In his famous dissent in Olmstead v. United States, Supreme Court Justice Louis Brandeis in 1928 called the right to be left alone the most comprehensive of rights and the right most valued by civilized men. He was referring to the right to be left alone from the government — a right that today we call privacy.
Olmstead was involved in bootlegging, and the feds tapped his phones without any search warrants. The Supreme Court, which had never recognized the right to privacy, permitted the use of the overheard conversations as evidence in his criminal trial.