I’ve previously highlighted (in the “Sixth” point of my “Will the Left Oppose Elena Kagan?” post) the extraordinary recusal obligations that Elena Kagan, if appointed to the Court, would incur during her initial two or three years as a justice as a result of her service as Solicitor General. For some historical precedent on this question, let’s look to the last justice who was appointed to the Court from the position of Solicitor General, Thurgood Marshall.
Marshall served as Solicitor General from August 1965 to August 1967. He joined the Court on August 31, 1967. According to Lawrence S. Wrightsman’s The Psychology of the Supreme Court (p. 79), “Marshall recused himself from 98 of the 171 cases that were decided by the Supreme Court during the 1967-1968 term.” That’s 57% of the total. (Wrightsman states that “most of these were cases in which the federal government had been a party”; I suspect that all or nearly all of them were.)
One well-informed source tells me that the percentage of cases in which the United States takes part is much higher than in Marshall’s day and that in a recent term that figure approached 80%. My quick tally of the hearing lists for cases argued so far this term yields a figure of around 76%. It therefore may well be that Kagan, if appointed, would have to recuse herself from an even higher percentage of cases during her first term than Marshall did.*
I haven’t yet dug up statistics from Marshall’s second and third terms on the Court, but will pass them along if and when I do. (The slower pace of cases through the judicial pipeline provides another reason that Kagan’s recusal rate would probably be higher than Marshall’s for her second and third terms.)
* Because the Solicitor General starts making decisions on amicus participation well in advance of oral argument, the percentage of cases in which the United States would typically take part (either as party or amicus) is a good proxy for the percentage of cases in which a Justice Kagan (if expeditiously confirmed) would need to recuse herself for the first half or so of next term. Beyond that time frame, Kagan would still have to recuse herself in cases in which she participated (including when the United States was a party or amicus, or even considered amicus participation, at the federal appellate level or lower).