I recently moved to Los Angeles with my girlfriend, and my parents visited this weekend. Over dinner we discussed the California Supreme Court ruling which held that police officers don’t need a warrant to lawfully search mobile phones of arrestees.

All four of us own a smartphone, but I was the only one who encrypted password protected mine. So I obnoxiously brandished my Android device to demonstrate how easy it is to swipe a simple pattern to turn the phone on.

My girlfriend, a UCLA MBA candidate, scoffed that it was inefficient and not worth her time. But I countered that the split-second motion quickly becomes effortless. On the other end, my parents thought they had nothing to hide. (Have I taught these people nothing!?)

For the more cynical among us, Ryan Radia at the Ars Technica blog presents a thorough analysis of the relevant court cases impacting your smartphone privacy rights. He also lays out simple strategies that can protect your mobile device from police searches, even if you’re under arrest.

His tips should be common sense to Flex Your Rights fans.

While the [Fourth Amendment’s] search incident to arrest exception gives police free rein to search and seize mobile phones found on arrestees’ persons, police generally cannot lawfully compel suspects to disclose or enter their mobile phone passwords. That’s because the Fifth Amendment’s protection against self-incrimination bars the government from compelling an individual to divulge any information or engage in any action considered to be "testimonial"—that is, predicated on potentially incriminating knowledge contained solely within the suspect’s mind.

As such, if you are arrested or detained by a law enforcement officer, you cannot lawfully be compelled to tell the officer anything other than your basic identifying information—even if the officer has not read you the Miranda warning. Exercising your right to remain silent cannot be held against you in a court of law, nor can it be used to establish probable cause for a search warrant.

However, if you voluntarily disclose or enter your mobile phone password in response to police interrogation, any evidence of illegal activity found on (or by way of) your phone is admissible in court, regardless of whether or not you’ve been Mirandized.

If you’ve read this far and your smartphone is still not password protected, do it now!