Mapp v. Ohio

The Court had long been looking for an opportunity to overturn Wolf. Just a year earlier, in Elkins v. United States (1960), the Court had found that the Due Process Clause of the Fourteenth Amendment afforded criminal suspects protections against unlawful searches and seizures at the state level that were equivalent to those that the Fourth Amendment made binding on the federal government. But because Elkins did not involve a state criminal prosecution, the Court could not use it as an opportunity to revisit Wolf. Now, with Mapp, the Supreme Court seized the opportunity to do so.

Writing for the Court, Justice Clark found ample reason to apply the exclusionary rule at the state level. Noting that without it the Fourth Amendment prohibition on unreasonable search and seizure becomes merely "a form of words." In Elkins he went on to elaborate on the practical reasons for implementing the exclusionary rule across the board:

There are those who say . . . that under our constitutional exclusionary doctrine `[t]he criminal is to go free because the constable has blundered.' . . . The criminal goes free if he must, but it is the law that sets him free. Nothing can destroy a government more quickly than its failure to observe its own laws, or worse, its disregard of the character of its own existence . . . Nor can it lightly be assumed that, as a practical matter, adoption of the exclusionary rule fetters law enforcement. Only last year this Court expressly considered that contention and found that `pragmatic evidence of a sort' to the contrary was not wanting.

Stewart, who wrote the majority opinion in Elkins now refused to join the Court's opinion. Although he voted with the majority to reverse Dollree Mapp's conviction, he wrote his own opinion laying out his rationale for doing so. Because Mapp's lawyers had not, in his view, properly addressed the issue of overturning Wolf in their legal papers or in their oral argument before the Court, the Court had no business using this opportunity to do so of its own volition.

In the end, the opinion of the Court expressed only a four-vote plurality that favored overturning Wolf. Justice Black turned out to be the swing vote. Although he joined the Court's opinion, he did so for his own reasons. Black was perhaps the most ardent supporter of the incorporation doctrine, making most of the guarantees of the Bill of Rights applicable to the states via the Fourteenth Amendment. Now, however, he found that it was a combination of the Fourth and Fifth Amendments--rather than the Fourteenth Amendment--that required state courts to honor the exclusionary rule. He wrote a separate concurring opinion that was not joined by any other justice.

The three dissenters, Harlan, Frankfurter, and Whittaker--all of whom had dissented in Elkins--continued to disapprove of the incorporation doctrine. Following that logic, they refused to apply the exclusionary rule to the states.

Despite the confused pattern of voting and opinions in Mapp, it soon became the law of the land--and remains so. State police and state courts continue to be required to observe Fourth Amendment guidelines when gathering and assessing evidence in criminal matters.