When Does the Exclusionary Rule Apply?

The exclusionary rule has lasted more than a century in federal court and more than half a century in the courts of the states. Time has not dulled the controversy created by the rule. Although recent Supreme Court opinions devote relatively little time to debating the constitutional underpinnings of the rule, the Justices continue to argue over the rule’s utility. In particular, twenty-first century exclusionary rule cases have contested the costs (measured in the loss of relevant, reliable evidence) and benefits (measured in deterrence of official misconduct, particularly the kind that violates constitutional rights). Recent cases have narrowed the scope of the rule—applying it to less misconduct than was covered in the decades after Mapp v. Ohio—but have not abolished it. Defendants retain powerful incentives to seek the exclusion of evidence, especially in cases of brazen police misconduct and when there are clear violations of well-established rights.

In our next case, the Court considered whether violations of the knock-and-announce rule—covered in Chapter 7—justify the exclusion of evidence found during a police search.