The Leon Good Faith Exception
In United States v. Leon, 468 U.S. 897 (1984), the Supreme Court identified four situations in which the good faith exception to the exclusionary rule would not apply.
First, evidence should be suppressed if the issuing magistrate was misled by an affidavit containing false information or information that the affiant would have known was false but for the affiant's reckless disregard for the truth.
Second, the exception will not apply when the issuing magistrate wholly abandons the judicial role. Third, the good-faith exception will not apply when the affidavit in support of the warrant is so lacking in indicia of probable cause as to render official belief in its existence entirely unreasonable.
Thus, the exception does not extend to situations in which the officer obtains a warrant based on a "bare bones" affidavit and then relies on good faith execution by innocent colleagues in order to sustain the warrant. Leon, 468 U.S. at 923 n24, 104 S. Ct. at 3420 n24.
Fourth, the exception will not apply when a warrant is so facially deficient that the executing officer could not reasonably believe it was valid.
The Leon rule will not exclude evidence, however, when an officer's reliance on a technically sufficient warrant is objectively reasonable. Id. at 922, 104 S. Ct. at 3420.