Franks v. Delaware

Mr. Justice Blackmun delivered the opinion of the Court.

This case presents an important and longstanding issue of Fourth Amendment law. Does a defendant in a criminal proceeding ever have the right, under the Fourth and Fourteenth Amendments, subsequent to the ex parte issuance of a search warrant, to challenge the truthfulness of factual statements made in an affidavit supporting the warrant?

In the present case the Supreme Court of Delaware held, as a matter of first impression for it, that a defendant under no circumstances may so challenge the veracity of a sworn statement used by police to procure a search warrant. We reverse, and we hold that, where the defendant makes a substantial preliminary showing that a false statement knowingly and intentionally, or with reckless disregard for the truth, was [*156] included by the affiant in the warrant affidavit, and if the allegedly false statement is necessary to the finding of probable cause, the Fourth Amendment requires that a hearing be held at the defendant's request. In the event that at that hearing the allegation of perjury or reckless disregard is established by the defendant by a preponderance of the evidence, and, with the affidavit’s false material set to one side, the affidavit’s remaining content is insufficient to establish probable cause, the search warrant must be voided and the fruits of the search excluded to the same extent as if probable cause was lacking on the face of the affidavit.