How Donald Trump’s election victories in 2016 and 2024 locked in a conservative Supreme Court

The fact that Donald Trump’s three appointments in his first term (Neil Gorsuch, Brett Kavanaugh, and Amy Coney Barrett) profoundly changed the Supreme Court is well known. But perhaps less appreciated is that these appointments, combined with Trump’s re-election in 2024, have likely locked in a conservative court for many decades. Our article in this symposium “The Supreme Court: How Did We Get Here? And What Comes Next?,” examines why and how the current conservative supermajority on the court came to be. In this post we summarize a set of simulations that suggest how profound and lasting an effect on the ideological trajectory of the Court Trump’s two terms have had and will likely have for years to come.

The statistical details of our simulation analysis can be found in Chapter 13 of our book, Making the Supreme Court: The Politics of Appointments, 1930-2020. But the basic idea is fairly straightforward. For any given year, we can take the current composition and project the composition going forward (we do so through the rest of this century). For every year, we then calculate the probability a justice will exit the court, based on their age, due to either death or retirement. We assume that justices will be more likely to time their retirement strategically—that is, retire when the president is of the same party---especially as they get older. Then, for each year, we calculate the probability that the president will be a Democrat or a Republican, based on past election results. Consistent with recent appointments, we assume that each new justice will be a reliable ideologue, meaning that Democratic-appointed justices would vote liberally, and similarly for Republican-appointed justices.

The result of this exercise is a series of “historical courts”—that is a court of nine justices of varying ideologies, based on the partisan composition of the court at any given time. To get at the inherent uncertainty in modeling the future this way, we ran this simulation 1,000 times, giving us 1,000 “courts” in every year; this allows for variation in new justices’ ideal points across the simulations, both because the party of the president will vary and because there is some within-party variation among Democratic-appointed judges and Republican-appointed judges (though, on average, Democratic justices will always be more liberal than Republican justices). For each simulation, we then calculate the ideology of the median justice, which is a nice summary statistic for thinking about the overall balance of the court.

Figure 1 summarizes the results of this exercise, depicting histograms of the distributions of the projected ideology of the median justice for the rest of the century. To make the results easier to digest, we aggregate the results by decade. For each decade, the horizontal axis captures the conservatism of the median justice, moving from more liberal to more conservative.

We present three counterfactuals. The left panel imagines Hillary Clinton had defeated Donald Trump in 2016. Assuming she would have been able to confirm Justice Scalia’s successor in her term, the simulations project a very liberal court for at least two decades. Of course, that did not happen. The second panel shows the simulations based on the Court as of 2021, following Trump’s first term. His three appointments, combined with the likelihood of strategic retirements going forward results in a mirror image of the Clinton winning scenario, showing a court that is projected to be conservative until at least the 2050s. The final panel shows the simulations as of this year: Trump’s reelection further shifts the projected conservative dominance of the court towards the end of the century.

To be sure, projecting American politics several decades into the future is a fraught exercise. But barring a string of unlikely events, the sliding doors election of 2016 and Trump’s return to office this year will almost certainly have a profound effect on the ideological composition of the Supreme Court for decades to come

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Article Details
The Supreme Court: How Did We Get Here? And What Comes Next?
Charles M. Cameron, Jonathan P. Kastellec
First published: June 13, 2025
DOI: 10.1177/00027162251324879
The ANNALS of the American Academy of Political and Social Science