Granted, this is Canada, but American legal cases have danced all around this issue, too. And while you might not think you have anything to hide of a criminal nature, are you sure there's nothing that wouldn't be, at least, embarrassing on your phone? In an email? A text message? A photo?
Cops can search mobile phones—only if they’re not password-protected
Court of Appeal for Ontario says Toronto cops acted in good faith.
