Legal systems, and especially common-law legal systems, claim to place special weight in their decision-making on the constraints of precedent. In law, more than elsewhere, legal decision-makers are expected to follow previous decisions just because of the very existence of those decisions, and thus without regard to the current decision-maker’s agreement with or persuasion by the content of those previous decisions. It is the very “pastness” of previous decisions, and not necessarily the current decision-maker’s view of the correctness of those previous decisions, that gives the previous decisions their authority. Why this is so, and, more importantly, what it means for it to be so, is the principal topic of this chapter.
It is worth noting at the outset that precedent, although arguably concentrated in, and more important in, law than in other decision-making domains, and more important in, common-law legal systems than in their civil-law counterparts, is by no means unique to legal decision-making. Younger children who demand to be treated just as their older siblings were treated at the same age are relying on arguments from precedent, as are consumers who insist on being given the same prices and terms as those offered to prior customers, as are members of committees and other collective decisionmaking bodies who treat the very existence of a previous committee decision on some subject as providing a reason to make the same decision on some subsequent occasion.
But although arguments from precedent, as well as the correlative arguments against a proposed course of action for fear of creating a dangerous precedent, appear at times to be ubiquitous, such arguments are alleged to have greater weight in the law, and to be more pervasive in the law as well. Whether these comparative claims of frequency and weight are in fact true is an interesting and important empirical question, but in this chapter I nevertheless assume the truth of the conventional wisdom that a norm of precedent is, descriptively, a more central feature of legal decision-making than it is of decision-making, even good decision-making, generally. Thus, although the analysis presented in this chapter may have some application to any domain in which arguments from precedent have some purchase, it will still be focused almost entirely on the law.
Precedent: The Basic Idea
Precedent is centrally about the (not necessarily conclusive) obligation of a decisionmaker to make the same decision that has been made on a previous occasion about the same or similar matters. That seems straightforward enough, but it is nevertheless important to distinguish two different dimensions of precedent. One, which we can label vertical precedent, describes the obligation of a court to follow the decision made by a court above it in the judicial hierarchy on the same question, even if that question has arisen in a different case (Schauer 2009: 36–37). When trial courts make decisions on questions of law (as opposed to determining the facts in the particular matter before them), they are expected to follow—toobey—the decisions of the appellate courts that sit above them in what can be analogized to the military chain of command, just as the first-stage appellate courts must, in turn, follow the decisions made by courts abovethem. So, in the American federal courts, for example, federal district courts are obliged to follow the decisions of the court of appeals in their circuit, and the courts of appeals are similarly obliged to follow the decisions of the Supreme Court of the United States.
To be contrasted with this sense of vertical precedent is horizontal precedent, conventionally referred to as stare decisis (typically translated as “stand by what has been decided”) (Lee 1999; Wise 1975). Understood horizontally, the obligation of a court is not the obligation to obey a decision from above, but is instead the obligation to follow a decision by the same court (although not necessarily by the same judges) on a previous occasion. And thus the obligation is, by definition, not one of obeying an institution higher in some hierarchy. Rather, the obligation to follow precedent in its horizontal dimension is, in essence, about treating a prior decision as if it came from above, even if it did not, and is accordingly about following an earlier decision solely because it came earlier. Horizontal precedent is about treating temporal priority as sufficient grounds for authoritativeness in its own right.
Thus, both vertical and horizontal precedent are about the authoritative character possessed by, or to be given to, prior decisions. And therefore the authority of a precedent is, as with authority in general, content-independent (Hart 1982). It is the source or status of a precedent that gives it its authority—that provides the reason for a decision—rather than the content of the precedent or the content or persuasiveness of the reasoning it incorporates. For just this reason, the force of precedent is most apparent when the decision-maker in the present case—the instant case—disagrees with the result reached in the previous case—the precedent case (Schauer 1987). When the decisionmaker in the instant case agrees with or is persuaded by the outcome or the reasoning in the precedent case, then an argument from precedent is superfluous. It is only when the decision-maker in the instant case disagrees with the outcome or the reasoning in the precedent case that the content-independent authority of a precedent becomes apparent (Alexander 1989). In such instances, it is most obvious that the decision-maker is under an obligation to follow the precedent because of its source or status, and just because of that source or status, even if the decision-maker in the instant case believes that the decision in the precedent case was mistaken.
Although the force of a norm of precedent is thus most apparent when it compels a decision-maker to do what she would not otherwise have done, it is still important to note that the content-independent reasons supplied by a precedent need not be conclusive. A decision-maker in the instant case who accepts the obligations of precedent, and thus accepts that precedents supply content-independent reasons for decisions, may nevertheless believe that other reasons—legal, moral or prudential, for example—may outweigh the reasons supplied by the content-independent status of the precedent. So although the Supreme Court of the United States professes (whether the court actually behaves in such a way is less certain, as will be discussed in a subsequent section) to operate under a rule of stare decisis, such that it believes itself under an obligation to follow its own previous decisions even when a majority of the current court thinks those decisions mistaken, the existence and even the internalization of such a rule is not inconsistent with the current—instant—court, on occasion, overruling or refusing to follow one of its earlier decisions. When, famously, the Supreme Court in Brown v. Board of Education ((1954) 347 U.S. 483) in 1954 overruled Plessy v. Ferguson ((1896) 163 U.S. 537), which in 1896 had held that officially racially segregated public facilities did not violate the constitutional requirement of equal protection of the laws so long as the racially segregated facilities were physically or nominally equal, the court need not have claimed that the Plessy decision had no precedential weight. It could have claimed simply that precedent-based reasons are not conclusive, and that in Brown the precedent-based reasons for following the decision in Plessy were outweighed by, say, the moral and legal reasons in 1954 for ending official racial segregation in the public schools.
Yet although the content-independent reasons for following a precedent need not be absolute, in a domain in which a rule of precedent is actually operative it would be expected that over a long enough run of cases the reasons supplied by the principle of precedent would on occasion be outcome determinative. That is, we should expect that a court or judge who actually took the reasons supplied by the idea of precedent to provide content-independent reasons for making decisions that it or she otherwise thought mistaken would on occasion follow the precedent in spite of her or its content-based reasons for deciding otherwise. If such subjugation of first-order substantive reasons to the constraints of precedent never or rarely occurred—if a judge or court professed adherence to a norm of precedent but never reached outcomes other than those consistent with her or its content-based and all-things-considered substantive judgment—there would be reason to doubt that the norm of precedent was actually being internalized by the judge or court. This possibility, which is central to the Legal Realist claims about precedent which will be discussed in a subsequent section, should not be discounted, for claims of its empirical plausibility are far from frivolous. Nevertheless, as an initial matter we can still understand what a norm of precedent would do if it were operative, while temporarily delaying considering the extent to which, if at all, such norms are actually operative in various legal decision-making domains.
On Distinguishing Precedent from Analogy
In some of the literature on precedent and on analogy, arguments from precedent are equated with arguments from analogy (Holyoak 2005; Weinreb 2005), but this conflation is a mistake (Schauer 2008), albeit an understandable one. Because arguments from analogy are widespread in law, and because arguments from analogy typically use a previously decided case as the source of the analogy, commentators, especially those external to the legal system, assume that this form of argument is an argument from precedent, but doing so ignores the important differences between the two, and risks misunderstanding or misinterpreting the very idea of precedential constraint.
More specifically, an argument from analogy is ordinarily a form of persuasion and justification, but not of constraint. One making an argument from analogy typically finds an example, called the source in the literature on analogical reasoning, and then identifies some conclusion or characteristic about the source that both the user of the analogy and the object of the user–s argumentative or justificatory efforts will find appealing, and then calls forth a similarity between the source and the target, the current issue that is the subject of the argument from analogy (Gentner, Holyoak and Kokinov 2001; Holyoak and Thagard 1995). If the subject of the argument—those whom someone making an argument seeks to persuade—accepts the similarity, therefore, the subject may be persuaded that the similarity justifies treating the target case in the same way that the source case was treated. When President George H. W. Bush analogized Saddam Hussein to Adolf Hitler in order to justify intervention to prevent an Iraqi takeover of Kuwait, he asked his audience to recognize an important similarity between the two—that both were territory-expanding and highly dangerous dictators—so that someone who recognized the wisdom of stopping Hitler would similarly recognize the wisdom of stopping Saddam Hussein (Spellman and Holyoak 1992). And in law, the same argumentative maneuver is widespread. Consider, for example, Adams v. New Jersey Steamboat Company (1896) 45 NE 369), an 1896 case from the New York Court of Appeals (New York’s highest state court) in which the issue, arising out of a burglary on board, was whether a steamboat with passenger compartments was more like a train with sleeping berths, in which case the steamboat owner would be held to normal standards of negligence in determining liability, or more like an inn, in which case the substantially stricter liability standards for innkeepers would apply. In analogizing the steamboat’s passenger compartments to the inn and not to the train, the court identified similarities between the two—the presence of lockable doors, for example—and used those similarities to construct an analogy such that the same result reached for innkeepers would be the result reached for the operators of steamboats with passenger cabins.
Although the analogical form of reasoning exemplified by Adams is ubiquitous in law, the court’s argument was not an argument from precedent in the strict sense. The law relating to an innkeeper’s liability did not bind or otherwise constrain the New York court, as would have been the case had there been a previous decision, involving a different steamboat and a different burglary victim, by the very same court holding steamboat owners to the strict standards applied to innkeepers. Precedential constraint is about the obligation of a lower or subsequent court to reach the same result with respect to the same question as had been reached before or above, even if the judge in the instant case believed the previous or higher decision to be mistaken. But no such mechanism was at work in Adams. The court in Adams used the analogy to justify its chosen result, and not to explain why in fact it had no choice at all, as would have been the case were we talking about precedential constraint. And the advocates in Adams presumably each used analogical reasoning to try to persuade the court that the steamboat’s passenger cabins were more like rooms in an inn or, on the contrary, more like the open compartments on a train, but neither would have suggested that the court had no choice in the matter, as would have been the case had there been a previous decision on virtually identical facts, or had this been a lower court constrained to follow even those decisions of higher courts with which it disagreed.
Analogical argument, therefore, involves the selection of a source analog (which in legal argument is often but not necessarily a previously decided case) that the maker of the argument believes will be persuasive (Levi 1949), but genuine precedential decisionmaking is neither about choice nor persuasion. It is about constraint. If there is in fact a case “on point,” or “on all fours” (both common legal expressions) from a higher court, or from the same court on a previous occasion, the constrained court has little choice in the matter, and the core idea of precedent, the justifications for which will be considered in a subsequent section, is about the obligation of a court to make decisions, with which it may well disagree as a matter of substance, just because of the existence of the precedent.
That analogical reasoning and precedential constraint are commonly, even if mistakenly, conflated is likely a function of two different causes. First, in legal discourse the source analogs are frequently referred to as “precedents,” which in much of law is the umbrella term used to designate any previous decision of any court. It is not a linguistic mistake in legal argument to refer to a decision from another jurisdiction as a precedent, as in saying “there is precedent in Montana for this result” during an argument to a court in New Jersey, which is of course not bound by the Montana decision in any way. And because the word “precedent” is capacious in just this way, it encourages the failure to distinguish genuinely constraining precedents from those previous decisions of various courts that either did not deal with precisely the same question or did not emanate from a court whose decisions are binding on the court deciding the current case.