Warden v. Hayden 387 U.S. 294 (1976)
WARDEN v. HAYDEN 387 U.S. 294 (1976)
In Gouled v. United States (1921) the Court announced a rule that rings strange to the modern ear; when conducting an otherwise lawful search, police are authorized to search for contraband, fruits of crime, means and instrumentalities of crime, or weapons of escape, but they are not authorized to search for "mere evidence." The rationale for the mere evidence rule was never clear, but its main theme was that police could not take objects from an accused without asserting a superior property interest in the object seized. This requirement spurred judicial creativity in recognizing property interests and in broadly defining their scope.
In Warden v. Hayden the Supreme Court rejected this property-centered conception of fourth amendment jurisprudence. Police could seize evidence after all. Questions remained concerning the scope of searches for items previously regarded as mere evidence (such as diaries) and concerning the applicable standards for searches and seizures of "mere evidence" belonging to innocent parties.