Franks Hearing is a hearing to determine whether a police officer's affidavit used to obtain a search warrant that yields incriminating evidence was based on false statements by the police officer. The name is derived from the case Franks v. Delaware, 438 U.S. 154 (U.S. 1978), which affirmed the right of defendants to challenge a warrant seizing their person, papers or effects and otherwise outlining the case against them. In this case the Supreme Court held that in certain defined circumstances a defendant can attack a facially sufficient affidavit. In order to obtain an evidentiary hearing on the affidavit's integrity, the following must be shown:
- First, the defendant must make a substantial preliminary showing that a false statement knowingly and intentionally, or with reckless disregard for the truth, was included by the affiant in the warrant affidavit. This showing must be more than conclusory and must be accompanied by a detailed offer of proof.
- Second, defendant must show that the false information is essential to the probable cause determination. That is, if a court finds that when material that is the subject of the alleged falsity or reckless disregard is set to one side, there remains sufficient content in the warrant affidavit to support a finding of probable cause, no hearing is required.
Upon making this two-part preliminary showing a defendant is entitled to a hearing. At this hearing, the defendant has the burden of proving the allegations by a preponderance of the evidence. If an affiant's material perjury or recklessness is established by a preponderance of the evidence, the warrant must be voided and evidence or testimony gathered pursuant to it must be excluded.