Police pay more attention to the Fourth Amendment than they did after the Mapp decision.
However, many officers don’t take the rule into account when they’re deciding whether to
make a search or seizure.
The social costs of letting guilty criminals go free by excluding credible evidence that would
convict them might not be as high as we commonly believe. Prosecutors almost never reject
cases involving violent crimes because of the exclusionary rule. In California, evidence
seized illegally has led to dismissals in a mere 0.8 percent of all criminal cases and only 4.8
percent of felonies.
The exclusionary rule affects only a small portion of cases, and most of those aren’t crimes
against persons. Less than one-tenth of one percent of all criminal cases will be dismissed
because the police seized evidence illegally.
Prosecutors and police don’t believe that Fourth Amendment rights or their protection via the
exclusionary rule are a significant impediment to crime control.
Many police officials report that the demands of the exclusionary rule and the resulting police
training on Fourth Amendment requirements have promoted professionalism in police
departments.
The exclusionary rule appears to be providing a significant safeguard of Fourth Amendment
protections for individuals at a modest cost, in terms of either crime control or effective
prosecution.