Scholars’ highlight: Consensus, disorder, and ideology on the Supreme Court

Despite broad areas of agreement that have emerged over the years, scholars and other serious observers of the Supreme Court remain far from unified in their understanding of what drives the Court’s decisions.  Few would maintain that we can say much useful about the Court’s decisions without considering the ideologies of individual Justices; far too much evidence has been amassed over the years showing that ideology has a substantial effect on their decisions.  (Imagine trying to predict how the Court will rule on the individual mandate without reference to the Justices’ deep-seated policy views.)  In fact, many scholars would maintain that ideology is so dominant that there’s not much point in paying attention to anything else.

To some scholars, including us, this last proposition seems to go too far.  Yet demonstrating this has proved notoriously difficult.   In our view, some of the difficulty arises from a tendency to think in overly general terms about how the Justices decide.  We believe that more progress can be made by investigating the possibility that Justices decide differently in different cases.  The article posted here is part of a larger project exploring that possibility.

In an earlier article we developed a method for measuring disorder, the degree to which the voting coalitions in a case depart from what we would expect if the Justices were voting along expected ideological lines: compare a five-to-four decision where the dissenters are Thomas, Scalia, Alito, and Roberts – consistent with expectations – with one where the dissenters are Thomas, Alito, Ginsburg, and Kagan – wildly inconsistent with expectations.  Now, the simple fact that Justices formed strange-looking coalitions in a case does not necessarily mean that their votes were not based on ideology, any more than the simple fact that they broke down along traditional ideological lines in another case necessarily means that their votes in that case were driven by ideology.  Nevertheless, one might expect that, on average, those cases exhibiting considerable disorder are driven less by ideology and more by other considerations. To ascertain whether ideology really does play a lesser role in the cases that result in disordered coalitions, we investigated the relationship between patterns of voting and case factors that should enhance ideology’s role in decisions.  We found that coalitions were more consistent with ideological voting in cases where we would expect ideology to have more impact, for instance in those the Court heard by choice (on certiorari), that involved constitutional issues, and where the Court overruled precedents.  In our view, this is strong evidence that cases do vary in the degree to which ideology dominates Justices’ decisions.

In the article featured here, we turn from the puzzle of strange coalitions in a Court where ideology is undoubtedly important to the puzzle of numerous highly consensual votes in that same Court.  In the fifty Terms running from October 1957 to June 2006, the Justices decided thirty-eight percent of fully argued cases without dissent.  In an additional eleven percent, only a single Justice dissented.

As common as these decisions are, scholars have given them little systematic attention.  We are not entirely sure why, but one likely reason is that they are generally not seen as worthy of special consideration.  For it may well be that the same forces that explain five-four and six-three decisions explain eight-one and nine-zero decisions – it is just that those forces push more Justices in the same direction in the cases that generate few or no dissents.

We think there are good reasons to question this one-size-fits-all account, especially to the extent it assumes that ideology always dominates Justices’ voting.  Consider, for instance, that a unanimous reversal at the Supreme Court could occur only if the lower court panel contained at least two judges who were both either more liberal or more conservative than even the most liberal or conservative members of the Supreme Court and were willing to court reversal with a decision unappealing to anyone on the Court.  Affirmances by a lopsided majority of the Court would require an ideologically divided Court to populate its docket with cases in which the lower court’s decision was obviously correct.  Neither of these events seems terribly plausible.

We suggest instead that cases with few or no dissents are systematically different from those that sharply divide the Court.  Specifically, we suspect that ideology tends to play less of a role in the former than in the latter.  We test this hypothesis by building on our earlier article, employing the same measure of the ideological disorder of the Justices’ voting coalitions to ask whether highly consensual decisions look more like those cases that produce ideologically strange coalitions or ideologically consistent ones.    It turns out that they look more like the cases that produce ideologically strange coalitions.  We view this result as substantial, albeit indirect, evidence that ideology is less dominant in decisions with larger majorities.

Because of what this finding indicates about both the nature of consensus and the reach of purely ideological models of decision making, we think it provides a strong argument for renewing scholarly attention to consensus on the Court.  More broadly, we think it demonstrates that we can gain a fuller understanding of Supreme Court decision making by recognizing that the influences on Justices’ decisions will vary from case to case.

Paul H. Edelman is a Professor of Mathematics and Law at Vanderbilt University; David E. Klein is an Associate Professor of Politics at the University of Virginia; and Stefanie A. Lindquist is Interim Dean and Professor of Law at the University of Texas.  The full version of their article, Consensus, Disorder, and Ideology on the Supreme Court, can be found here.