HKSAR v. Chan Ka Lok

HCCC 121/2024

[2026] HKCFI 416

IN THE HIGH COURT OF THE

HONG KONG SPECIAL ADMINISTRATIVE REGION

COURT OF FIRST INSTANCE

CRIMINAL CASE NO 121 OF 2024

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REASONS FOR RULING ON ADMISSIBILITY OF
WHATSAPP MESSAGES

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INTRODUCTION

1.The Defendant, Chan Ka-lok, faces one count of “Trafficking in a dangerous drug”.  The evidence in issue comprises WhatsApp messages obtained from his iPhone.  The messages are divided into three categories:

(a)     Pre-arrest messages – exchanged before his arrest at approximately 14:30 on 28 June 2022;

(b)     Post-arrest, pre-CDO messages – exchanged between his arrest and the commencement of the Controlled Delivery Operation (“CDO”) at about 15:20 the same day; and

(c)     CDO messages – created during the CDO itself.

2.The Prosecution originally seeks to adduce categories (a) and (b).  It expressly does not seek to adduce category (c), accepting that the principles in HKSAR v Li Cheuk Wah [2024] HKCA 466 likely render such evidence inadmissible due to inherent unfairness.  The Defence objects to the admission of all categories, primarily on grounds of unfairness under Li Cheuk Wah.  

3.Relying on R v Kearley (1992) 95 Cr. App. R. 88, the defence further objects to the admissibility of those messages sent between the arrest and the commencement of the CDO (category (b)) on the ground that the mobile phone had already been seized by the Customs officers at the time of arrest at 1430 hours, and it was in their possession thereafter.  Those messages after his arrest were sent to him but unanswered anyway (one-way communication in the absence of the defendant) and was inadmissible as hearsay.

4.After careful consideration of the principles set out in Li Cheuk Wah and Kearley, the Prosecution concedes and now only seeks to admit the pre-arrest messages.  It does not seek to adduce any evidence created during and after the commencement of the CDO and those voice or text messages sent between arrest and the commencement of the CDO (at 15:20 hours) (categories (b) and (c)).

5.A key development is the Prosecution’s reliance on a search warrant dated 3 August 2022.  It contends that this warrant provides an independent and lawful basis for the admission of the pre-arrest messages, removing any taint of unfairness.

6.This ruling determines whether the pre-arrest WhatsApp messages are admissible.

RELEVANT AUTHORITIES

7.Three principal authorities govern the issues:

i.     HKSAR v Chan Kau Tai [2006] 1 HKLRD 400: This judgment held that there was a discretion to exclude as well as admit evidence.  The objective of the exercise of discretion was to ensure a fair trial of the accused took place.

(a)     First account must be taken by the court of any breaches of rights contained in the basic Law or the ICCPR;

(b)     Second, any breach would not automatically result in exclusion of evidence obtained in consequence of the breach.  The court still retained the discretion.  In considering fairness, the court must take a board view of the overall circumstances.  It must not just look at procedural fairness of the trial.  It was also entitled to look at the behavior of the investigating authority.  In this regard, there could be situations in which it would be such an affront to the public conscience or the integrity of the criminal justice system was so compromised that the court must step in and put a stop to it.  So while there was no discretion to refuse to admit relevant evidence on the ground that it had been obtained by improper or unfair means, the court could exclude evidence obtained by unfair means in circumstances where admission would have an adverse effect on the fairness of proceedings.

(c)     Third, the discretion involved a balancing exercise involving two competing interests, both facets of the public interest, on the one hand, protecting constitutionally guaranteed rights; and on the other, ensuring detection of crime and bringing criminals to justice.  Breach of constitutional rights was an important factor whose weight would depend mainly on the nature of the right involved and the extent of the breach.  So where the gravity of the breach was small but the crime a serious one, the public interest lean towards the latter, with the result that evidence obtained as a result of the breach would be admitted.  Also, when conducting the balancing exercise, the court must also have regard to the fact that some crimes by their nature surreptitious, not easily detected, and authorities were driven to resort to covet investigation technics.  

ii.     Sham Wing Kan v Commissioner of Police [2020] HKCA 186: This judgment addresses the common law power of search incidental to arrest, particularly concerning the digital contents of a mobile phone.  It holds that a warrantless search of an arrestee’s phone is permissible only when it is not reasonably practicable to obtain a warrant beforehand.  The power must be exercised for purposes truly incidental to the arrest (e.g. preserving evidence, protecting persons, investigating the offence) and is subject to proportionality scrutiny under the Hong Kong Bill of Rights and the Basic Law.

iii.     HKSAR v Li Cheuk Wah [2024] HKCA 466: This judgment establishes the core principle of inherent unfairness when the prosecution seeks to use against an accused evidence derived from his cooperation in a Controlled Delivery Operation, where the stated purpose of that operation was to apprehend others.  It creates a high barrier to the admission of such evidence, rooted in procedural fairness and the protection against self-incrimination through cooperation with the investigating authority. 

8.These cases operate in distinct but potentially overlapping spheres: Chan Kau Tai made it clear that any breach of right would not automatically result in exclusion of evidence obtained in consequence of the breach.  The court still retained the discretion.  The discretion involved a balancing exercise involving protecting constitutionally guaranteed rightsand detection of crime and bringing criminals to justice; Sham Wing Kan concerns the lawful parameters of seizing and searching a phone upon arrest and Li Cheuk Wah concerns fairness in the context of evidence obtained through cooperation in a specific investigative operation (the CDO).

APPLICATION TO THE FACTS

(a)      The Search Warrant Argument

9.The Prosecution’s submission that the search warrant “cures” any potential unfairness is superficially attractive but, upon close scrutiny, is fundamentally flawed.  It misunderstands the nature of the objection and the principles at stake.

10.The Defence objection is not solely, or even primarily, about the legality of the means of obtaining the evidence.  It is about the context and purpose for which the Defendant’s private information was first accessed and the fairness of using it against him thereafter.  The chronology is critical:

i.     The Defendant was arrested and, in the post-arrest period, was asked to participate in a CDO.

ii.     To facilitate the CDO, he signed PE Form, consenting to officers “check[ing] and see[ing]” his phone for the specific purpose of carrying out the CDO.  He provided his passcode.

iii.     Officers immediately accessed the phone, viewed its contents (including the pre-arrest WhatsApp messages), and used it to conduct the CDO.

iv.     Only later, on 3 August 2022, was a search warrant obtained.

11.On the evidence of Customs Senior Inspector Tsang, the officer-in-charge of the case (“the OC case”), before me this morning, the decision to apply for the warrant, and the information substantiating that application, derived from the initial, consensual access gained during the CDO process.  The warrant did not spring from an independent investigation; it was the formalisation of a seizure for which the groundwork was laid during the CDO.  As the Court of Appeal in Li Cheuk Wah emphasised, the unfairness lies in using or exploiting an accused’s cooperation for one purpose (catching others) to investigate and prosecute him. Such kind of behavior of the present investigating team although not necessarily evil, was nevertheless devious and would be unacceptable.  The subsequent warrant does not alter this fundamental character of the investigation.  To hold otherwise would allow the C&E Department to easily circumvent Li Cheuk Wah by a simple two-step process: obtain access via cooperation, then “regularise” it with a warrant.

12.Furthermore, the Defendant’s consent in the preliminary Form was limited in scope.  It was given for the purpose of the CDO, not as a general waiver permitting a forensic excavation of his private communications for evidence to be used in his own prosecution.  Using the access gained under this limited consent to mine for pre-arrest evidence is a significant and unfair expansion of the consent’s scope.  The OC case has also fairly conceded when he gave evidence that it is better to obtain a separate consent from the Defendant to allow the Custom officers to use the passcode given for a general search of the iPhone, knowing full well that the same passcode was initially given for the specific purpose of CDO only.  The OC case also told the court that normally after the warrant was obtained, the Defendant would be asked if he is willing to cooperate and give away his passcode for the purpose of searching the contents of the iPhone and if for whatever reason, the Defendant is unwilling to cooperate, he would need to send the iPhone to the C&E digital laboratory for further forensic examination.  According to his understanding, his colleague will then try their best to “break open” the iPhone by using a suitable software.  From his experience, the success rate for “breaking open” all different brands and models of mobile phones is only 40-50% so there is no reason to assume that even the Defendant refuses to allow the C&E to use the passcode for the purpose of a general search, the C&E must be able to gain access to the iPhone anyway.  The OC case also told the court that he believes he did not resort to the assistance by the digital laboratory in this case to gain access to the iPhone because they already have the passcode in hand albeit was given to them by the Defendant for CDO purpose only.

(b)      Distinction from Sham Wing Kan

13.Sham Wing Kan is distinguishable.  That case concerned the immediate post-arrest power to search a phone to preserve evidence or prevent danger.  Here, the initial access to the phone’s contents was not exercised under that common law power.  It was not a situation where officers, upon arrest, deemed it impracticable to get a warrant and searched the phone to secure evidence related to the arrest offence.  Rather, the phone was accessed later, as part of the CDO arrangement.  The legal justification proffered at the time was the Defendant’s consent for the CDO, not the common law power of search incidental to arrest.

14.Even if the Sham Wing Kan framework were applied retroactively, the Prosecution would struggle to show it was “not reasonably practicable” to obtain a warrant before accessing the phone post-arrest.  The Defendant was in custody, the phone was already seized as an exhibit.  The officers chose instead to embed its examination within the CDO process.  The subsequent warrant does not retrospectively create a “reasonable impracticability” that did not exist at the operative time.

(c)      Unfairness Under Li Cheuk Wah

15.The heart of the matter remains the principle from Li Cheuk Wah.  The CDO was presented to the Defendant as an operation to catch “Ah B” and the second accused person who later came to collect the parcel from the Defendant.  His cooperation – including providing his iPhone and passcode – was obtained on that basis.  There is no evidence he was given the specific, clear warning required by Li Cheuk Wah that he need not participate and that information obtained could be used against him.

16.To now use the WhatsApp messages – which came to light because of and during that cooperative framework – as proof of his mens rea is the epitome of the “inherent unfairness” the Court of Appeal sought to prevent.  It represents a breach of the understanding under which he cooperated and a misuse of the C&E power to secure evidence through cooperation which again is an unacceptable investigatory behaviour.

17.The timing of the messages’ creation (pre-arrest or post-arrest/pre-CDO) does not alter this analysis.  The unfairness infects the process of their discovery and seizure.  According to the evidence of the OC case, the pre-arrest messages were not discovered through an independent, lawful search incidental to arrest or later pursuant to the search warrant.  They were discovered because the Defendant, under the auspices of the CDO, allowed officers into his digital privacy in the iPhone.

CONCLUSION

18.For the reasons set out above, I find that the admission of the disputed pre-arrest WhatsApp messages – would be unfair to the Defendant within the meaning of Li Cheuk Wah.  The later procurement of a search warrant does not cleanse the evidence of this foundational unfairness, as the warrant was itself a product of the information gained through the unfair process in the first place.  According to Chan Kau Tai, the court could exclude evidence obtained by unfair means in circumstances where admission would have an adverse effect on the fairness of proceedings after carefully conducting a balancing exercise.

ORDER

19.The evidence in category (a) messages is therefore excluded in the exercise of the court’s discretion to ensure a fair trial.  The Defence objection is upheld.

Mr. John Charles Wright, Counsel-on-fiat, for the HKSAR

Mr. David MA, leading Ms. Renee CHENG, instructed by Cheung, Yeung & Lee, Solicitors, assigned by The Director of Legal Aid, for the defendant