Regardless of your age, the law recognizes that you have a certain amount of privacy. For example, your boss can’t search your purse or your wallet. The same is true of your cell phone - your texts are private like your journal or diary. However, if your boss provided you with the phone for work purposes, your supervisor could look through your texts. If the police are conducting an investigation they could also read your messages, with or without a search warrant, depending on the circumstances. Bottom line: don’t incriminate yourself - be very careful of what you say so that a statement is not misinterpreted as a threat or sign that you’re involved with criminal activity. Since this is a new and developing area of law, challenges based on expectation of privacy will be decided on a case-by-case basis.
Update: In June, 2008 a federal court ruled that there is an expectation of privacy in personal emails and text messages at work. Unless you give your boss permission in advance or at the time of the request to read them, federal law recognizes your privacy rights. [see Quon v. Arch Wireless Operating Co., Inc., 9th Circuit Court of Appeals, June 18, 2008].
