Justice Ginsburg has had quite a few health scares over the past little over a decade. She was diagnosed with pancreatic cancer in 2009 and subsequently resisted pressure to retire from the Court under Obama’s administration.  With multiple hospital stays this year and a recurrence of her pancreatic cancer, many question how long she will be able to stay on the Court and if she will outlast President Trump’s incumbency, while some liberals express frustration that Ginsburg did not retire under President Obama.

Retirements and replacements from the Court occur in different patterns. The current situation harkens back to Justice Thurgood Marshall’s retirement from the Court in 1991. Like Ginsburg, Marshall was a liberal leader on the Court. While Ginsburg spent her early years as a practitioner working for the ACLU, Marshall established the NAACP Legal Defense and Education Fund prior to his nomination to the Court.  Marshall’s health was in decline during the Reagan years and once George H.W. Bush was elected president, he might have guessed he would need to step down before the end of Bush’s minimally four years as president. Still, he was known to somewhat sarcastically confide to his clerks, “If I die, prop me up and keep on voting,” not wanting a conservative justice to be placed in his stead.  Marshall retired from the Court with Bush still president in October 1991 citing health and age.  He was replaced by Justice Clarence Thomas, one of the more conservative justices on the Court, leading to one of the biggest ideological shifts from retiring to replacing justice. 

An often used metric to depict ideological shifts in the Court is the Martin-Quinn (MQ) Scores.  While the MQ measures do not actually measure whether a justice is liberal or conservative, they do measure justices’ voting agreements with each other placing all justices on the same scale and bridging these agreement scores across time.  The statistical modeler needs to define liberal-conservative dimension by deciding on a prototypic liberal and conservative justice to sit on either side of the axis.  Since all justices are then on the same scale, the MQ Scores are not just pairwise measures between two justices.  MQ Scores are somewhat arbitrary in amount but they have never exceeded positive ten for conservative justices or negative ten for liberal justices. These bookends are meant to provide some sense of the score’s magnitude which is meaningful in a relativistic sense. Most importantly, close MQ Scores mean justices are well aligned in their voting while greater distance means they justices did not align very often in their votes.

The following graph shows the absolute values of the distance between Justice Thurgood Marshall and each of the justices on the Court in Marshall’s last term (1990) and then the distance between each of these justices and Justice Thomas in his first term on the Court (1991).

Two of the justices that stand out with this distance measure are Justices Rehnquist and Scalia. As both justices were predominately conservative in their votes, they tracked closely to Thomas which is evident from the low distance value. Contrastingly, these justices are the most distant justices from Marshall as Marshall was the most liberal justice on the Court at the time of his retirement.  Marshall, like Ginsburg, sat on a predominately conservative Court in his final years and was only in the majority 67.47% of the time in his final term on the Court.  Thomas was in the majority almost 10% more of the time in his first term on the Court at 76.77% of time.

A comparison will help underscore the importance of the value differences between Marshall, Thomas, and each of the justices. The next chart shows the transitions in score differences between Justice Kennedy in his final year on the Court and Justice Kavanaugh in his first year.  Justice Kennedy, was in the majority 92% of the time in his final term. He also tended to vote quite conservatively that term as evidenced by the fact that he voted with the conservative justices in all 14 5-4 decisions that broke down along ideological lines that term.  Kavanaugh was in the majority 88% of the time in his first term on the Court and was in seven conservative majorities in 5-4 decisions compared to the one occasion where he was the swing vote for the liberal justices. Not surprisingly then, Kennedy’s MQ Score differences in his final term on the Court tracked quite similarly to Kavanaugh’s in his first term on the Court.

Where does Ginsburg fit into all of this? Like Marshall, Ginsburg is a liberal justice on a predominately conservative Court. Her frequency in the majority from this past term is on the low end for the Court and is between those of Marshall in his last term on the Court and Thomas in his first.

Seven of the justices fall into a narrow band of frequencies between 72% and 78% for OT 2019. Only justices Roberts, Kavanaugh, and Gorsuch fall outside of this band at the higher end of the spectrum. Possibly more telling is the justices’ rates in the majority for 5-4 decisions during the 2019 term. 13 5-4 decisions were made across ideological lines. The five more conservative justices were in ten of the majorities. Roberts sided with the liberal justices in two of these decisions and Gorsuch sided with the liberals in one. One 5-4 decision, Georgia v. Public.Resource.Org, included justices of mixed ideologies in the majority. Ginsburg was in dissent in that case making her frequency in the majority 21% in 5-4 decisions this past term.

When we look at Ginsburg’s MQ Score differences from the other justices on the Court for the past two terms with released scores, OT 2018 and OT 2019, we see her proximity to the liberal justices and distance from the conservative justices — including from the three conservative justices most often in the Court’s majorities.

Ginsburg’s distance from Kennedy in 2017 is right on par with her distance from Kavanaugh in 2018. Both Kennedy and Kavanaugh were almost triple the distance away from Ginsburg as was any of the liberal justices.  This leaves a few possible scenarios for the future of the Court depending on how long Ginsburg remains.

Ginsburg needs to retain her spot on the Court until a new president is sworn in to ensure someone other than Trump fills her seat. If Trump or another republican president fills Ginsburg’s seat, chances are the justice will be at least as far to the right as Roberts and Kavanaugh and will very possibly be closer to edge of the continuum like Thomas and Alito. A few republican presidents have appointed justices that have drifted in the liberal direction over time, but this is unlikely given the vetting that goes into current nominations. This seismic shift would likely look like the transition from Justice Marshall to Justice Thomas.

If Ginsburg were to retire with a democrat president in office, her seat would likely be filled by a justice who aligns most closely with Justices Breyer, Sotomayor, and Kagan.  This would look a lot much more like the shift from Kennedy to Kavanaugh. 

Only time will tell how the future composition of the Court will look. The likelihood of Ginsburg remaining on the Court for another four years if Trump is reelected seems minimal.  Ginsburg’s health over the next five months and the results of the November election, both for president and for the Senate, will likely dictate if the Court takes an even sharper turn to the right, or if it remains at least somewhat similar to how it looks today.

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On Twitter: @AdamSFeldman