In many cases, during a criminal investigation, police officers need a search warrant to access your phone. They may be interested in looking at the browser history on your phone, reading your text messages, looking at social media messages, checking your location data and things of this nature. They can ask you for consent to unlock your phone, but if they do not get it, then they have to get a search warrant.
However, are there any ways that the police can access this information without serving a search warrant to you personally? There are, because you may have given some of this information to third parties. These third parties could then be approached by the authorities—perhaps with a warrant—and information may be turned over.
Why do third parties have your data?
The reason why a third party may have important evidence varies from case to case, but it is often because you have given consent by using their apps or platforms.
For instance, say that you back up your phone to a cloud server. Another company runs that service, and your pictures and videos may be stored on their servers, not just on your phone.
Or, for example, say that you sent messages using a social media app like Facebook or Reddit. You can send direct messages to other users, but those are not just stored on your phone. The company whose app you used to send the messages may also have access.
Furthermore, your phone may be tracking your location when you carry it. Does your cellphone provider have access to that location data, meaning that the police could get it even without unlocking your device?
This helps to show some of the complexities of handling search warrants and digital evidence, and it is important for those involved in criminal cases to understand their rights and defense options.