Gan v HMA: The Refined Test for When a Section 28 Defence Must Go to the Jury in ‘Concerned in Supply’ Prosecutions

1. Introduction

In Choon Seng Gan v HM Advocate ([2025] HCJAC 32) the Scottish High Court of Justiciary was asked to quash a conviction for being “concerned in the supplying” of cannabis contrary to s 4(3)(b) of the Misuse of Drugs Act 1971 (“the 1971 Act”). Mr Gan, a London-based minibus driver, had transported two suitcases for a stranger, Mr Zheng, from Manchester to Glasgow. 74 vacuum-sealed packages of herbal cannabis (valued at £241,700) were discovered in the cases.

The appeal centred on alleged misdirections to the jury:

1. Did the trial sheriff err by failing to tell the jury that the Crown had to prove the appellant knew he was involved in an illegal supply of drugs?
2. Should the sheriff have directed the jury on the statutory “lack of knowledge” defence in s 28 of the 1971 Act, notwithstanding that defence counsel did not raise it at trial?

2. Summary of the Judgment

The Court (Lord Justice Clerk Beckett, Lords Doherty and Armstrong) dismissed the appeal. It held:

• The sheriff correctly instructed the jury that the Crown had to prove (i) that Mr Gan was knowingly involved in a supply operation of something, and (ii) that the “something” was in fact cannabis. The Crown need not prove that the accused knew the substance was an illegal drug.
• The absence of a specific direction on s 28(2) was a technical misdirection, because one strand of the appellant’s evidence — that he believed the suitcases merely contained personal belongings — potentially engaged the defence. Nevertheless, the misdirection favoured the accused and did not result in a miscarriage of justice.
• The case clarifies when a s 28 defence is “in play”: only where the accused accepts participation in a supply operation but denies knowledge, suspicion or reason to suspect that the goods are controlled drugs. A pure denial of any supply involvement does not invoke s 28.

3. Analysis

3.1 Precedents Cited and Their Influence

• Salmon v HM Advocate (1999 JC 67) — cornerstone authority on the interface between ss 4, 5 and 28. It established that knowledge of a supply operation is part of the actus reus, but knowledge that the goods are controlled drugs can be displaced only by the accused through s 28.
• R v McNamara (1988) 87 Cr App R 246 — English authority analysed in Salmon. Supported the notion that possession-plus-knowledge of “something” suffices, shifting ignorance-of-drug into s 28.
• Glancy v HM Advocate 2001 SCCR 385; Aiton v HM Advocate 2010 JC 154; and Hattie v HM Advocate 2022 JC 100 — all post-Salmon Scottish appeals refining jury directions in s 4(3)(b) cases. Each underscored that a simple denial does not trigger s 28.

The Court charted the doctrinal thread:

1. Salmon’s two-stage model: Crown must (a) prove knowing involvement in supply of “something”, and (b) prove the “thing” is the drug. If both proved, conviction follows unless the accused establishes a s 28 defence.
2. Glancy/Aiton confined s 28 to scenarios where the accused’s knowledge of the drug (not supply) is disputed. Denial of supply places the burden squarely on the Crown; s 28 is irrelevant.
3. Gan adopts this line but refines the test: a s 28 direction becomes necessary only where evidence shows (i) acceptance or proven existence of supply activity in which the accused is knowingly involved, and (ii) credible evidence that the accused did not know/suspect the substance was a controlled drug.

3.2 The Court’s Legal Reasoning

“An appropriate direction would have been that if the jury concluded that the appellant was knowingly involved in a supplying operation, he should nevertheless be acquitted if he did not know, suspect or have reason to suspect that the suitcase contained a controlled drug or if the jury were left in reasonable doubt about that.” – Lord Justice Clerk Beckett

Key reasoning points:

1. Knowledge of Supply v. Knowledge of Drugs. These are distinct mental elements. The Crown must prove only the former; the latter may be negatived by s 28.
2. Role of Jury Directions. Because the trial sheriff repeatedly told the jury to acquit if any defence evidence created reasonable doubt, the lack of an explicit s 28 direction did not mislead. Indeed, the sheriff gave an erroneously generous incrimination direction, further tilting in the appellant’s favour.
3. Miscarriage of Justice Test. A conviction will stand despite a technical misdirection unless it materially prejudiced the accused. The Court held that, given the weight of circumstantial evidence and the jury’s rejection of Gan’s account, a correct s 28 direction would have made no difference.

3.3 Likely Impact of the Decision

Gan consolidates Scottish appellate guidance into an easily applied rule of practice:

“Where the defence case is mere denial of any supply involvement, s 28 is not in play. If, however, the accused accepts or the evidence proves participation in a supply chain yet asserts ignorance of the drug nature of the item, trial judges must put s 28(2) to the jury.”

Consequences:

• Jury Charges. Sheriffs and judges will now routinely canvass with counsel, mid-trial if necessary, whether the evidential foundation for a s 28 direction has emerged.
• Defence Strategy. Solicitors must plead their case theory with precision: “pure denial” or “supply-but-no-drug-knowledge”. The former preserves the Crown burden; the latter invites a s 28 burden (now evidential only after R v Lambert).
• Prosecutorial Proof. The Crown remains spared from proving an accused’s awareness of the illicit character of the goods, but must prepare for s 28 rebuttal wherever evidence of innocent carriage surfaces (e.g. couriers, removal services).
• Clarity on Incrimination. The decision echoes Flanagan v HMA that incrimination rarely fits s 4(3)(b) offences; judges should avoid confusing the jury by giving it where legally irrelevant.

4. Complex Concepts Simplified

Section 4(3)(b) – “Being Concerned in Supplying”

Not just selling drugs yourself; it covers any practical involvement (storage, transport, financing, lookout, packaging) in a supply chain.

Section 28 Defence

A statutory “lack of knowledge” shield. If the Crown proves the basic offence, an accused can still be acquitted by showing he did not know, suspect, or have reason to suspect the critical fact (usually that the substance was a controlled drug). Since Lambert, the burden is evidential (raise a realistic possibility), not legal (prove on balance of probabilities).

Incrimination

A special defence alleging “the real culprit was X, not me”. In s 4(3)(b) cases it seldom exculpates because multiple actors can be guilty.

Miscarriage of Justice Test (Scotland)

The appellate court asks whether the misdirection materially affected the jury’s verdict. A favourable misdirection to the accused rarely meets that threshold.

5. Conclusion

Gan v HMA does not revolutionise substantive drug-supply law, but it crystallises a procedural point of high practical value: trial judges must only charge a jury on s 28 where the accused’s position entails knowledge of supply but ignorance of drugs. Where the defence is outright denial of any supply role, s 28 is otiose. By distinguishing these scenarios, the Court streamlines jury instructions, diminishes risk of appealable misdirection, and provides clearer sign-posting for both prosecution and defence in complex supply-chain prosecutions.

Key takeaways:

• The Crown’s burden: prove the accused knowingly took part in a supply operation of “something”, and that “something” was the drug libelled.
• S 28(2) is engaged only when the accused’s knowledge (or suspicion) of the drug itself is in issue; ignorance of the supply operation is an ordinary defence resolved by reasonable doubt.
• Erroneous directions favourable to the accused rarely vitiate a conviction unless they conceal a material direction unfavourable to him.