Guest post by Maveric Searle
This week we have a guest blogger, a Northwestern Pritzker law student, Maveric Searle, who developed a new measure of judicial ideology for a final paper in Tonja Jacobi’s Supreme Court cases seminar. He also applied it to the current Term, based on the limited decisions released so far, to answer the very pressing question of who we can expect to be the new median of the Court. Maveric has turned his paper into a ScotusOA post, providing the first take on the new ideological spectrum of the Roberts Court.
A new median
The retirement of Justice Anthony Kennedy in 2018 represented a potentially pivotal moment in the modern history of the Supreme Court. Kennedy had long held the spot of the median justice on the Court. The median justice, whose vote is often the deciding vote in contentious cases, is typically thought of as being the most powerful or the most influential justice. Kennedy’s retirement represented not only the appointment of a new justice, but also the opportunity for a new justice to fill the position at the Court’s center. Chief Justice John Roberts is commonly seen as the favorite to become the new median justice. This post analyzes the Court’s early rulings from the October 2018 Term to see if Roberts has lived up to those expectations, or if the Court’s newest member, Justice Kavanaugh, could be its new median.
Conceiving the Median: Agreeability and Majoritarianism
One simple way to identify the median justice is to look at who has voted in the majority most often this Term. The median justice should have a high rate of voting in the majority because historically the median is in the majority in closely decided cases more often than any other justice.
The numbers above suggest that the median is likely Kavanaugh or Roberts, each of whom has been in the majority at a higher rate than their colleagues. Kavanaugh has a higher ranking than Roberts, but importantly Kavanaugh did not participate in several cases this term, and a dissenting vote in any one of those cases would have moved him below Roberts.
Another straightforward approach is to look at how often each Justice agreed with the other Justices. The median justice should have a high agreement rate because, by virtue of being centrist, he or she will generally agree with colleagues on either end of the spectrum more often than will the opposite extreme justices.
Once again, Kavanaugh and Roberts are duking it out for top spot, tied for who looks most likely to be the median in terms of average agreeability rate. Given the similarities in both their rates of voting in the majority and their average agreeability rating, a more sophisticated analysis is needed to determine which of the two is the new median justice.
Ranking the Justices on a Left-Right Ideological Spectrum
It is now well accepted who is a liberal justice and who is a conservative justice, not only because the justices are nominated and confirmed by increasingly polarized political actors, but because each of the currently serving Justices has prior affiliations with either the Federalist Society or the American Constitution Society. The key question is: what are the differences among the liberals and among the conservatives? And in particular, with a new five justice conservative majority, who will be the most moderate conservative justice, and thus the median of the Court?
To identify the median justice by ideology along a left-right continuum, the next measure examines how often each justice votes with the conservative justices as compared to the liberal justices. Justices are classified as liberal or conservative based on the political party of the president who appointed them. It then counts how many liberal and conservative justices each justice agreed with in each case (using the percentage of the ideological bloc that the justice agreed with, to account for the fact that there are more conservative than liberal justices).
In a unanimous decision, every justice would agree with 100% of both the conservative and liberal justices. In a 5-4 ideologically ordered decision, a conservative justice would agree with 100% of the conservative justices and 0% of the liberal justices. In a case like Garza v. Idaho—a 6-3 decision with Thomas, Alito, and Gorsuch dissenting—each justice in the majority agreed with 40% of the conservatives (Roberts and Kavanaugh) and 100% of the liberals. Each justice in the minority agreed with 60% of the conservatives and 0% of the liberals. Justices are given weight for agreeing with themselves to ensure that decisions with a lone dissenter have an impact on the dissenting justice’s final score.
These percentages are then turned into an aggregated 0–1 “liberal score” and an aggregated 0–1 “conservative score,” with e.g. 60% agreement being a score of .6. A net ideology score is then determined by subtracting the liberal score from the conservative score for each justice. Using this method, unanimous decisions do not impact the final score because they result in an equal increase to both the aggregated liberal and the aggregated conservative score.
Finally, the net ideology scores are standardized by taking the final score and dividing it by the number of non-unanimous cases that each justice participated in. This yields a number between -1 and 1 for each justice, who can now be ranked them from left to right.
The resulting ranking lines up well with common intuitions, with the possible exception of Justices Gorsuch and Alito: Gorsuch lying slightly to the left of Alito may surprise some, particularly given Gorsuch’s emphasis on originalism and Alito’s rejection of that methodological approach most commonly associated with conservatism.
However, the scores may be capturing some nuance that would be missed by overly focusing on the two Justices’ rhetorical approaches, as there are some areas where Gorsuch has shown himself to be more liberal than Alito. For instance, in Biestek v. Berryhill, Gorsuch wrote a dissent that was joined by Justice Ginsburg. This dissent likely represents the two formalists agreeing based on factors that were methodological rather than ideological. Given the limited data available from the cases decided so far this Term, an unusual case like Biestek had a significant impact on Gorsuch’s final score: this decision alone moves Gorsuch from slightly to the right of Alito to slightly to the left. But Biestek may be quite representative: when it comes to matters of fairness—a key concept in the standard “underdog”–sympathetic model of liberalism—there is a strong argument to be made that Gorsuch lies to the left of Alito in some areas.
Unlike the statistics on justice agreeability and rate of voting in majority, the standardized ideology scores of Roberts and Kavanaugh demonstrate a significant difference between the two Justices. Although Kavanaugh has been in the majority at the highest rate, and he is tied with Roberts in terms of average agreeability, Roberts’ ideology score puts him distinctly to the left of Kavanaugh.
While it is still early in the post-Kennedy era of the Court, and a number of the Court’s most controversial cases have yet to be decided this term, this method suggests that Chief Justice Roberts will in fact be the Justice to look to as the Court’s new median. The early numbers suggest that we really are seeing “the Roberts Court.”