An Epistemic Defense of Exclusionary Rules in the Criminal Justice System
John R. Harris
Abstract: In criminal trials jurors are charged with determining if a crime occurred, and if so, did the defendant commit the crime. If we want jurors to get at the truth, then we should work to ensure that they have all the relevant and reliable information necessary to do so. It appears that exclusionary rules subvert the truth-seeking goal of the criminal justice system. Exclusionary rules prevent the jury from being presented with all the relevant information about the criminal case. In this paper I consider two powerful arguments against the use of exclusionary rules, and I argue that these arguments fail. Exclusionary rules can, and in some cases do, serve an important epistemic purpose.
Introduction
Evidence plays an important role in our lives. If we hope to rationally answer a question, then we will frequently, if not always, seek out evidence. When patients suffer from ailments doctors gather evidence in order to diagnose those ailments. In order to determine the best treatment for those illnesses doctors again rely on evidence gathered by themselves and others. Scientific questions are frequently answered in large part by gathering and interpreting evidence. As we all are well aware gathering and evaluating evidence plays an indispensible part in science, medicine, academia, and, of course, the criminal justice system.
There is no doubt that some evidentiary gathering and evaluative systems are better than others. Most of us have a great deal of confidence in the evidence gathered by scientists and we likely have little confidence in the practices of astrologists. What should interest us here is what differentiates good practices from bad. Perhaps more modestly, we should hope to identify some key practices with respect to evidence that will make it most likely that we will be lead to truth rather than error. Having good evidence will not guarantee that we arrive at correct conclusions, but our prospects will be grim without it.
When attempting to answer a question we should seek out evidence, but not everything counts as evidence. When gathering evidence to answer a question we do not begin to gather any and all data. If I want to know if I have beer in the refrigerator I would not begin by weighing my cats. To be sure, what my cats weigh is evidence of something, but this is not germane to the issue at hand. So, we do not focus our attention simply on evidence, but to be more precise we do—or should—focus our attention on relevant evidence. That is, we focus on that subset of available evidence that will help us answer the question at hand.
There is more to this story than just relevancy. Some evidence we may have available to us could be relevant, but if that evidence is not trustworthy or if we are uncertain of its trustworthiness, then we should we should give it less weight or ignore it entirely. If Jones claims to have witnessed a crime, then we will likely think that his testimony is relevant. Should it turn out however that Jones was impaired in some way at the time then we should also think that the evidence he provides is unreliable. This is simply a reminder that we want relevant and reliable evidence when seeking the truth.
Finally, we also want to consider all the relevant, reliable evidence that we can. If we consider only some small portion of the evidence, we may land on spurious conclusions. We may be drawn to certain conclusions when we have access to partial evidence that, when considered in light of all the evidence, seem less attractive than other conclusions. Thus, we want access to comprehensive evidence, or at least as comprehensive as we can hope for.
We need not assume this is all we want from our evidence, but relevant, reliable, and complete evidence certainly seems like a good beginning. If the evidence we rely on satisfied these conditions, then we are on the right track. With these features in mind, consider what role they play in criminal proceedings and how exclusionary rules may serve to undermine them.
Exclusionary rules serve to prohibit certain information from being presented in (typically) criminal trials. There are numerous exclusionary rules and they serve to exclude a wide variety of evidence. In Mapp v. Ohio the US Supreme Court extended the Fourth Amendment protection against illegal search and seizure to state courts (previously the Court has rules that the Fourth Amendment only applied to Federal Courts). Effectively states are now prohibited from introducing evidence that was gathered illegally by police. This is but one example of the sorts of evidence that can be excluded from trials. Other examples include hearsay, spousal privilege, recanted confessions, key witnesses pleading the Fifth, evidence that is considered unfairly prejudicial, and instructions that forbid jurors from taking the defendant’s silence into consideration when considering their guilt—to name only a few.
If, however, the central function of trials is epistemic, that is to discover the truth, then such exclusionary rules seem to be in conflict with that function. Exclusionary rules appear to prevent juries and judges from considering all the relevant information that may speak to the guilt or innocence of the defendant(s). This practice seems at odds with the best practices employed by other enterprises that take their key function to be epistemic. The scientific enterprise would be undermined, to say the least, if scientists ignored relevant information, were prevented from searching for further evidence, or prevented from asking questions of those who provide key evidence, yet this is exactly what happens to jurors.
Raising questions about the curious role of exclusionary rules is by no means a new phenomenon. Jeremy Bentham objected to many of these practices in his essay “Rationale of Judicial Evidence, Specifically applied to the English Practice,” but he has by no means been the last. More recently Larry Laudan and Susan Haack have called into question the epistemic role of exclusionary rules in the US legal system, and both worry that they do more harm, epistemically speaking, than good.[1]
Needless to say, there are other goals that trials serve than just epistemic, and one may be inclined to argue that these other goals, perhaps fairness or limits on the exercise of state power, may serve to offset the epistemic concerns that motivate Bentham, Laudan, and Haack’s concerns. But for our purposes we will set those aside for the time being, though I will return to these at the end of this essay, and instead focus solely on the epistemic case against exclusionary rules. It has often been asserted that the epistemic role of courts is their primary function. Justice Lewis Powell wrote:
Underlying the question of guilt or innocence is an objective truth: the defendant, in fact, did or did not commit the acts constituting the crime charged. From the time an accused is first suspected to the time the decision on guilt or innocence is made, our criminal justice system is designed to enable the trier of fact to discover the truth according to law.[2]
If our criminal justice system is, in fact, so designed, then preventing jurors or judges from considering all relevant information does seem curious. If exclusionary rules do prevent jurors from considering all the relevant information, then they do appear to undermine the core function of the criminal justice system.
In this paper I will consider the epistemic case against exclusionary rules. In what follows I will focus primarily on Larry Laudan’s argument against exclusionary rules. I do so because Laudan offers the most comprehensive and compelling case against exclusionary rules in his book Truth, Error, and the Criminal Law. Laudan does not necessarily believe that exclusionary rules are always truth thwarting, but he believes they are highly suspect.[3] Unless we can offer strong and empirically well-supported evidence in their favor we should eliminate exclusionary rules. As it happens Laudan is doubtful that such strong and well-supported evidence exists for the most part. In section 1 I consider the general argument against exclusionary rules. What we will find is that the crucial issue is whether exclusionary rules do subvert the epistemic role of the criminal justice system. In section 2 I consider one key line of argumentation in support this claim: exclusionary rules generally undermine the epistemic goals of the criminal justice system. In section 3 I consider the example of forbidding recanted confessions from being considered by the jury, and how this may subvert the epistemic goals of a trial. In section 4 I argue that the case against recanted confessions fails. That is, we can justify excluding recanted confessions on epistemic grounds. In section 5 I argue that the general epistemic case against exclusionary rules also fails. Exclusionary rules do not “exists under a strong cloud of illegitimacy.”[4] In fact, they can serve as an important role in preventing epistemically dubious information from misleading jurors. We can, contra-Laudan, find strong and empirically well-supported support for their use in many cases. Though, to be clear, my thesis here will not be the much stronger claim that all exclusionary rules, especially those found at work in the US legal system, are epistemically justified.
1. The Case Against Exclusionary Rules
To begin consider a basic argument against exclusionary rules:
P1. Truth is the primary goal of the criminal justice system
P2. If a practice or set of rules serves to interfere with or undermine the primary goal of an institution, then the goal should be altered or that practice or set of rules should be abolished.
P3. Exclusionary rules interfere with the primary goal of the criminal justice system.
P4. We should not alter the primary goal (the truth seeking imperative) of the legal system.
C. We should abolish exclusionary rules.
The argument is valid so we need to see if the premises are in fact true.
Consider the case for premise 1—that truth is the primary goal of the criminal justice system. As we have already seen Justice Powell was inclined to see the law as such, and this by no means was the only time that courts have asserted the importance of the truth-seeking imperative. However, we need not rely merely on declarations from jurists to support his point. There is a moral argument that supports premise 1. Given the profound harms that attach to criminal convictions we must do everything we can to insure that the outcome of criminal proceedings is correct. Perhaps we are inclined to think that justice is an equally important value that the judiciary should be pursuing in conjunction with truth. This may be, but no doubt we want to be certain that when we punish someone she is in fact guilty of the crime for which she has been convicted, and when we set someone free she is in fact innocent. We can see the paramount importance of truth even in matters of justice if we consider cases where he judiciary gets the wrong outcome. It is no doubt a profound injustice when we discover that an innocent person has been convicted and served a lengthy sentence for a crime she did not commit. Of course, it is also a serious injustice when the guilty are set free. By insisting that truth remain a central goal of the judicial system we work to avoid injustices like these. No gains in justice can offset the serious harms associated with such errors of fact. This is not to suggest there is nothing controversial about premise 1, but for the time being I believe we can see why one should find premise 1 to be, at least, initially plausible.
The case for premise 2 is fairly straightforward. If there are practices in place within an institution that undermine that institution’s primary purpose, then we must either act to revise those practices or should we feel particularly strong about those practices, then we should change the institution’s primary purpose to reflect that. So, suppose a group takes the primary purpose of heir religion that they go out and save lost souls by conversion to their religion. If this religious group also forbids proselytizing, then something here must give. They must decide if they are truly committed to converting the unsaved, and if so, they must abandon their prohibition on proselytizing. Alternatively, if upon reflection they find that the prohibition on proselytizing is more central to their fundamental values, then they must alter the primary purpose of their religion. At heart here we find simply a matter of consistency.
Consider how this applies to the present context. If it is true that exclusionary rules are at odds with the epistemic function of the legal system, then we find—given premise 2—that we must either abandon the epistemic imperative or we must get rid of exclusionary rules. Given what we have already said in defense of premise 1 it seems incredibly difficult to give up the epistemic imperative. What would it mean to abandon the truth-seeking imperative of the criminal justice system? Would we be prepared to accept false convictions now? It is something of truism within the legal system that it is better to let one hundred guilty men go free than to let one innocent man go to jail. If we abandon our commitment to the truth will we also accept that innocent people must go to prison? All of this simply serves to corrupt a legal system. It seems best then, that if we are faced with a choice between keeping exclusionary rules and rejecting the epistemic imperative or keeping the epistemic imperative and rejecting exclusionary rules, the latter is the best option available to us. Premise 4 seems to stand on solid ground.
But should we think that exclusionary rules interfere with the epistemic function of the criminal justice system? Premise 3 is the most contentious of the premises, and thus deserves more careful discussion than what has been said in defense of the argument to this point. In the following two sections I consider two different lines of support for premise 3.
2. The General Epistemic Case Against Exclusionary Rules
Ideally in a criminal case jurors will be presented with will reliable, relevant, and comprehensive information necessary to make the decision. Efficiency demands that this process be streamlined to some extent. The analogy between a jury and a scientific inquiry is inexact. Ideally, in a scientific inquiry, there will be no time limit in which the scientists must operate. They will be free to consider all relevant alternative explanations for a given phenomenon, they can run tests to determine if those alternatives offer a more plausible explanation. Not so with criminal trials. Jurors’ purposes are more narrowly focused. They are not charged with determining if a crime happened and if so, who did it. Rather, they are asked to determine if a crime happened and if so, is there sufficient evidence to conclude that the defendant did it. In effect they are not asked to determine who really committed the crime. We could imagine cases in which there is strong evidence that Smith committed a crime. Suppose that the evidence is strong enough that it satisfied the requirement that the defendant is guilty beyond a reasonable doubt, and the jury, as a result, convicts the defendant. All of this is consistent with the fact that there is other even stronger evidence that suggests that it was not Smith but Jones who committed the crime. If jurors did not consider the evidence in favor of Jones’s guilt rather than Smith, they have done nothing wrong. Their job is to evaluate the evidence in favor of Smith’s guilt, not Jones’s. If a scientific inquiry were conducted in the same way we would think it had failed. We may think prosecutors and the police have failed in some way by not pressing the case against Jones, but that is beside the point. What we need to see here is that there are some significant ways in which the job of the juror is different from the job of the scientist.
Still, if we hope that such cases are anomalous, then we will want insure that jurors have access to all the reliable and relevant information. Even in this respect the juror’s task is different from the scientists. Consider how determinations of relevance are made in criminal justice cases. Whereas members of the scientific community are left to decide what information is relevant, this is not the case with jurors. Instead it is left up to the judge presiding over the case to determine if evidence is relevant. Laudan argues that here a judge should consider if the evidence were credible would it result in a change in probability that the crime occurred or that the defendant committed the crime. If so, then the evidence should be presented to the jury.[5] Of course, there may be cases in which IF some evidence were credible it would change the probability of the hypotheses that a crime occurred or that the defendant committed it, but we still think it should not be considered. So more must be said about this. Laudan clarifies the idea at play here when he writes, “Any testimony or physical evidence that would make a reasonable person either more inclined or less inclined to accept these hypothesis is relevant. Everything else is irrelevant.”[6] Suppose the prosecution wants to introduce evidence that the shape of the defendant’s skull is such that she has a high propensity to commit the type of crime that she is accused of committing. Of course, phrenology is pseudoscience and thus should not be considered. Rather, the hypothetical should be limited to what would lead a reasonable juror to alter her probabilities, and phrenology should not lead a reasonable juror to alter her probabilities. It is thus, in that respect, irrelevant.