Published online by Cambridge University Press: 22 April 2022
Argued October 17, 1967.Decided December 18, 1967.
Mr. Justice CAPERS delivered the opinion of the Court.1
We are not precisely told how Charles Katz, the petitioner, came to the FBI’s attention as someone involved in illegal gambling. But clearly by early 1965, the FBI considered the petitioner a person worth keeping an eye on. What we are told is that starting around February 4, 1965, FBI agents began tailing the petitioner, and continued tailing him for about two weeks. Their surveillance of the petitioner, presumably without his knowledge, revealed that the petitioner had a daily habit of making telephone calls from a particular row of telephone booths on Sunset Boulevard in Los Angeles. Further investigation, presumably through the telephone company, revealed that the petitioner’s calls were placed to a number in Massachusetts, which number the FBI traced to a known gambler. Armed with this information, but lacking a warrant, the FBI secretly placed a recording device on top of the bank of phones the petitioner had been using.