Suppose you are being arrested, did you realize that if you are being taken into custody the police have the right to search you and the immediate area around you? This is called Search Incident to Arrest. The original purpose of this was to protect the safety of the officer in question, and to prevent the suspect from destroying evidence. There is no probable cause requirement for this search, and it has been challenged and upheld repeatedly.

There is a new wrinkle these days. Police are using this precedent to examine the contents of your cell phone and any other personal electronics. Call histories, web browsing history, files, etc. All of this info is fair game and accessible. It's not a far leap to think that this will eventually include checking for bootleg music and software. After all it is a simple thing to inventory most electronic devices, and there are hefty fines and potential jail time for bootleg software and music.

Even more worrying your emails will be available if you retrieved them on your phone. Are you comfortable with Joe Flatfoot reading your mail out of context? What about passwords stored as internet cookies. If you save your password the last time you went to the online bank account, is that fairgame?

If you have a locked strongbox with you when arrested, the police can compel you to open it. If you have password protected your phone or encrypted the files on that phone, can they compel you to divulge your password?

This is a precedent currently being challenged, and bears watching. In the meantime, keep your phone fairly sanitized.