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Obtaining Warrants to Search Mobile Phones: Commentary on Sham Wing Kan v Commissioner of Police [2020] HKCA 186

Commentary by Adrian Lo

In Sham Wing Kan v Commissioner of Police [2020] HKCA 186, the Court of Appeal (CA) delineated the circumstances and procedures under which a warrantless search of digital contents of a mobile phone could lawfully be conducted by law enforcement officer upon arresting a suspect.  The principle of requiring judicial warrants where “reasonably practicable” were argued by Dr Gerard McCoy SC and Albert N B Wong.


The CA held that the power to conduct such search was a specie of the common law power which entitled law enforcement authority to procure evidence of the crime committed, to prevent its destruction and to protect officers of law enforcement and the public.[1] The source of power was common law, but not s.50(6) of the Police Force Ordinance (Cap.232) (PFO) which was concerned with procuring evidence only.[2]

As mobile phones differed from other objects that might be found on an arrestee’s person, the CA considered how common law in Hong Kong should be developed, in the context of searches of digital data in mobile phones incidental to arrest.[3] The CA noted that the developments would not prejudice any rights of a data subject to pursue complaints or seek remedies under the Personal Data (Privacy) Ordinance (Cap. 486).[4]

The CA rejected a categorical exclusion of warrantless mobile phone searches in favour of a test which confined such searches to situations when it was not reasonably practicable to do so after a warrant was obtained.[5] The CA preferred the “reasonable practicality” test as it was familiar to the law enforcement, and had been applied consistently in cases of warrantless searches, including searches of premises.[6]

In terms of the scope of any warrantless searches, the CA held that the following criteria were sufficiently clear and circumspect and the safeguards adequate:[7]

  • The law enforcement officer must have a reasonable suspicion that the person arrested (and subjected to the search) had committed an offence;
  • The scope and purpose of the search must be truly incidental to the arrest in question. The officer must have a reasonable basis for having to conduct the search immediately as being necessary: (1) for the investigation of offence(s) for which the person was suspected to be involved, including the procurement and preservation of information or evidence connected with such offences; or (2) for the protection of the safety of persons (including the victim(s) of the crime, members of the public in the vicinity, the arrested person and the police officers at the scene).
  • Whilst an officer would need to access the phone generally for cursory filtering examination, he should limit the scope of the detailed examination of its digital contents to relevant items by reference to the said criteria.
  • A further requirement by way of documentation of the purpose and scope of the warrantless search, the officer should make an adequate written record of the same as soon as practicable after the performance of the search. A copy of the written record should be supplied forthwith to the arrested person unless doing so would jeopardize the ongoing process of criminal investigation.

The CA concluded that the conferment of such power was compliant with Article 14 of the Hong Kong Bill of Rights and Article 30 of the Basic Law.[8]


Courts would in future need to determine circumstances in which the pre-condition of “reasonable impracticability” would be satisfied, and in doing so would build upon existing authorities including those dealing with searches of premises, etc.[9]  The CA in making no order as to costs of this appeal between the respondent and the 2nd Interested Party noted that the key findings in the case was that the common law in Hong Kong on mobile phone search should develop by reference to the concept of “reasonable practicability” and the “proportionality requirement” as per the position taken by the 2nd Interested Party.[10]

For planned law enforcement operations concerning known suspects, it would be expected that search warrants of mobile phones ought to be obtained beforehand under s.50(7) of the PFO as it would very likely be reasonably practicable to do so.[11] This should be similar to cases involving the search of premises.[12] The CA confirmed that magistrates had power to issue a warrant to authorize the search of the digital contents of the mobile phone under s.50(7) of the PFO.[13] Section 50(7) construed purposively allowed the search of a mobile phone to be treated as a search of a “place”, and electronic data or files in it as “document[s] or portion thereof or extract therefrom”.[14]

The position would be more complicated in situations where it was impossible to identify the suspect before the arrest. The CA appeared impressed by evidence that auto-lock or remote erasure functions of modern mobile phones might pose a risk of destruction of or obstruction to access to evidence in the time needed to obtain a warrant even after the mobile phones were seized. As such, the objective of prevention of “destruction” of evidence might justify warrantless search of mobile phones whose functions would “obstruct” access to evidence within minutes.[15]

“Reasonable practicability” in this context might potentially be different from that of a search of physical premises which could not auto-lock and auto-erase. This followed from the common ground before the CA that a magistrate did not have the power to compel a person to give the police the password to unlock his mobile phone or other electronic devices, and the Commissioner of Police’s acceptance that refusal to give such a password to the police would not constitute an offence of obstruction of a police officer in the due execution of his duty.[16]

One could expect the concept of “reasonable practicability” would change with the state of technology available to law enforcement authorities. Technological developments might lead to stronger encryption of data stored in mobile phones. However, there would also likely be more powerful techniques developed to decrypt and access such data. Where law enforcement authorities were equipped with devices to access data in particular models of mobile phones, it would unlikely be not reasonably practicable to first seize the mobile phones and then obtain a warrant.

The concept of “reasonable practicality” would embrace a wide range of factors in addition to urgency. The CA preferred to leave the precise factors to be considered to Courts tasked with fact-the-fact reviews.[17] It did accept however that the seriousness of the suspected offence could be one of the relevant factors to the assessment.[18]

Another facet would be the nature the evidence which the law enforcement officer wished to obtain in the warrantless search. The CA noted two types of evidence that might be relevant to investigation of an offence:[19]

  • The 1st type was concerned with the fact that the defendant made a particular phone call which happened to incriminate him;
  • The 2nd type was concerned with evidence which, by its very content, inculpated the defendant in the crime itself (e.g. admissions or incriminating photographs).

A warrantless search for materials of the 1st type did not involve a direct intrusion into suspects’ private communications. Depending on the circumstances, it might be easier to justify.[20]

Going Forward

Going forward, where reasonably practicable the police would be expected to obtain warrants to search mobile phones. There is typically only a narrow window before an arrestee’s mobile phone is powered-off or screen-locked.[21]Practically, the common law power of warrantless searches is unlikely to be exercised often. Therefore, Courts are likely to be faced with questions concerning judicial warrants to search mobile phones. These issues might arise in the context of an application to the magistrate who issued the warrant to have it set aside, an application to the Court of First Instance for judicial review against the magistrate’s decision to issue the search warrant, or a civil action for injunction to restrain use of the documents seized and to procure their return or for damages.[22] Seizing and searching mobile phones unless authorized by common law or statutory powers might constitute torts of trespass and conversion.

Since the CA mobile phone as a place, and the electronic data or files contained in it as “documents”,[23] it is likely that just as a search warrant regarding a premises must specify the premises to. be searched, a search warrant would have to identify the particular mobile phone to be searched. The information required to be included in a search warrant under s.50(7) of the PFO have been explained in K v Commissioner of Police [2020] 1 HKLRD 606. There is no prescribed form for a search warrant under s.50(7). The warrant must contain the matters to which empowering provision itself refers:[24]

  • It must be an authorisation directed to the police;
  • It must specify the premises to be searched;
  • It must specify the offence that has been committed or reasonably suspected to have been committed or to be about to be committed or to be intended to be committed, to the investigation of which the articles sought are likely to be of value;
  • It must indicate the articles which are sought; and
  • It must show that the magistrate is satisfied there is reasonable cause to suspect that there is in the specified premises such articles likely to be of value to the investigation.

Another issue of contention might be whether there is a right to have the warrant produced on demand.  K[25] suggests there is no such right.  On the other hand, in the context of a warrant issued under s.48 of the Competition Ordinance (Cap.619), Zervos J in Re Competition Commission [2020] HKCFI 988 seemed to have taken the view that a warrant ought to be provided to the occupier of a premises so as to enable the recipient to know and understand its purpose and the powers conferred under it, with sufficient particulars.

Lee Wing Ho (HCAL 132/2020) brought a judicial review action against warrants which authorized police to enter an office at the police headquarters where Lee’s devices were stored, along with around 50 devices and mobile phones seized from other arrestees. A similar claim was brought by Lau Wai Lun (HCAL 150/2020). A potential issue might be whether a warrant which identified the particular room where the devices are situate could authorize a search of the data in the devices.[26] In light of the judicial gatekeeping role highlighted in Sham [2020] HKCA 186, at §105, that: “In processing an application for such warrant, a judicial officer must bear in mind the judicial gatekeeping role discussed under Section B3 in the judgment of Keen Lloyd”, the sheer breadth of the warrants granted might well call into question whether all material information had been fairly placed before the judicial officer discharging his duty of assessing the proportionality of the warrants requested in the circumstances.

Wong Chi Fung brought a judicial review action questioning whether police had power to “hack” his password-protected phone purportedly under a search warrant when he refused to give police the password. The Court will likely have to explore interesting issues as to whether a warrant under s.50(7) of the PFO[27] could authorize law enforcement to use technology to access data in password-protected devices and whether this might infringe the right to remain silent.

More recently, an application for judicial review brought by Martin Lee Chu Ming (HCAL 1396/2020 represented by Albert N B Wong) is also expected to further refine the constitutionally compliant procedures in which the the Commissioner Police can retain the phones; apply for search warrants; the particularity of the terms of the warrants; and the jurisdiction of the Magistrate to entertain applications to set aside what are ex parte warrants on an inter partes basis.  See Recent News.


[1] Sham Wing Kan v Commissioner of Police [2020] HKCA 186, at §103

[2] Sham [2020] HKCA 186, at §160

[3] Sham [2020] HKCA 186, at §104

[4] Sham [2020] HKCA 186, at §181

[5] Sham [2020] HKCA 186, at §§149, 206

[6] Sham [2020] HKCA 186, at §204

[7] Sham [2020] HKCA 186, at §§187-188, 199, 218

[8] Sham [2020] HKCA 186, at §219

[9] e.g. Keen Lloyd v Commissioner of Customs and Excise [2016] 2 HKLRD 1372, HKSAR v Indra Agus Setiawati [2018] 3 HKC 394, HKSAR v McCall Howard Kenneth & anor [2018] 3 HKC 61,

[10] Sham [2020] HKCA 502, at §§16, 18

[11] Sham [2020] HKCA 186, at §77

[12] Sham [2020] HKCA 186, at §204 (“the test [the CA] propose to adopt in Hong Kong, reasonable practicality, is a concept familiar to our law enforcement officers and has been applied consistently”)

[13] Sham [2020] HKCA 186, at §166

[14] Sham [2020] HKCA 186, at §§163-165

[15] See Sham [2020] HKCA 186, at §121 and Section D3 of the Judgment

[16] Sham [2020] HKCA 186, at §35; c.f. specific powers in the Securities and Futures Ordinance (Cap.571) discussed in Cheung Ka Ho Cyril v SFC and anor [2020] 1 HKLRD 859

[17] Sham [2020] HKCA 186, at §77 (“Ultimately, it is a matter of common sense evaluation. A planned operation including arrest (with ample time to obtain a warrant in advance) is different from an officer acting spontaneously on the spot where an ongoing crime is taking place. Also the nature of the offence involved is relevant. Whilst warrantless search may be necessary in dynamic and serious crimes, there will not be such need with less serious offences. It would be best to leave it to the judge presiding at the criminal trial to determine on the admissibility of evidence with a full grasp of the facts and operational details in accordance with well-established principles.”

[18] Sham [2020] HKCA 186, at §214

[19] Sham [2020] HKCA 186, at §151

[20] Sham [2020] HKCA 186, at §151

[21] Sham [2020] HKCA 186, at §129

[22] K v Commissioner of Police [2020] 1 HKLRD 606, at §48

[23] Sham [2020] HKCA 186, at §164-165; R v Vu [2013] 3 SCR 657 and R v KZ (2014) ABQB 235 referred to

[24] K [2020] 1 HKLRD 606, at §46

[25] K [2020] 1 HKLRD 606, at §25

[26] Legal challenges filed after Hong Kong police obtain warrants to search seized digital devices (Hong Kong Free Press, 15 January 2020) ( (accessed at 26 April 2020); Hong Kong protests: High Court test for warrants that let police search phones (SCMP, 13 January 2020) ( (accessed at 26 April 2020)

[27] PFO s.50(7)(a): “… if necessary to break into or forcibly enter such… place and to search…”

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