Aggressive Maryland criminal defense attorneys know that the best way to attack a search warrant is by attacking the affidavit in support of the warrant. This is commonly referred to as a Franks Hearing.
In Franks v. Delaware, 438 U.S. 154, 98 S.Ct. 2674, 57 L.Ed.2d 667 (1978), the Supreme Court held that in certain defined circumstances a defendant can attack a facially sufficient affidavit. The Franks Court recognized a "presumption of validity with respect to the affidavit supporting the search warrant", and thus created a rule of "limited scope".
The rule created by the Franks decision requires that a dual showing be made before a court will hold an evidentiary hearing on the affidavit's integrity. This showing incorporates both a subjective and an objective threshold component. In order to obtain an evidentiary hearing on the affidavit's integrity, a defendant must first 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.
In addition to showing that the affidavit contains false information, a 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."