On the basis of information that respondent Santana had in her possession marked money used to make a heroin "buy" arranged by an undercover agent, police officers went to Santana's house where she was standing in the doorway holding a paper bag, but as the officers approached she retreated into the vestibule of her house where they caught her. When she tried to escape, envelopes containing what was later determined to be heroin fell to the floor from the paper bag, and she was found to have been carrying some of the marked money on her person. Respondent Alejandro, who had been sitting on the front steps, was caught when he tried to make off with the dropped envelopes of heroin. After their indictment for possessing heroin with intent to distribute, respondents moved to suppress the heroin and marked money. The District Court granted the motion on the ground that although the officers had probable cause to make the arrests, Santana's retreat into the vestibule did not justify a warrantless entry into the house on the ground of "hot pursuit." The Court of Appeals affirmed. Held:
1. Santana, while standing in the doorway of her house, was in a "public place" for purposes of the Fourth Amendment, since she was not in an area where she had any expectation of privacy and was not merely visible to the public but was exposed to public view, speech, hearing, and touch as if she had been standing completely outside her house. Thus, when the police, who concededly had probable cause to do so, sought to arrest her, they merely intended to make a warrantless arrest in a public place upon probable cause and did not violate the Fourth Amendment. United States v. Watson, 423 U.S. 411. P. 42
2. By retreating into a private place, Santana could not defeat an otherwise proper arrest that had been set in motion in a public place. Since there was a need to act quickly to prevent destruction of evidence, there was a true "hot pursuit," which need not be an extended hue and cry "in and about [the] public streets," and thus a warrantless entry to make the arrest was justified, Warden v. Hayden, 387 U.S. 294, as was the search incident to that arrest. Pp. 42-43.