Andrew Cantor has a commentary in USA Today's CyberSpeak called "New digital camera? Know how, where you can use it." He points out the rat's nests of legal problems that can arise from shooting on government property and in certain work environments like doctor's offices. Further complications arise from publishing the photographs.
So before you go out and snap pictures of Area 51 or your work, check out the article. It could keep you out of court!
