I'm pretty sure I've heard that it was ruled that a smell is considered "in plain sight." For instance, if a police officer pulls you over, and smells some weed can he legally search you or the car? On the same note, if they have a dog at a place like an airport, and the dog smells drugs or a bomb, is it considered in plain sight? If someone could give me a link directly to the case law on this issue that would be great. 
