Katz v. United States established that electronic surveillance generally requires what?

• A. A warrant
• B. Consent
• C. Probable cause
• D. A search warrant only in certain cases

Answer: (A)

Electronic surveillance implicates the Fourth Amendment's protection of privacy, and Katz v. United States extended that protection to phone and other electronic conversations by recognizing a reasonable expectation of privacy in such communications. Because that privacy interest exists, intercepting a private conversation generally requires a warrant issued by a judge based on probable cause. A warrant provides the legal authorization and specific limits the government must respect when conducting surveillance.

Consent can remove the need for a warrant if a valid party with authority agrees to it, and there are narrow exceptions (like exigent circumstances). But absent consent or one of those exceptions, the default rule established by Katz is that you need a warrant to conduct electronic surveillance. A stand-alone probable cause finding without a warrant isn’t enough, and saying it’s only required “in certain cases” doesn’t fit the general rule Katz set—that electronic surveillance is a search that usually requires a warrant.