Welcome to the tenth installment of Predictions of the 10th Justice, brought to you by FantasySCOTUS.net. The league has approximately 4,000 members, who have made predictions on all cases currently pending before the Supreme Court.
In this installment, we will consider how likely each individual Justice will vote in the majority. be taking a closer look at predictions placing each justice in the majority and minority. Using the results from Citizens United, we will consider four of the biggest pending cases for this term, Quon, Christian Legal Society, McDonald, and Comstock, to show how predictions sort the Justices into majority and minority votes.

A majority ratio is calculated by dividing the number of predictions placing the Justice in the majority by the number of predictions placing the Justice in the minority. Using majority predictions over minority predictions allows us to state that for every prediction of a justice being in the minority, they will be predicted to be in the majority X times, which follows a standard statement of odds. For example, a ratio of 2 would indicate that the Justice is predicted to be in the majority two times for every one time they are predicted in the minority (2 Majority / 1 Minority). Conversely, a majority ratio of .5 would indicate that they are predicted to be in the majority once for every two minority predictions (1 Majority / 2 Minority). A majority ratio of 1 indicates that the Justice is predicted equally in the majority and the minority. The ratio is bounded on the lower end by 0, in the event the Justice is never in the majority. The ratio is bounded on the upper end by infinity, in the event the Justice is always in the majority. Try as he may, not even Justice Kennedy can achieve this lofty bound.

In Citizens United, the majority ratios are as follows:

Kennedy has the highest ratio at 7.01 (meaning for each minority prediction, he received 7 majority predictions. Roberts was next with 5.52, with Thomas, Scalia, and Alito coming in just under 4. It is obvious that predictions were made based on ideological blocs, since the liberal justices were predicted to be in the minority nearly twice as often as they were predicted in the majority. In this case, none of their ratios even approached 1, so there was no ambivalence about the Justices’ position. Based on the prediction information, we can also generate a second benchmark by multiplying the affirm/reversal percentages and the total number of votes, and using those results to create a majority ratio for comparison.
Multiplying the 908 total predictions by 62%, the percent of predictions for reversal, yields a numerator of 563. Multiplying the total predictions by 38%, the percent of predictions for affirmance, yields a denominator of 345. Dividing the numerator by the denominator would yield a ratio of 1.63. This is the reverse ratio, indicating the Justices in favor of reversal. Swapping the numerator and denominator yields a ratio of .61. This is the affirmance ratio, indicating the Justices in favor of affirming. As seen in Citizens, only the liberal Justices approached the comparison point, indicating that they were perceived as less likely to move out (or “defect”) of the minority, while the conservative Justices were more likely to join in with others in the majority.

How likely are each of the Justices to vote in Quon, Christian Legal Society, McDonald, and Comstock? Predictions of the 10th Justice, after the jump.

In Quon, Kennedy has a strong presence in the majority, and Ginsburg is most likely to be in the minority. Additionally, the majority/minority predictions hinge on ideological blocs. However, the 1.17 reverse ratio and 0.86 affirm ratio in this case show that the vote might not follow strictly along those blocs, with an unclear majority. The uncertainty surrounding this case is also shown by the ratios, due to how close they are to the neutral ratio of 1. The ratios indicate that the majority will be larger than just 5 justices due to all ratios being above 1.
In Martinez v. Christian Legal Society, Kennedy is predicted the most in the majority, though his ratio is much closer to the other Justices in this case. This case also slightly follows the ideological blocs, except that Roberts has a higher ratio than even the liberal Justices. In this case, the conservative Justices are predicted to be in the minority often. However, our threshold affirm ratio is 1.35, which only Scalia and Thomas drop below. Additionally, Thomas’ ratio of 1.14 indicates that he is coming close to the benchmark ratio of 1, meaning that members predict that Thomas could go either way, and in this case, he may be most likely to be in the minority. Based on the overall ratios, the lingering question for this case is which of the conservative judges will “defect” to vote in the majority.

In McDonald, Kennedy is again most predicted to be in the majority, and Ginsburg is least predicted in the majority. This case also splits directly down ideological blocs, with the conservative Justices all having ratios above 1 and liberal Justices having ratios below 1. Due to the distribution of predictions, our reverse ratio is a high 2.22 while the affirm ratio is 0.45. While the conservative Justices are well above the threshold, the liberal Justices are very close to their affirm ratio, indicating that there is little opportunity for “defection” from their stances.

Comstock, also presents interesting observations based on the majority ratios. Kennedy, as expected, is predicted to be in the majority the most, and this time, has a high ratio like in Quon. From an ideological standpoint, the liberal Justices are predicted more often in the majority, with the exception of Roberts who is equally predicted in the majority as Breyer, both of whom have the second highest ratio at 4. None of the Justices’ ratios are close to 1, indicating little uncertainty about the positions of the Justices. However, when compared with the 1.75 affirm ratio baseline, only Scalia and Thomas are below the ratio, indicating that they are not likely to “defect” to the majority. Thomas is the least likely to be in the majority. Alito, with a ratio of 2.28, is likely to move into the majority with the other Justices. An important lesson from the ratios for this case is that although ideology can be a useful guide for predicting outcomes, SCOTUS observers do not rely on it exclusively.

Overall, the majority ratios provide great insight when combined with other metrics. As noted in the above situations however, predictions (and by implication, the behavior of Justices) rarely conform to narrowly constructed situations where comparisons are easy. Understanding how our ratios gained from predictions differ from the benchmarks is important because it allows us to understand how the reality of perceptions and behavior differ from modeling, and which assumptions should be discarded. The narrowly tailored world where SCOTUS decisions are only 5-4 decision with stable majorities and only the outcome to decide is completely unrealistic when compared to the complexities of real world SCOTUS decisions. However, we can use the above information to show how relaxing the assumptions allows other factors such as group cohesion and specific affinities for certain areas of law to enter the prediction and decision process. For future case summaries, these ratios will be useful for determine how users perceive individual SCOTUS behavior in relation to majorities and case outcomes.

Many thanks to Corey Carpenter for his super assistance with this post.