The Court of Appeal’s recent decision in HKSAR v Yau Kai Fung [2026] HKCA 885 may prove to be one of the most significant developments in Hong Kong drug sentencing in recent years. Although the case itself involved relatively modest quantities of ketamine and cocaine, its wider importance lies in the Court’s reconsideration of how judges should sentence offenders found trafficking in more than one type of dangerous drug.
For many years, sentencing in so-called “cocktail drug” cases was shaped by the Court of Appeal’s decision in HKSAR v Chan Yuk Leong (CACC 318/2013). The central difficulty in such cases is straightforward: where an offender is found trafficking several different drugs, simply adding together the individual sentences for each drug can produce an unduly severe result, while treating all of the drugs as a single substance may understate the overall criminality involved.
To address this problem, the Court in Chan Yuk Leong endorsed what became known as the three cross-checking exercises : –
The first was the absurdity test, under which the court compared the proposed sentence with the sentence that would have been imposed if all of the drugs had consisted solely of the most serious substance involved. The second was the conversion test, which sought to convert different drugs into an equivalent quantity of a single “base drug” before applying one sentencing tariff. The third was the ratio test, which produced a weighted sentence by reference to the relative quantity and seriousness of each drug.
While these tests were originally intended as practical safeguards, they gradually became a prominent feature of sentence appeals. In some cases, substantial argument was devoted to competing mathematical calculations rather than to the offender’s actual role, culpability and conduct. As sentencing guidelines continued to evolve, this increasingly technical approach became difficult to reconcile with the broader sentencing framework developed by the Court of Appeal.
It was against this background that Yau Kai Fung came before the Court. By the time of that appeal, sentencing courts were already applying the structured methodology laid down in HKSAR v Herry Jane Yusuph [2021] 1 HKLRD 290, which requires consideration of the applicable guideline band, the offender’s role, aggravating and mitigating factors and the overall proportionality of the sentence. The Court also had the benefit of the revised drug sentencing guidelines introduced in HKSAR v Huang Ruifang (No. 3) [2025] 2 HKLRD 138.
The Court concluded that the older tests no longer sat comfortably with this modern framework. In particular, the absurdity and conversion tests were criticised as unnecessarily complicated and of limited practical assistance. Rather than assisting judges, they risked turning sentencing into an exercise in arithmetic. The Court therefore held that both tests should effectively be abandoned.
For practitioners, the decision provides welcome clarity. Sentencing submissions in cocktail-drug cases can now focus on the offender’s conduct and the applicable sentencing guidelines, rather than lengthy calculations under multiple tests.
In short, Yau Kai Fung marks the end of the “three-test era” established by Chan Yuk Leong. While the combined approach to sentencing multiple-drug offences remains intact, only the ratio test survives—and even then, only in a secondary role as a cross-check. The emphasis has shifted from mathematical exercises to a more structured and principled assessment of the offender’s overall criminality.