Nov 19, 2020

An exception to the exclusionary rule barring the use at trial of evidence obtained under an unlawful search and seizure (see the Fourth Amendment). If officers had reasonable, good faith belief that they were acting according to legal authority, such as by relying on a search warrant that is later found to have been legally defective, the illegally seized evidence is admissible under this rule. Evidence obtained by the use of a warrant later found to be unsupported by probable cause is admissible if the investigating officers acted in reasonable reliance that the warrant was valid.

Arizona v. Evans is an example of the good-faith exception in action: officers relied on a search warrant that turned out to be invalid. In Davis v. the U.S., the U.S. Supreme Court ruled that the exclusionary rule does not apply when the police search reliance on binding appellate precedent allowing the search. Under Illinois v. Krull, evidence may be admissible if the officers rely on a statute that is later invalidated. In Herring v. U.S., the Court found that the good-faith exception to the exclusionary rule applied when police employees erred in maintaining records in a warrant database.

The Fourth Amendment protection against unreasonable searches and seizures usually allows a defendant to exclude evidence from a trial if it was unconstitutionally seized. However, there are several exceptions to search and seizure rules. One of these involves evidence that law enforcement seized in good faith. If the police make a reasonable mistake in conducting a search, evidence of a crime that they find as a result may be admissible. The U.S. Supreme Court has ruled that a court can consider evidence obtained from a search that appeared to have a lawful basis, such as a search supported by a warrant. If the warrant later turns out to have been invalid, the police may not be held accountable for searching while relying on it.


The reason for a defendant’s right to suppress evidence obtained through an unconstitutional search is to prevent law enforcement from engaging in misconduct. Thus, when law enforcement takes reasonable steps, suppressing the resulting evidence does not serve the purpose of the Fourth Amendment. Debates have arisen over whether this reasoning is valid. Some legal scholars believe that criminal defendants should not pay the price for mistakes by the police, even if there were no bad intentions. It is also often hard to draw the line between innocent mistakes and mistakes that seem innocent but may be intended to dodge constitutional rules.