Does the Fourth Amendment define exactly what an unreasonable search is? How did the Supreme Court define the meaning of search in the case Katz v. United States, and how did this meaning differ from Olmstead v. United States? What did the court deem as being the necessary elements and a lawful search, and is physical intrusion necessary to fall within the meaning of a search? The following will define exactly what an unreasonable searches, and analyze the differences of interpretation of search in both Katz and Olmstead.