What significant issue was addressed in Katz v. United States?

Katz v. United States is a landmark Supreme Court case that addressed the issue of privacy and the Fourth Amendment's protection against unreasonable searches and seizures. The case involved federal agents who wiretapped a public phone booth used by Charles Katz, suspecting him of illegal gambling activities. The Court ultimately ruled that the use of wiretaps constituted a search under the Fourth Amendment, and thus required a warrant.

The decision underscored the principle that individuals have a reasonable expectation of privacy in their conversations, even in public places like a telephone booth. This ruling expanded the interpretation of the Fourth Amendment beyond just physical searches to include technological intrusions on personal privacy, setting a precedent for future cases involving electronic surveillance. Therefore, the significant issue at hand was indeed the use of wiretaps without a warrant, emphasizing the need for law enforcement to respect individuals' privacy rights in the face of new technologies.