What principle was established in Katz v. United States (1967)?

The principle established in Katz v. United States (1967) is the concept of a "reasonable expectation of privacy." This landmark Supreme Court case fundamentally changed how courts evaluate privacy issues under the Fourth Amendment. In Katz, the Court ruled that the government's intrusion into a phone booth to overhear a conversation constituted a search, despite the fact that the booth was in a public place. The Court determined that individuals have a reasonable expectation of privacy in certain situations, which extends to their conversations and personal communications, even if they are occurring in public.

This ruling emphasizes that it's not just the physical invasion of property that constitutes a search; rather, the expectation of privacy that an individual has is equally important. This framework is critical for evaluating whether a specific action by law enforcement constitutes a violation of privacy rights, shaping subsequent interpretations of what constitutes reasonable privacy in various contexts.

Other aspects related to privacy, such as the definition of curtilage or limitations on thermal imaging, while significant, do not encapsulate the foundational shift brought about by this case regarding individual expectations of privacy. Thus, the reasonable expectation of privacy remains a cornerstone of modern privacy rights discussions in the United States.