Exclusionary Rule

The history of the rule reflects this ambivalence. The common law did not allow the exclusion of evidence on account of irregularities in the way in which a party acquired it. Instead, a citizen wronged by an illegal search could sue the wrongdoers for the tort of trespass. Anyone who invaded another's property was guilty of trespass and had to pay damages, unless the intruder had some positive legal authority such as a valid warrant. The framers of the Fourth Amendment included the warrant clause to prevent the new government from cutting off the trespass remedy by issuing general warrants—one of the abuses that had incited the revolution.

A decline in the efficacy of the tort remedy coincided with the development of modern police forces in the mid–nineteenth century. Typically the police did not (and do not) target the rich and powerful for intrusive investigations. The generally poor, generally uneducated, and often minority-race victims of illegal searches were in a poor position to recruit lawyers to bring suits; they certainly could not count on generous jury verdicts against the police.

The Supreme Court recognized the exclusionary rule early in the twentieth century. Although the Fourth Amendment exclusionary rule may have arisen from the then-prevailing view that the Fifth Amendment privilege against self-incrimination shielded individuals from having their own property used against them as evidence, the early cases soon recognized a Fourth Amendment right to suppress illegally seized evidence even when the party invoking the rule had no Fifth Amendment rights (i.e., a corporation) and even when the evidence to be suppressed was illegal to possess at all.

The early cases, however, were limited to federal prosecutions. Criminal law enforcement in the United States is primarily the responsibility of state, rather than federal, officers. Some state courts followed the Supreme Court's lead and adopted the exclusionary rule; others adhered to the common law rule admitting evidence without regard to how it was obtained. Two of the past century's most celebrated American jurists wrote opposing opinions on the issue during this period. A good way to begin thinking about the exclusionary rule is to compare Judge Benjamin Cardozo's opinion for the New York Court of Appeals in People v. Defore, 150 N.E. 585 (N.Y. 1926), refusing to adopt the exclusionary rule, with Justice Roger Traynor's opinion for the Supreme Court of California in People v. Cahan, 282 P.2d 905 (Cal. 1955), adopting the exclusionary rule.

Not until 1961, in the watershed case of Mapp v. Ohio, 367 U.S. 643 (1961), did the Supreme Court hold that the exclusionary rule applies to the states as a matter of Fourteenth Amendment due process. In states that had not followed the exclusionary rule on their own prior to Mapp, the Mapp decision had a dramatic impact. Warrant use in major cities went from a handful to hundreds per year; search-and-seizure law became the subject of police training programs. These developments would not have occurred if the tort remedy had been an effective deterrent. Had the tort remedy been effective, the police in states without the exclusionary rule would have been using warrants and training their officers in constitutional law all along.

Even the liberal Warren Court, however, was reluctant to free the guilty. As soon as the rule applied to the states, where crimes of violence are typically prosecuted and where the great majority of prosecutions for all types of offenses are brought, the Court began to adopt narrower interpretations of substantive Fourth Amendment rights, and to recognize exceptions to the exclusionary remedy. For example, shortly after Mapp the Court excluded undercover operations from any scrutiny whatsoever under the Fourth Amendment; refused to apply Mapp to free prisoners previously convicted by illegally obtained evidence; and reaffirmed the rule that only the search victim can invoke the rule, even when the evidence incriminates others.

As the Court grew more conservative during the 1970s (as it has remained ever since), the exceptions to the exclusionary rule have threatened to swallow the rule. Illegally obtained evidence is now admissible in the following situations:

1. in the government's case at trial against any person whose rights were not violated by the illegal search;
2. in the government's case at trial if the officers who committed the illegal search were acting in reasonable, good-faith reliance on a warrant, a statute, or a court record later determined to be unconstitutional or erroneous;
3. in the government's case at trial, if the government can prove that the evidence would have been discovered inevitably in the absence of the illegality;
4. in the government's case at trial, if the illegal police conduct led to the evidence only by an attenuated chain of events;
5. to impeach the defendant's testimony, if he chooses to take the stand at trial;
6. in preliminary and collateral proceedings, such as before the grand jury.

In deciding these cases the Court has regarded deterring future police misconduct as the sole reason for the rule. When weighing the desirability of an exception, the Court has explicitly balanced the likely deterrent benefits against the apparent costs of freeing the guilty. Although this approach has usually favored the prosecution, the Court has at least once found that the balancing test requires a narrower, rather than a broader, interpretation of the exceptions. In that case, the Court held that the impeachment exception did not allow the use of tainted evidence to contradict the testimony of a third-party witness for the defense, as distinct from the testimony of the defendant himself.

In the main, however, the balance has clearly inclined in favor of the government. One dramatic illustration is the good-faith exception recognized for searches conducted pursuant to facially-valid warrants recognized in United States v. Leon, 468 U.S. 897 (1984). Because the police enjoy good-faith immunity from tort suits, withholding the exclusionary rule leaves no apparent remedy when the police obtain a warrant without showing probable cause. The Fourth Amendment flatly declares that "no warrants shall issue, but upon probable cause." The good-faith exception means that when warrants do issue without probable cause, neither exclusion of the fruits, nor civil liability, follows from the violation.

As the Court has come to focus exclusively on deterrence in applying the rule, some legal scholars have argued that illegally obtained evidence should be suppressed without regard to deterrence. It is claimed, for instance, that excluding tainted evidence is necessary to preserve judicial integrity, or to vindicate the principle of judicial review. The challenge confronting all such nondeterrent theories of exclusion is to connect the search for, and the use of, the evidence, even when the courts impose a sanction adequate to deter future violations.

This connection is not immediately apparent. Suppose the police discover narcotics at the home of A pursuant to a valid warrant, and an identical lot of drugs in the home of B but without a warrant. There does not seem to be any normative distinction in favor of B. We do not want the police in future cases to search without warrants, so we might exclude the evidence against B to prevent searches of completely innocent persons in other cases. But we would not say that B has a personal right to exclusion divorced from future consequences.

Suppose instead that the police, without a warrant, search the home of C and discover nothing incriminating. If exclusion were thought of as a personal right, the innocent C would have less protection against unreasonable searches than the guilty B. The Fourth Amendment is not generally regarded as conferring substantive immunity for crimes committed in private. So long as that judgment stands, connecting the search and the use of the evidence will be difficult. Given that innocent search victims possessed no evidence a court could later exclude, exclusion would not seem to be an indispensable remedy. What is indispensable is some effective deterrent against future violations. The Supreme Court has been willing to require the exclusionary rule until such time as Congress or the states establish an effective alternative.

A jurisdiction that adopted and enforced an effective alternative deterrent to police misconduct would have a strong case for abolishing the exclusionary rule. If, for instance, police who engaged in illegal searches were suspended for a year without pay for the first infraction, and terminated for a second, and if this policy were monitored and enforced effectively, there would be few illegal searches and no need for the further deterrent of the exclusionary rule. Note, however, that under such a system, the public would lose the same evidence as the exclusionary rule suppresses, because it would never be discovered in the first place. Note also that under such a regime the exclusionary rule would not be particularly unpopular because it would only rarely come into play, as the administrative disciplinary system would prevent most illegal searches from ever taking place. Perhaps because of these considerations, no jurisdiction in the United States has adopted strict administrative, tort, or criminal sanctions for illegal searches.

Even if deterrence is the key to the rule, it hardly follows that the Court has assessed the costs and benefits of exclusion correctly. For example, preventing persons other than the search victim to invoke the exclusionary rule goes a long way toward undermining the rule's deterrent threat. In some cases the police deliberately target third-party custodians of evidence for illegal searches, knowing that the target of the investigation will not be allowed to challenge the legality of the search. More commonly, law enforcement agents investigating a conspiracy know that many of the conspirators will not have standing to challenge the search or arrest of one of their number. The standing exception seems more like a convenient way to escape the substantive limits of the Fourth Amendment than a reasoned exposition of a deterrent theory of the exclusionary rule.

Moreover, each exception to the exclusionary rule recognized by the Court reduces the sanction imposed on the government for illegal searches and seizures. Standing alone, the impeachment exception or the inevitable discovery exception might do little damage to deterrence. Given all the exceptions together, however, the disincentive to conduct illegal searches has been significantly reduced.

Despite the various exceptions, the exclusionary rule lives on, thirty years after Warren Burger replaced Earl Warren as Chief Justice. Even conservative justices have been unwilling to abolish the rule, just as even liberal judges recognized some exceptions. The exceptions reflect the reluctance to release patently guilty offenders; the persistence of the rule reflects the reluctance to provide no effective remedy for violations of the Constitution.