Semayne's Case. "A man's home is his castle" case from 1604.
Olmstead v. United States, 277 U.S. 438 (1928). This was an early rejection by the Supreme Court of Fourth Amendment rights in telephone conversations on the grounds that wiretaps do not constitute a physical search, and nothing is actually seized.
Katz v. United States, 389 U.S. 347 (1967). This decision effectively reversed Olmstead and established a reasonable right of privacy in electronic communications, on the grounds that "the Fourth Amendment protects people, not places."
Terry v. Ohio, 392 U.S. 1 (1968) "stop and frisk"