This post is adapted from a law review article that may be downloaded here (citations available in the original).  

A unanimous judicial opinion admits little doubt about its authority.  Yet a dissent, especially when it is joined by another justice, deprives a majority opinion of its full import, calling into question the soundness and quality of the reasoning that prevailed in the case.  Future judges may, after all, reclaim from obscurity the rationale of a dissent, thereby abrogating the majority opinion against which the dissent was situated.  Concurrences and dissents notify future readers of alternative grounds of argument.  Concurrences may complicate the interpretation of the leading or majority opinion, but the fact that they signal the need for closer scrutiny and inspection is, in my view, advantageous.

Each case in a common-law system represents a ratified principle or principles nested within a chain of other cases.  Patterns of precedent gain increasing authority the longer and more widely they are followed.  Dissents add to the population of principles within the total system of rules that govern society, but they chart a path away from the settled course if they attract adherents and gradually disturb consensus about what the operative rule should be.

A decision in a single case may seem inconsequential because it is plugged into a vast network of cases.  Yet each case is important in the aggregate because it contributes to the wide distribution of choices by purposeful actors (voters who elect legislators, legislators who enact statutes, lawyers who contextualize statutes and produce lines of argument, judges who interpret statutes and formalize lines of argument, and litigants who initiate cases that either adopt or challenge prevailing rules).  Each case thus contributes to the filtering processes by which sketchy correspondences develop between past and present holdings.  Principles become clearer as associative links between cases grow more noticeable and as like cases combine into a cumulative force that demands attention.  Each case is necessary as a practical test for some principle to win judicial recognition.  A judge considers the law of the case synchronically, as if the operative rule were fixed, because he or she is bound by statute or precedent or some other source of positive law at that moment.  But concurrences and dissents, when they challenge the operative rule, force future judges to consider the law diachronically, as if it were subject to change and perhaps derived from some other source of law (e.g., when a judge dissents even though a statute or constitutional provision leads seemingly inexorably to the conclusion reached by the majority).

There are millions of published cases from both federal and state courts across the United States; the relation between principles and rationale in each of these cases cannot possibly be based on factual resemblances alone.  Only slight factual affinities, for instance, may lead judges to label an activity “theft” or “murder” in one case but not in another.  Cases do not consist merely of facts that require naming and classification according to a fixed legal lexicon.  The facts of a case may square with a legal principle that can be named, but the precise application of the principle remains unknown until a judge articulates it in an opinion.  The judge differentiates between principles in light of facts that are specific to each case.  The principles represent, in this sense, theoretical concepts abstracted from facts in specific cases.  When several cases hitch up to announce similar principles derived from comparable facts, the principles accrue authority.  Textual patterns signal how judges will rule in like cases; they thus ensure the predictability of rules.

The heritability of principles through cases enables judges to construct genealogies for principles to reveal a common ancestry.  An opinion represents one operative resolution among a heterogeneous mass of decisions.  An opinion in isolation derives its clarity and meaning by linking its rationale to associated concepts in prior cases.  Only by linking itself to like antecedents can an opinion establish its authority as the apparent sum of a limited number of legal options.  Case precedent is thus a social and discursive institution, embedding principles within a system or network of citation and imitation.  Each opinion unites certain principles with facts until eventually several opinions merge to form a cumulative family of similar cases.  Each opinion thereby serves as a resource for future judges who need to find and assemble principles that will situate the facts of a case within a settled pattern of decision-making.

Dissents are corrective mechanisms that guide future judges and justices away from problematic precedents.  They also facilitate and instantiate the values of free expression, as well as competition among ideas, that the First Amendment enshrines.  Justice William Brennan suggested that dissents involve “the critical recognition that vigorous debate improves the final product by forcing the prevailing side to deal with the hardest questions urged by the losing side.”  He echoed Justice Holmes by invoking “the conviction that the best way to find the truth is to go looking for it in the marketplace of ideas,” and to this end he referred to opinions figuratively as “the product of a judicial town meeting.”  Melvin Urofsky argues that dissents facilitate a “constitutional dialogue,” a phrase that “includes not just debates justices on the high court have with one another in specific cases or over particular jurisprudential ideas but also discussions between and among jurists, members of Congress, the executive branch, administrative agencies, state and lower federal courts, the legal academy, and last, but certainly not least, the public.”

The constructiveness of concurrences and dissents is evident from those which later courts have vindicated.  Examples include Justice Brandeis’s concurrence in Whitney v. California (1927) and his dissent in Olmstead v. U.S. (1928),  Justice John Marshall Harlan’s dissents in the Civil Rights Cases (1883) and Plessy v. Ferguson (1896), Justice Wiley Rutledge’s dissent in In re Yamashita (1946), and Justice Hugo Black’s dissent in Betts v. Brady (1942).  Recently the Supreme Court of Alabama released Ex parte Christopher (2013), a case that overruled a quarter-century-old precedent established in Ex parte Bayliss (1989).  Chief Justice Roy Moore, who authored the majority opinion in Christopher, had urged the overruling of Bayliss in a special writing he authored in Ex parte Tabor (2002).  Reanimating his Tabor writing in Christopher, the Chief Justice and a majority of the Court demonstrated the mode in which non-binding dissents may express reasoning that courts later adopt, in effect turning dead-letter into living authority.

Counterintuitively, a dissent may itself represent the plurality opinion.  In Ex parte Harper (2015), for example, Chief Justice Moore authored an opinion that drew only one concurrence as to the rationale.  Three other justices concurred in the result of the opinion but rejected the opinion’s rationale.  One justice recused from the case.  Justice Lyn Stuart authored a dissent that two other justices joined.  Thus, the dissent, with a block of three justices, had more support as to the rationale than did Chief Justice Moore’s rationale with which only one justice agreed.  Technically, then, the dissent carried more precedential weight than the opinion that disposed of the case.

The ideal of freedom of speech and expression is an inadvertent byproduct of the practice of dissenting, the primary function of which is to ascertain the proper legal argument, rationale, rule, or standard of review for a particular case.  A competition among values and ideas emerges inductively from the free play of clashing judicial opinions.  A variety or diversity of ideas embedded in case precedent enables a constructive flexibility in the rules that govern human activity.  By multiplying the options available to future judges, dissents ensure that courts have wider latitude to reach the right result in complex cases.  Dissents preserve in the textual record arguments that may in the long run seem more plausible, seemly, and correct.  They make it possible for future jurists to say, “This other argument is better and should be dispositive in the case before me.”