In 1984, the "Good Faith Exception" was added to the exclusionary rules allowing law enforcement officials who conduct lawful search and seizure on the basis of good faith, and later discover that a mistake was made in the issuance of the warrant that would violate the constitutional rights of the individual. Thus allowing the seized evidence to still be used in trial .A law enforcement official to be acting in good faith must be acting under an objective belief that what they are doing is constitutional and the facts would have to show that a reasonable officer could have made a mistake. If however there is an ulterior motive the exception does not apply.
United States v. Leon was the first case in which the "good faith exception" was accepted into constitutional law. Acting on the information from an informant Burbank, CA police department launched an investigation in drug-trafficking. With observations of the respondents Officer Rombach prepared an application for warrant to search three residences and automobiles for an extensive list of items. The search warrant was reviewed and issued to the officer. The ensuing search produced large quantities of drugs. Mr. Leon was then indicted on federal drug charges. Mr. Leon then proceeded to file motions to suppress the evidence seized pursuant to the warrant. It was found that the affidavit was insufficient to establish probable cause. Officer Rombach however had acted in good faith, the court rejected the suggestion of adding good faith exception do to reliance on a search warrant to the exclusionary rule. In this case the only question presented was the question whether a good-faith exception to the exclusionary rule should be recognized. The Supreme court held that the Fourth Amendment exclusionary rule should not prevent an officer from using the evidence found in a case where the officer was using reasonable reliance on a search warrant that was issued by a neutral magistrate even though it found to be invalid.