The Ideologies of Supreme Court Justices and Presidents

John Sides Apr 13 '10


In an earlier graph, I mapped the ideological “ideal points” of recent Supreme Court justices using scores developed by Andrew Martin and Kevin Quinn. Above is a similar graph using a different set of measurements developed by Michael Bailey at Georgetown. The data are here. Mike’s data are useful because they put presidents, members of Congress, and justices on the same scale and do so over time. This entails leveraging various kinds of “bridge” observations — actors who take positions on issues facing another institution (e.g, as Obama did when criticizing Citizens United v. FEC), actors who take positions on issues faced by earlier incarnations of their institutions (e.g., when Thomas expressed his view that Roe v. Wade was incorrectly decided). The details are discussed in this article (pdf).

Both graphs tell a somewhat similar story about the Court. There are clear differences between the conservative and liberal justices. Kennedy and O’Connor are in the middle. Stevens, the focus, starts toward the middle, moves left over time, and slightly back to the center toward the end of this period. The two graphs have their differences as well, but I think these are secondary.

The graph above also illustrates or confirms some interesting things about the relationship between the views of presidents and justices. As is well-known, several Republican appointees — Stevens and Souter for sure, but also Kennedy and O’Connor — were never as conservative as the president who appointed them and became somewhat less so over time. But other nominees worked out pretty well. Certainly Rehnquist, Scalia, Roberts, Alito, and Thomas had views similar (on average) to their patrons and, in general, to all the Republican presidents depicted here. Similarly, Clinton’s picks were similarly in step with him (again, on average).

Just for fun, I threw in a couple House speakers, Gingrich and Pelosi. It’s not surprising where they’re located, although Gingrich’s rightward movement is notable.