The Supreme Court's October 2017 term was not a modest one. In three of the Court's final decisions of the term, the Court overturned longstanding precedents in three significant areas. In Janus v. AFSCME, the Court overturned Abood v. Detroit Board of Education to hold unconstitutional mandatory agency fees for public sector workers. In South Dakota v. Wayfair, the Court overturned Quill Corp. v. North Dakota and National Bellas Hess Inc. v. Department of Revenue of Illinois to allow states to tax out-of-state internet retailers. And in Trump v. Hawaii, the Court announced that the infamous Korematsu decision was a dead letter. To some, this is all further evidence that the Roberts Court is an "activist" court, all-too-willing to depart from prior precedent to advance a conservative agenda.

The actual data tell a different story. The stark departure from stare decisis seen this past June was something of a departure for the Roberts Court -- at least as we have come to know it thus far. Under Chief Justice Roberts, the Court has largely maintained the status quo, and has generally avoided overturning prior court precedents. As I noted several years ago (drawing on a New York Times report), the early Roberts Court has overturned prior court precedents at a lower rate than its predecessors. From my 2010 post:

the Warren, Burger and Rehnquist Courts overturned precedents at an average rate of 2.7, 2.8 and 2.4 per term, respectively. The Roberts Court, on the other hand, has only overturned an average of 1.6 precedents per term. The record on striking down laws shows a similar pattern. The Warren, Burger, and Rehnquist Courts struck down an average of 7.9, 12.5, and 8.2 laws per term, whereas the Roberts Court has only invalidated an average of 3 laws per term.

Since that post, the Roberts Court has largely stayed the course. If anything, the rate has slowed a little bit.

There are various ways to measure the frequency with which the Supreme Court overturns prior precedents. The NYT report relied upon one methodology. Here is another.

The Government Printing Office keeps a record of when the Supreme Court overturns precedents. The latest compilation of overturned precedents is here. From this source, I looked at the rate at which the post-war Court has overturned precedents in two ways: 1) identifying the number of precedents overturned, and 2) the number of cases in which one or more prior cases were overturned. I made one correction for one error in which term a case was decided (Alleyne v. U.S., a Roberts Court decision listed earlier for some reason). I then added data for the October 2017 term. Counting Trump as overruling Korematsu, I included three overruling cases and four overruled cases for this term. By either measure, the findings reported by the NYT in 2010 remain true. If anything, the Roberts Court is more of an outlier.

Here is the data:

Terms Case
Overruled

Overruled
Rate/Term

Overruling
Cases
Overruling
Rate/Term
2010 NYT
Warren Court 15 64 4.27 45 3 2.7
Burger Court 17 70 4.12 52 3.06 2.8
Rehnquist Court 19 50 2.63 41 2.16 2.4
Roberts Court 13 18 1.38 13 1 1.6

By all three measures, the rate at which the Roberts Court overturns precedent is significantly below that of all three post-war predecessor courts.

Some caveats are in order. First, and most importantly, while this data tells us something about the general rate at which the Roberts court reconsiders and overturns prior cases, it tells us nothing about the relevant significance or importance of individual cases, i.e. whether overturning Quill in Wayfair is more or less significant than overruling Baker v. Nelson in Obergefell. Second, this data does not address the extent the Court may be departing from prior or widely held understandings of prior law. So, for instance, one can argue that the Roberts Court's decision in Shelby County v. Holder departed from prior precedent on the scope of federal power under the Reconstruction Amendments without overruling any prior precedents. This may be true, but this sort of change in the law would not show up in this analysis. Third, given the relative short time period, it's possible the Roberts Court data is artificially lowered by the brief period during which the Court only had eight justices. The Roberts Court may also be overturning fewer cases because it hears fewer cases, but it's not entirely clear which way this observation cuts.

One response to this data is to suggest that the reason the Roberts Court overturns so few precedents is because it followed the Burger and Rehnquist Courts. By this account, decades of Supreme Court dominance by Republican nominees left little work for the Roberts Court to do. This is a plausible hypothesis, but it does not appear to explain the data.

The Burger Court had a majority of Republican nominees, but it was not a particularly conservative court on most issues (it decided Roe v. Wade 7-2) and in many areas it did more to preserve or extend the jurisprudence of the Warren Court than to overturn it. The Rehnquist Court was more conservative in some areas, but remained liberal on others. Moreover, anyone who claims there aren't plenty of significant precedents that some conservatives would like to overturn has not been paying attention.

In both courts one finds that that cases overturning precedents moved in both liberal and conservative directions. For instance, the Burger Court overturned the "conservative" National League of Cities v. Usery decision with Garcia v. SAMTA. According to the NYT report above, only 60 percent of the Rehnquist Court decisions overturning prior precedents moved the law in a "conservative" direction. In other cases, it moved the law in a more "liberal" direction, sometimes by overturning the Rehnquist Court's own prior decisions, as in Roper v. Simmons (overturning Standford v. Kentucky) and Lawrence v. Texas (overturning Bowers v. Hardwick).

The big question is whether the Roberts Court's pattern of restraint will continue into the future. Changing the composition of the Court changes the Court's internal dynamics, including (potentially) the sorts of cases of the Court hears and its willingness to reconsider precedent. So it is entirely possible that a more conservative court will be more willing to overturn precedent. Is this likely? I am not so sure.

As I noted in a prior post, the early Roberts Court has been the Kennedy Court. When the Roberts Court overturned prior precedent, it was almost always because Justice Kennedy believed the prior case should be overruled. Justice Kennedy wrote the Wayfair decision and joined both Janus and Hawaii v. Trump. While there is reason to believe Chief Justice Roberts is reluctant to overturn prior precedent (given his general orientation toward preserving the status quo and avoiding disruption), this was not the case with Justice Kennedy. Where Justice Kennedy believed a prior case was wrong, he was rarely reluctant to support a reversal (Roe v. Wade being a possible, notable exception).

For the above reasons, I think it's unlikely that Justice Kennedy's replacement is more willing to overturn precedent than Justice Kennedy was. It is certainly possible, however, that Justice Kennedy's replacement is more willing to shift the law in a conservative direction. The key distinction here is that while Justice Kennedy was generally conservative and did not care too much about precedent, he sometimes wanted to push the law in a more liberal direction (as in Lawrence and Obergefell).

So, were I too make a prediction (not knowing who Justice Kennedy's replacement will be), I would predict that the Roberts Court is not likely to overturn precedents at a more rapid clip going forward, but where it overturns prior precedent, it may tend to do so in a more conservative direction. Of course, only time will tell.