Who is the most powerful Supreme Court Justice on the current Court? This question, while interesting to think about, leads to several subsequent questions, primarily to do with what is meant by “powerful.” The vagueness with which we define power leads to a near impossibility in coming up with a legitimate and valid answer. Other studies have tried to define the greatest justice, a similarly vague concept, using This cut at the power index is focused on the current-ish Court which consists of the current term and the two previous. The justices on the Court for these three terms were all the same aside from the shift from Justice Breyer to Justice Jackson at the beginning of the 2022 Term.
The matrix defining the justices’ points is also based on the assumption that power relates to the rule of law. The more a justice does to defining or transforming the rule of law, the more the consequent power of the justice in a given instant. Each vote in each case is counted for this exercise and weighted based on whether a justice authors an opinion, votes in the majority, concurs, or dissents. Dissents are all counted as (-1) points because they actually argue against the rule of law established in a case. Concurrences are not weighted as heavily as majority votes because they argue for a rule of law that can be distinguished to some degree from that articulated in the majority opinion. While concurrences have differential levels of disagreement with the views of the majority, I’ll save gradations in concurrences for another day.
Defining Power
The power matrix is a simple point system based on the size of the majority and the vote or action of the justice. Beginning with the bottom tier, the points look as follows –
Dissents: (-1) points in all instances
9-0: Majority author (2 points), majority vote (2 points), concurrence (2 points)
8-1: Same as above
7-2: Majority author (4 points), majority vote (3 points), concurrence (2 points)
6-3: Majority author (5 points), majority vote (4 points), concurrence (3 points)
5-4 (or 4-3): Majority author (6 points), majority vote (5 points), concurrence (4 points)
Plurality votes: treated at the same point value as concurrences.
The votes are tallied for each justice and then averaged since each justice does not necessarily vote in each case. The average also allows for comparisons between justices on the Court for differing amounts of time since the points are normalized by justice.
There are some problems created between different time periods though. Consensus was more common on past courts making power harder to define. A counterargument though is that justices did not historically need the same amount of power to control the Court since disagreements were less common. Moving earlier in time, prior to 1869 the size of the Court ranged from five to ten justices, and so the point matrix would have to be refined to incorporate previous sizes of the Court.
There is one more point of contention in the current matrix which is what to do about the Chief Justice. The Chief’s most important power that is distinct from those of most other justices is the assignment power when the Chief is in the majority. If the Chief is not in the majority the assignment power goes to the senior most associate justice in the majority. There is a debate about what this power portends for the assigning justice, although some (like Lax and Cameron in this paper) argue that this power can be leveraged to bring the majority in the assigner’s favor in close cases, if the assigner is willing to delegate some authority in the decision to a justice whose vote was on the fence. If the power of assignment gives the assigning justice additional power, then it needs to be built into the model as well. Since this power is less clear and consistent than traditional voting power though, I created a separate index that takes assignment power into account by giving each assigning justice in each case one additional point.
The Results
The current Court is defined as beginning in 2020. 2020 was an important year for the Court because the center of the Court took a dramatic shift. A prior shift occurred in 2018 when Justice Kennedy retired, and Justice Kavanaugh moved the Court rightward. Since Kennedy was a right-leaning justice though and was replaced by a farther right-leaning justice, this shift was not as consequential as was the next one. In 2020, after Justice Ginsburg passed away and was replaced by Justice Barrett, the Court dramatically moved from a 5-4 conservative majority with Roberts as the potential swing vote, to a 6-3 conservative majority with Roberts and Kavanaugh in the center of the Court. This six justice conservative majority is also uniquely powerful relative to any other modern Court era.
Since 2020 then, how do the justices line up? If we do not factor in assignment power, the top of the index is quite close as shown below:
The normal index would place Justice Kavanaugh just a smidge above Justice Roberts and a bit above Justice Barrett. All other justices are much lower on the scale with Justice Thomas at the bottom.
When the assignment power is added into the model, the differential in justice power is more distinct.
In this model Roberts is the clear leader. This is consistent with some of the current coverage of the Court in the press although Roberts’ role in all of this is really debatable since the more conservative justices could still gather a 5-4 majority without him as they did in Dobbs.
Evaluating the Models and Concluding Thoughts
Whether Kavanaugh is the most powerful judge on the current Court is contestable. He is clearly garnering coverage in the press ranging from criticism to frustration with others looking at the new power structure on the Court with Kavanaugh front and center. While there has been little praise or adulation for the justice, there are though who have found helpful nuance in his separate opinions.
Placing Kavanaugh as the most powerful justice echoes how many opined about his predecessor, Justice Kennedy. Justice Kennedy was the clear swing justice on the Court from 2005 until he retired in 2018. Kennedy commanded this power because he was the fulcrum of votes in 5-4 ideologically split cases shifting some votes in favor of the more liberal leaning justices and others to the conservatives. Since Kavanaugh is arguably at least somewhat more conservative than Roberts, this would place him as the Court’s median that could swing the Court towards the liberals or conservatives in closely split decisions. The magnitude of difference between Kennedy and Kavanaugh on this index over time is still large if the number of terms is expanded to include those previous to when Kennedy retired as is consistent with the larger role Kennedy played as the swing justice.
While this model clarifies the relative power of the justices on the current Court, it comes with several caveats. One caveat is that the index only weights power based on the vote split in the case. Other ways to add depth into this picture, which might be added in subsequent articulations of this index include looking at when precedent is overturned or when a law is held unconstitutional, and looking at relative case importance by a measuring media coverage (like this measure developed by Clark, Lax, and Rice).
This model also does not consider either case selection or decisions made outside of the Court’s merits docket. While these factors do not likely have a great impact when comparing the justices across the three most recent terms, they could lead to some disagreements over the depiction of the justices across history and between different swaths of time.
Adam Feldman runs the litigation consulting company Optimized Legal Solutions LLC. For more information write Adam at [email protected]. Find him on Twitter: @AdamSFeldman.
