Massachusetts v. Sheppard

Massachusetts v. Sheppard involved the application of the good faith exception to the exclusionary rule, articulated in United States v. Leon on the same day that Massachusetts v. Sheppard was decided. In Massachusetts v. Sheppard, the Supreme Court held that although a warrant was found invalid after a search, the exclusionary rule did not apply. In United States v. Leon, the Court redefined the test for applying the exclusionary rule and narrowed the scope of Fourth Amendment protection for defendants. In Leon, the Court allowed evidence obtained in a search with a mistakenly issued warrant to be admitted because the police were acting in good faith. To determine whether the exclusionary rule should be applied, the Court used a cost-benefit analysis. The benefits of deterring police misconduct were weighed against the costs of suppressing the evidence. The purpose of the rule is to prevent the police from overstepping constitutional bounds. In Leon, the police did not overstep their bounds, so the Court concluded that there would be little benefit in applying the rule. Releasing a law breaker was a cost outweighing any benefit from attempting to prevent outrageous police behavior.

Decisions prior to Leon and Massachusetts v. Sheppard failed to create a good faith exception to the exclusionary rule. The Court finally created the good faith exception with Leon and applied it immediately in Massachusetts v. Sheppard, pointing out the possibilities of excluded evidence still being used in court, then noting the purposes of the exclusionary rule.

The Supreme Court revisited the good faith exception to the exclusionary rule in Arizona v. Evans (1995). A court employee mistakenly identified Isaac Evans as the subject of an arrest warrant. When a police officer stopped Evans for a traffic violation and searched him, using the incorrect warrant information, he found marijuana. The Supreme Court ruled that evidence seized in violation of the Fourth Amendment because of a clerk's error does not have to be excluded from the defendant's trial. The Court once again emphasized that the Fourth Amendment's purpose is to prevent unreasonable searches and seizures by the police.