3. Do the police have power to search and examine the digital content of a mobile phone found on the arrested person?
A police officer has power to do so if he has a warrant.
When it is not reasonably practicable to obtain such warrant before a search is conducted, the police officer must also have a reasonable basis for having to conduct the search immediately as being necessary (i) for the investigation of the 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 (ii) 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). Other than a cursory examination for filtering purpose, the scope of the detail examination of the digital contents of a phone should be limited to items relevant to the objectives.
In addition, a police officer should make an adequate written record of the purpose and scope of the warrantless search as soon as reasonably practicable after the performance of the search and 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 arrested person is under no legal obligation to unlock his password-protected mobile phone despite the request of the police officer.