This past Supreme Court term saw a remarkable degree of unanimity among the justices as I and others pointed out. Should this continue, it would suggest that the Chief Justice has been successful at encouraging broader agreement on the Court.

Is all this agreement a good thing?  Adam Liptak reports on a new paper by Cass Sunstein suggesting that greater unanimity on the Court does not necessarily enhance the legitimacy, stability, or certainty of the law.  Here’s the abstract:

In 2013, the Supreme Court showed an unusually high rate of unanimous decisions – the highest, in fact, since 1940. This increase in unanimity, long favored by Chief Justice John Roberts, places a spotlight on an insufficiently appreciated fact: In 1941, the Supreme Court experienced a radical transformation. Almost immediately, it changed from a court that had operated by consensus, with very few separate opinions, into something closer to nine separate law offices, with a large number of dissenting opinions and concurrences, and with a significant rate of 5-4 divisions. Remarkably, the patterns established in the early 1800s continued until 1941, and the patterns established in the early 1940s have persisted to the present day. The transformation of 1941 appears to be attributable, in significant part, to the leadership style of Chief Justice Harlan Fiske Stone, who had no aversion to separate opinions and split decisions, and who was a frequent dissenter himself. The transformation offers general lessons not only about consensus and dissent within courts, but also about broader relationships among leaders, personnel, path dependence, prevailing norms, and the Court’s future. With respect to group behavior, it suggests the possibility of multiple equilibria: With small differences in leadership style and prevailing norms, the level of publicly expressed dissent can either grow or wither. With respect to the normative issues, the standard arguments in favor of a higher level of consensus within the Court – pointing to the values of legitimacy, stability, and minimalism – rest on fragile empirical foundations. It is true that a badly fractured Supreme Court can create uncertainty, and that internal divisions have costs as well as benefits, but there is no sufficient reason to hope for a return to the pre-1941 patterns.

Sunstein makes some important points.  Unanimity on the Court is not an unalloyed good. For instance, it’s certainly true that unanimous judgments do not always provide greater clarity.  The cost of broad agreement may be an opinion that speaks in generalities and pushes aside the potential points of disagreement.  Concurrences and dissents often draw clearer lines and are more analytically coherent than majority opinions.

The sorts of opinions that result from efforts to achieve greater unanimity are different from those that merely seek the median vote.  Not only are unanimous opinions less likely to be overturned, they are also less likely to overturn prior precedents in the first place.  Is this a good thing?  That depends on the extent to which one thinks the Supreme Court’s opinions should reinforce the status quo and, of course, which precedents are at issue.

At the same time, coalescing around a narrow holding allows the Court to avoid premature resolution of a potentially divisive question, perhaps leaving it to be resolved when it can be resolved in a unanimous way or even putting it off indefinitely.  This is itself a virtue of judicial minimalism, according to some, as there is no reason to think every important question must be decided by the Court — and by refraining from answering some questions, the Court may discourage potential litigants from needlessly stretching the bounds of what has been allowed (or prohibited) in the past.

So, is greater unanimity on the Supreme Court a good thing?  That depends.  But good or bad, it is a notable development, and it will have a significant effect on the law if it continues.