As a result of recent court cases, it is now legal in California and some other areas of the United States for law enforcement officers to search your cell phone upon arrest without a warrant. An article on Ars Technica provides an explanation of the law and instructions and tips for securing your phone and protecting yourself. Even if you live in an area where these laws do not affect you, it’s still a good idea to ensure the data on your phone is secure, should it fall into the wrong hands.
Last week, California’s Supreme Court reached a controversial 5-2 decision in People v. Diaz (PDF), holding that police officers may lawfully search mobile phones found on arrested individuals’ persons without first obtaining a search warrant. The court reasoned that mobile phones, like cigarette packs and wallets, fall under the search incident to arrest exception to the Fourth Amendment to the Constitution.
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On the other hand, if you are arrested with a mobile phone in your possession but not immediately associated with your person, police may not search your phone without a warrant once you’ve been taken into custody and your phone is under police control.
The takeaway from Diaz, therefore, is that you should store your mobile phone in your luggage, footlocker, or in some other closed container that’s not on your person, particularly when driving an automobile
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Therefore, if you care about your privacy, password-protecting your smartphone should be a no-brainer. Better yet, you should ensure your smartphone supports a secure implementation of full-disk encryption. With this method of encryption, all user information is encrypted while the phone is at rest. While it isn’t absolutely foolproof, full-disk encryption is the most reliable and practical method for safeguarding your smartphone data from the prying eyes of law enforcement officers (and from wrongdoers, like the guy who walks off with your phone after you accidentally leave it in a bar.)
Why you should always encrypt you smart phone via Lifehacker