Which case established that the Fourth Amendment does not protect open fields?

The case that established that the Fourth Amendment does not protect open fields is Oliver v. US. In this landmark decision, the Supreme Court held that the Fourth Amendment's protections against unreasonable searches and seizures do not extend to open fields. The Court reasoned that open fields are not considered "persons, houses, papers, and effects" under the Fourth Amendment. Consequently, law enforcement officers do not need a warrant to enter and search areas classified as open fields, even if those fields are within the curtilage of a home.

This ruling clarified the distinction between what is protected under the Fourth Amendment and what isn’t, emphasizing that the constitutional right to privacy primarily pertains to enclosed spaces rather than vast, open areas. In contrast, the other cases listed focus on different aspects of the Fourth Amendment and do not specifically address the issue of open fields. For example, Katz v. US deals with wiretapping and the expectation of privacy in communications, while US v. Dunn addresses the concept of curtilage, which is a close area to a dwelling, and Hester v. US confronts aspects of evidence obtained without a warrant but is not specifically centered on open fields as Oliver is.