Olmstead v. United States (1928) holds that the warrantless tapping of telephone wires did not constitute an unconstitutional search and seizure, since there was no entry of the defendants' houses or offices and the evidence was secured by hearing. Lewis v. United States (1966) holds that it is not unconstitutional to admit evidence obtained by an undercover officer invited into the defendant's home based on the officer's misrepresentation of his identity. Hoffa v. United States (1966) holds that the fourth amendment does not protect a wrongdoer's misplaced belief that a person to whom he voluntarily confides his wrongdoing will not reveal it. Katz v. United States (1967) holds that the warrantless electronic surveillance of conversations held in a public phone booth was unconstitutional, since the privacy expectations of the suspect were involved. United States v. White (1971) holds that just as the law gives no protection to the wrongdoer whose trusted accomplice is or becomes a police agent, neither should it protect him when that same agent obtains recorded or transmitted conversations later offered in evidence. United States v. Russell (1973) concludes that it is only when the government's deception of a suspect actually implants the criminal design in the defendant's mind that entrapment occurs. Dissenting opinions are included. Case footnotes.