Exclusionary Rule

Is the exclusionary rule justifiable? To put this question in context we must qualify the question by adding another: "Compared to what?" Defenders of the exclusionary rule rely heavily on the inadequacy of other remedies. If the constitution requires some effective remedy for violations, and if tort and administrative remedies have proved inadequate in practice, there is a strong case for requiring exclusion.

Critics have made a variety of objections to the rule. They argue that:

1. exclusion is costly inasmuch as it requires freeing guilty offenders;
2. that the rule does nothing for innocent victims of police misconduct, who have no evidence of crime to be suppressed;
3. that the rule's deterrent benefits are, as an empirical matter, doubtful;
4. that, if the rule does deter, it may overdeter by causing the police not to engage in searches that, although close to the line of illegality, are not over that line;
5. that the tort remedy might be made more effective by plausible reforms;
6. that exclusion causes police perjury, tolerance of police perjury by judges, and narrow interpretations of substantive Fourth Amendment rights by judges reluctant to free the guilty.

With respect to the cost associated with freeing the guilty, defenders of exclusion reply that any effective remedy for Fourth Amendment violations would result in the escape of guilty criminals. If the tort remedy, for example, were made a credible deterrent, fear of tort liability would cause the police to refrain from illegal searches. Since some illegal searches would reveal evidence of crime, alternative remedies would have the same costs as the exclusionary rule, in precise proportion to their effectiveness in deterring police misconduct.

In some cases, however, exclusion does cost the public a conviction that might have been obtained without violating the Constitution. If the police, having probable cause, decline to seek a warrant when one would have been issued, the suppression of the evidence prevents the police from obtaining it lawfully. A large majority of reported offenses, however, are never cleared by the police, so that it seems fair to assume that absent the illegality the police would not have come by the evidence lawfully. Drug cases, which involve offenses that would not be reported by a complaining witness, are even less likely to have been made lawfully. In those cases in which the prosecution can prove that the police would have obtained the evidence lawfully absent the illegality, the inevitable discovery exception allows the admission of the evidence. On the whole it seems fair to say that although the exclusionary rule may abort a few prosecutions the Constitution permits, the "cost" of freeing guilty criminals is for the most part attributable to the substantive constitutional rights that limit police power to search for evidence, rather than to the remedy used to deter future violations of those limits.

Indeed, an effective tort remedy might well overdeter the police, in the sense that officers fearful of personal liability might pass by lawful but borderline searches that might lead to the conviction of the guilty. Imposing tort liability on the police department or the municipality would create similar incentives on the part of police supervisors, who might train their officers to act conservatively out of fear of liability.

Defenders of the exclusionary rule admit that the rule does not provide any direct relief for innocent victims of police misconduct. Proponents of exclusion point out that if the rule deters, it will protect innocent citizens in future cases, although police motivated by sadism or racism rather than the desire to secure convictions will be unimpressed by the threat of exclusion. Because any effective deterrent will benefit guilty and innocent alike in future cases, tort remedies have an advantage over exclusion only to the extent that they compensate innocent victims, which exclusion clearly fails to accomplish. But so long as the tort remedies are ineffective, they fail to compensate the great majority of innocent search victims.

With respect to the empirical issue of the rule's deterrent effect on police behavior, proponents of the rule point to the following evidence. First, all modern studies find that the suppression of evidence is quite rare, involving perhaps 1 percent of felony cases (and in many of these cases the defendant may still be convicted on the force of untainted evidence). If evidence is only rarely suppressed, the argument goes, the police must be complying with constitutional standards. If, however, the rate of suppression is low because of successful police perjury or trial court hostility to freeing the guilty, there is no inconsistency between a low suppression rate and a low compliance rate.

Exclusionary rule proponents also point to the dramatic increase in warrant use that followed Mapp v. Ohio in those states whose courts had not adopted the exclusionary rule on their own. The increase is hard to explain except as deterrence in operation, because while other factors might have spurred the police to increase the frequency of searches, there was no practical reason for them to obtain search warrants except for the Supreme Court's decision in Mapp. Exclusionary rule proponents also point out that the police now devote considerable time to training officers in constitutional standards, to educating the force about new judicial developments, and to developing tactics that work around constitutional rules announced by the courts. Each of these phenomena is consistent with the hypothesis that the exclusionary rule deters. On the whole it seems fair to say that the exclusionary rule does influence police behavior, but that the extent of that influence is open to reasonable dispute.

Indeed, some commentators have taken the position that the exclusionary rule overdeters, reasoning that because the social cost of illegal searches is modest (the criminal's interest in escaping just punishment is not, on this view, a cost at all), and the loss of good cases is a substantial penalty on the police, that the police will be discouraged from aggressive action. If, however, it is true that the cost of lost convictions is attributable to the Fourth Amendment itself, not to the exclusionary remedy, the imbalance between the social costs and benefits of illegal searches disappears. Optimal deterrence comes from setting the sanction equal to the wrongdoer's expected gain discounted by the probability of escaping the sanction. Because the primary motive for illegal searches is successful prosecution, the rule comes close to setting the sanction equal to the government's anticipated gain. Indeed, from a strictly economic point of view, the rule may underdeter, because even when tainted evidence is suppressed the police still succeed in taking contraband off the street and acquiring information about criminal operations. Police therefore sometimes retain an incentive to search illegally even if they are certain that the fruits will be excluded.

Critics of the exclusionary rule usually admit that existing tort remedies are ineffective. They have proposed various reforms to make the tort remedy a more formidable deterrent. Among the more common suggestions are imposing liability on police departments and municipalities, assessing liquidated or punitive damages, and curtailing or abolishing good-faith immunity defenses. Whether reforms such as these could convert the tort remedy into an effective deterrent is a debated, but probably purely academic, point. Neither courts nor legislatures have embraced the reform proposals, even though they have appeared from prominent quarters in a steady stream for more than fifty years.

There are two major reasons for this failure. First, as a political matter, making it easier to sue the police at the expense of the taxpayer is not an attractive proposition to typical legislators. The beneficiaries of such a proposal are the likely targets of police excess, that is, young men, disproportionately black. The potential losers are those who might be protected from predatory crime by police disregard of constitutional standards. The latter group is more numerous and more influential than the former.

Second, on the merits, there is the standing risk that a tort remedy might set the sanction for Fourth Amendment violations higher than the social costs attending the violation, and thus inhibit justifiable as well as unjustifiable police actions. There is some evidence that officials exaggerate their exposure to liability. The police themselves seem to prefer exclusion to personal liability.

Evaluating the damages for Fourth Amendment violations is quite difficult. Should the victim of an arrest without probable cause recover the value of the lost time (say, thirty dollars an hour for the ten hours between arrest and release?) or ten thousand dollars for the arbitrary and degrading deprivation of personal liberty? Should the homeowner subjected to a warrantless search be awarded the price of new hinges and one visit from a cleaning service, or ten thousand dollars or more for invasion of privacy?

Even if broad agreement existed on the compensatory aspect of tort damages, the deterrent aspect poses further problems. What amount suffices to deter future illegal, but not future legal, arrests and searches? Set too high and damages would discourage legitimate police work; set too low and they would put constitutional rights up for sale at bargain prices. One advantage of the exclusionary rule is that it sets the sanction roughly equal to the government's expected gain, thereby approximating the sanction suggested by optimal deterrence theory.

The question whether alternative remedies might be made effective largely subsumes another issue sometimes raised about the exclusionary rule. Prior to Mapp v. Ohio relatively little substantive Fourth Amendment law was established, because many jurisdictions had no exclusionary rule and because few tort suits were brought. Since Mapp the Supreme Court alone has decided dozens if not hundreds of Fourth Amendment cases. While uncertainties and confusion still surround some issues, the law has become better defined as a result.

Some defenders of the exclusionary rule point out that without the rule, there would be no procedural vehicle for establishing or changing the substantive law. This is a strong point against simple abolition of the rule. But if an effective tort remedy replaced the exclusionary rule, and if damages were generous enough to encourage suits, the tort system would provide a new procedural forum for shaping substantive Fourth Amendment law.

There is growing recognition that some police officers will commit perjury to avoid the suppression of evidence. The extent of the phenomenon is necessarily conjectural. If the reason why suppression motions rarely succeed is that the police violate the applicable rules and then successfully lie about it later, the exclusionary rule would not have accomplished very much.

Widespread perjury is by no means inconsistent with widespread compliance. Proponents of the rule believe that the training programs and changes in police culture fostered by Mapp reduce the occasions in which the police violate the applicable law in the first instance, even if some officers are willing to lie on the stand after it becomes clear that the discovery of the evidence was illegal. Police testimony could be subjected to more searching scrutiny, by such measures as evidentiary presumptions against consent to search or the admissibility of polygraph evidence at suppression hearings. Finally, it is worth noting that tort remedies, which might expose police departments or individual officers to substantial financial liabilities, would be more likely to transfer police perjury from the criminal to the civil courts than to reduce its prevalence.