In the United States v. Leon case, the Fourth Amendment exclusionary rule should not be applied so as to bar the use in the prosecution's case in chief of evidence obtained by officers acting in reasonable reliance on a search warrant issued by a detached and neutral magistrate but ultimately found to be invalid. Pp. 905-925. (United States v. Leon, (1984) No. 82- 1771.) In view of the modification of the exclusionary rule, the Court of Appeals' judgment cannot stand in this case. Only respondent Leon contended that no reasonably well trained police officer could have believed that there existed probable cause to search his house. However, the record establishes that the police officer’s reliance on the state-court judge's determination of
