Prof. Geoff Stone argues that conservative Supreme Court justices are more ideologically inflexible and less meritocratic than their liberal counterparts. His evidence for this is that
Of the 20 law clerks appointed this Term by the five conservative Justices — Roberts, Scalia, Kennedy, Thomas and Alito, 18 of the 20 — or an astonishing 90 percent — clerked last year for a Republican-appointed judge. Of the 16 law clerks appointed this Term by the four more liberal Justices — Ginsburg, Breyer, Sotomayor and Kagan, only 9 of the 16 — or 56 percent — clerked last year for a Democratic-appointed judge.
I would not rest any theory on this information, but if I would, it could easily support quite different explanations.
1) Given that the court picks clerks every year, data from one year is not very interesting; there are no doubt fluctuations. Any serious discussion of the issue would require looking across a period of year. I understand Stone may not have wanted to this – any more than I do – but then it is probably not fair to say one year’s hiring “shows” anything. Prof. Brian Leiter surprisingly calls this “hiring patterns,” but I don’t see how one year can be a pattern.
Indeed, the numbers Stone cites sound impressive in terms of percentages, but are really just a difference of a few clerks. Stone admits this is just a “tidbit,” but then goes on to say it “reveals… what is really going on.”
2) Now assuming this “pattern” is true, one possible explanation is that there is more conservative-to-liberal drift on the bench than vice versa. Thus there are more Republican-appointed judges with liberal tendencies than vice-versa.
3) Perhaps Stone should have called his article “The difference between conservative and liberal JUDGES.” The relatively high rate of liberal justices recruiting from Republican-appointed judges could simply mean the latter are simply perceived as better judges, mentors, etc. than their Democratic-appointed counterparts. The circuit judge one clerks for is principally seen as a screen or proxy for the quality of the clerk. The datum is equally consistent with liberals recognizing that Republican appointed-judges attract better clerks.
4) There has been significantly greater proportion of Republican-appointed judges on the courts of appeals over most of the past two decades. This is the period during which current judges have built their reputation, and Republicans have had a quantitative edge. While this difference has closed in recent years, I assume newly-appointed judges will on the whole do worse in feeing clerks to the Supreme Court.