The SCOTUS Tortoise And The Hare

The SCOTUS Tortoise And The HareWith nine justices on the Supreme Court, consensus among five justices is necessary for any successful voting coalition. Knowing this, there appears to be little incentive to vote alone.

Solo votes don’t have the power to generate precedent and do not even foreshadow any likelihood of gaining more adherents to such a view among a justice’s colleagues. Why vote alone then?

Perhaps because it showcases a justice’s unique jurisprudence. If certain justices’ interpretative methods differ from others, then their decisions in cases are likely to often differ as well. If justices are staying true to what they feel is proper interpretation, this may bring them to separate conclusions.

Sometimes, although not very often, these lone views slowly make their way into the Court’s set of majority doctrines. This appears to be the tale of the circuitous route of Justice Thomas to the helm of the Court.

Measuring Preferences

This is where a graphic measure can be helpful to develop inferences. The often cited political science metric for justices’ preferences, Martin Quinn (MQ) Scores, is useful for this endeavor. MQ Scores are dynamic as they differ for each justice, each term.

The input to develop these scores is justices’ pairwise voting. If two justices often vote together, their scores tend to run similarly. The more unique a justice’s voting behavior from the rest of the justices,’ the more likely their score will fall to one pole or the other. Similarly, if one justice often is in the majority (or shares votes with at least four other justices in most instances), they are more likely to fall towards the middle of the graph.


Justice Kennedy, the “swing justice” from 2005 until his retirement in 2018 was the pivotal vote in many cases and his generally fixed place in the Court’s majority led to his central position on the graph above. On the current Court, Justices Thomas and Sotomayor are the outliers on the current Court on outer edges of the liberal and conservative groupings (corresponding to the top and bottom of the vertical axis of this graph). Historically the greatest outlier among the justices was Justice Douglas whose dip in territory on the left is far more substantial than any other justice’s placement on the left or on the right.  Aside from Justice Rehnquist (as an associate justice), Justice Thomas is the farthest justice to the right.

The Justices’ Placements

Let me posit a bit more nuance to why justices fall towards the top or the bottom of this graph. Douglas as an outlier may have been due to his truly unique views on issues such as civil liberties, particularly as the number of conservatives on the Court grew in the years after the Warren Court. Another way to look at this is that Justice Douglas was less willing to compromise on his views to reach some agreement with other justices.

This may resonate with some of the current justices on the Court. Justice Sotomayor, for example, is by far the greatest critic of the death penalty on the Court.  Even though she often dissents alone on emergency applications, she does not seem to be swayed from continuing this practice. As the strongest liberal justice on the Court, this sometimes places her views on issues beyond the scope of agreement with the other liberal justices (we have yet to see how her votes will mesh with those of Justice Jackson).

Both Justices Thomas and Sotomayor, the two justices on the edges of the MQ ideological spectrum, were the most frequent solo voters last term, as both were the only dissenters in four cases apiece accounting for eight of the 11 such instances.


Thomas’s position on the right is a bit more complicated to explain. One might surmise that he is a more conservative voter than his counterparts. Still, on a Court that has been conservative on the balance since he joined in 1991, Thomas has had many stalwart conservatives alongside him including Justice Scalia and Justice Alito to name a few.

One might argue Justice Thomas’s views are more extreme than those of his colleagues in a manner similar to those of Justice Sotomayor. Along with Thomas falling to the far right though, he, like Justice Douglas on the left, seems to have views that others on the Court were not willing to at least outwardly share.  Those views are now surfacing in a way they never have before.

This was perhaps no more apparent than in Thomas’s concurrence in last term’s Dobbs opinion. Thomas wrote,

“As I have previously explained, ‘substantive due process is an oxymoron that ‘lack[s] any basis in the Constitution…’ The Court today declines to disturb substantive due process jurisprudence generally or the doctrine’s application in other, specific contexts…For that reason, in future cases, we should reconsider all of this Court’s substantive due process precedents, including Griswold, Lawrence, and Obergefell. Because any substantive due process decision is ‘demonstrably erroneous…’ we have a duty to ‘correct the error’ established in those precedents.”

Justice Thomas’s outspoken views on stare decisisqualified immunityadministrative agency deference, and affirmative action may be shared by his colleagues, but he also may well be the most outspoken on these issues in advance of the Court revisiting its takes on these doctrines (among others).

Thomas’s interjections in these areas raise a second type of a justice’s articulation of an independent view, which in this case is not reflected in MQ Scores — namely concurrences. If a justice has a unique view of jurisprudence and style of interpretation, one might expect that his or her rate of concurrences, which are more often than not solo opinions as well, to correlate with their rates of solo dissents.

Truly independent minds that are more concerned with getting things right according to their subjective views and principles will theoretically attach more importance to articulating their unique positions than in moderating their views to placate other justices and perhaps to find middle ground on the Court.


Concurrences and solo dissents weren’t always a Court fixture. Only in less than the last 75 years or so did these types of votes and opinions become more common. This is evident in the graph below depicting written concurrences per majority opinion across the Court’s history.


The rate has clearly climbed over time, but it seems to have steadied (albeit with some noise) since the 1960s, only jumping above .9 concurrences per majority opinion once, in 1993.

With this increasing rate it should not come as a surprise that the most justices with the highest levels of concurrences were on the Court after the 1950s. Below is a graph with some of the justices with the highest concurrence rates. It lists the highest ranking justices over time before the top ranking current justices and then includes current and recently retired justices.


Harlan 2 and Wiley Rutledge were known for their views that went beyond those of the majorities of the justices on their respective Courts even though their positions were not opposed to the outcomes that the majority of their fellow justices sought.  Like Justice Thomas, Justice Scalia was a staunch conservative on a conservative-centric Court. Justice Scalia’s positions often went beyond those of the Court’s majorities. Scalia, however, did not survive to see the fruits of all of his labors that may only become apparent with the current Court.

Stevens, on the opposite end of the ideological spectrum, often authored separate opinions whether he was in the majority or dissent. This isolated Stevens as liberal on a mainly conservative Court who still did not agree with the legal applications sought by the Court’s other liberal justices. Stevens also drifted ideologically over time (see the MQ Scores graph above), from a moderate justice to the farthest on the left. This also left much room for him to concur with decisions in the 1970s and early 1980s before Stevens became a liberal stalwart.

Thomas is atop the chart (vertically) for current justices. As his concurrence in Dobbs made clear, Thomas’ concurrences supply groundwork for future directions the Court may take now that it has a conservative supermajority.  This was emphasized earlier with his concurrence in Gamble v. United States where he wrote,

“In my view, the Court’s typical formulation of the stare decisis standard does not comport with our judicial duty under Article III because it elevates demonstrably erroneous decisions—meaning decisions outside the realm of permissible interpretation—over the text of the Constitution and other duly enacted federal law. It is always ‘tempting for judges to confuse our own preferences with the requirements of the law’…and the Court’s stare decisis doctrine exacerbates that temptation by giving the veneer of respectability to our continued application of demonstrably incorrect precedents.”

Not surprisingly, since the conservative justices have predominately held a place in the Court’s majority in recent years, the other justices with the highest concurrence rates are other conservative justices including Kavanaugh, Alito, and Gorsuch.

Thomas does not only rank on the higher end for concurrences, but also for solo dissents (the number of solo dissents were only catalogued from 8-1 split decisions so other dissents only signed by a justice but in cases with multiple dissents are not counted so the number of such instances is actually higher, although the rates should still be consistent across the justices).


Using a similar calculation to that for concurrences, this time with the number of solo dissents divided by the total number of authored dissents by a justice, the solo dissent rate is shown above (excluding justices with fewer than two solo dissents). Using the same contextual clues as I did above, we find that Thomas has the third highest rate of solo dissents in the Court’s history after Stevens and Rehnquist (with Rehnquist’s rate less than 1/100th higher than Thomas’s).

This measure also correlates strongly with the MQ ideological poles (shown by the MQ Score graph above) with Sotomayor’s rate not far below Thomas’s.  Thomas not only subtly hints that certain legal areas are in need of doctrinal change but has also emphasized this in several of his solo dissents. Although not the lone dissenter in June Medical v. Russo, his frustration with the Court’s abortion precedent was on full display when he declared, “Our abortion precedents are grievously wrong and should be overruled.” With Dobbs, Thomas got his wish. Now we will see if the 6-3 majority conservative Court goes after other decisions on Thomas’ list of poorly set out doctrine.

Before 2017 or so with the retirement of Justice Kennedy and with the confirmation of Justice Kavanaugh, many of Justice Thomas’s solo writings appeared to be extreme visions of where he desired the Court to go. When Justice Kennedy retired, Thomas became the most senior associate justice which meant he could assign majority opinions when he was in the majority and Justice Roberts was not.

This elevated his position among the conservatives in all such cases. With the overturning of abortion last term and the likely overturning of affirmative action precedent in higher education this year, the Court is poised to follow Thomas’s model of overturning decisions which he feels are predicated on fallacious reasoning. With a six-justice conservative majority for the foreseeable future, the Court can continue making this project a reality (much to the liberal justices’ chagrin).

Read more at Empirical SCOTUS….

Adam Feldman runs the litigation consulting company Optimized Legal Solutions LLC. For more information write Adam at [email protected]Find him on Twitter: @AdamSFeldman.