Doesn't the Fourth Amendment protect me from being searched?

No. The Fourth Amendment guarantees the right of people to be free from unreasonable searches and violations of privacy. The Fourth Amendment states, "The right of people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the person or things to be seized." To determine what might be unreasonable, a "legitimate expectation of privacy" must be established.