2. The doctrine of collateral challenge was recently considered by the Hong Kong Court of Final Appeal (CFA), the apex court of the jurisdiction, in HKSAR v Chow Hang Tung. In a split decision by a narrow margin of three-to-two, a majority of the CFA reaffirmed the principles governing the availability of collateral challenge in criminal proceedings laid down in R v Wicks and Boddington v British Transport Police, which are rooted in statutory interpretation. Furthermore, the CFA explicitly recognised a discrete category of collateral challenge, where the challenge stems not from statutory non-compliance or conventional public law grounds (i.e. ordinary collateral challenge), but incompatibility with constitutional provisions in the Basic Law and Hong Kong Bill of Rights, the Special Administrative Region’s statutory charter of rights incorporating the International Covenant on Civil and Political Rights (i.e. constitutional collateral challenge).

3. While the defendant in the end fell short of escaping conviction, the judgment...

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