## Facts

- Yip Chiu-Cheung was a serving Hong Kong police officer who covertly entered an agreement with an American undercover drug enforcement agent to transport heroin from Hong Kong to Australia.
- According to the plan, the heroin would be delivered in Australia, thereby committing the substantive offence of drug trafficking under both Hong Kong and Australian law.
- Unknown to Yip, the purported co-conspirator was, in truth, posing as a willing participant solely to gather evidence. The agent never intended that any heroin should actually be shipped or sold.
- Yip nevertheless took preparatory steps consistent with implementation of the scheme and was subsequently arrested and charged with conspiracy to traffic in a dangerous drug.
- At trial, Yip argued that there could be no “meeting of minds,” and thus no conspiracy, because the agent’s private, lawful purpose was to frustrate rather than further the contemplated crime. The trial court rejected that submission and convicted him.
- On appeal to the Court of Appeal of Hong Kong, and ultimately to the Judicial Committee of the Privy Council, Yip reiterated that the conspiracy was void for impossibility and for absence of genuine bilateral intent.

## Issues

1. Does a conspiracy exist where one ostensible party is an undercover agent who, lacking genuine criminal intent, never truly assents to the execution of the crime?
2. If the substantive offence is in fact incapable of completion because of the covert agent’s contrary purpose, does that factual impossibility constitute a defense to the charge of conspiracy?
3. More broadly, is liability for conspiracy contingent on the practical possibility of completing the planned crime, or does it rest on the defendant’s own mens rea and perceived agreement?

## Decision

- The Privy Council dismissed the appeal and restored the conviction.
- Their Lordships held that the essence of conspiracy in English criminal law is the defendant’s agreement, accompanied by an intention that the offence be carried out. The offence is complete once the agreement and requisite intent exist; execution is not required.
- Yip possessed the necessary mens rea. He believed he had entered a genuine criminal pact and intended to advance it. The fact that his apparent partner secretly lacked that intention did not erase Yip’s subjective criminal purpose.
- The Board emphasised that impossibility founded on extraneous facts—here, the covert status of the agent—does not negate conspiratorial liability. The critical inquiry is whether the defendant intended that the substantive offence be committed, not whether it can in fact occur.
- Consequently, an undercover operation does not provide a shield for the culpable party who agrees to traffic drugs and takes steps toward that unlawful end.

## Legal Principles

- Conspiracy is an inchoate offence designed to punish the danger created by concerted criminal intention. It crystallises upon formation of the unlawful agreement, irrespective of subsequent events.
- Factual impossibility is no defense. Where the substantive crime cannot be carried out because of facts unknown to the conspirator (e.g., the supposed partner’s secret opposition, lack of actual drugs, malfunctioning weapon), liability remains.
- Legal impossibility may, by contrast, exculpate—for example, where the agreed conduct, if performed, would not amount to an offence at all. The present case involved an act that would plainly be criminal (heroin trafficking), so legal impossibility was irrelevant.
- The case illustrates the asymmetric nature of conspiracy: a defendant can be guilty even when the other apparent conspirator is innocent or immune (as agents provocateurs typically are). What matters is the defendant’s belief in the mutual arrangement.
- Public policy supports this approach. Criminal law seeks to deter collaborative wrongdoing at its formative stage. To allow undercover agents to nullify liability would frustrate that protective objective.
- The decision aligns with earlier authorities (e.g., R v Siracusa; R v Anderson) confirming that one-sided intention suffices where the defendant thinks the agreement is real.

## Conclusion

R v Yip Chiu-Cheung reaffirms that conspiracy focuses on the defendant’s own agreement and intent. A covert agent’s lack of criminal purpose and the resulting factual impossibility do not bar conviction. The ruling thereby fortifies the preventive function of conspiracy law and clarifies that the offence is committed the moment a defendant, believing the agreement genuine, intends the crime to be carried out.


R v Yip Chiu-Cheung [1995] 1 AC 111