There is a great article from fivethirtyeight that walks through how swingy Roberts has been. Turns out he has joined liberals in 5-4 decisions a total of 5 times. Yes, he has sided with the liberals and against conservatives more than 5 times, but the reality is that as a Chief Justice Roberts has some special privileges, including being able to assign who writes majority opinions when he is on the winning side. This is laid out in another article also from fivethirtyeight. In the article Oliver points out that Roberts only shifted left starting in 2010. What happened at that time? Well, Obama’s two appointees were in 2009 and 2010. Yes, two liberals (Sotomayer and Kagan) replaced two other liberals (Souter and Stevens), but it is at least possible that Roberts no longer saw himself as a junior justice and was willing to use tactics to steer decisions. Interestingly this would have the effect of guaranteeing that majority conservative opinions were more frequently written by Alito, Scalia, and Thomas since Roberts would have been stepping in to make sure liberal decisions were written narrowly.
The reality is that this will be the first time when Roberts is able to act as a swing vote, and I personally don’t expect him to swing very much. In fact, the swing may actually be out of Robert’s hands to a certain extent. Whether to hear a case usually is decided by 4 justices, if 4 agree to hear a case then it is heard. With Kennedy on the court several cases were heard that should not have been (Prop 8 anyone?), while some others were not heard because Roberts and Kennedy did not want to be forced to take a stand. I can easily imagine Kavanaugh, Thomas, Alito, and Gorsuch deciding to hear cases that will force Robert’s hand on certain issues (Casey v Planned Parenthood anyone?). Roberts may believe in stare decisis, but the question will be when forced will he side with babies or with the 1990’s?
While the dock for 2018 is already largely decided, it will be interesting to see what happens in 2019 and beyond. In fact, if Ginsburg or Breyer are replaced by nominees in the mold of Gorsuch the whole discussion gets more interesting since the center position will move to Alito.