One minor related matter: I was surprised to see Charles Fried state that Elena Kagan had “resigned” as solicitor general in May 2010 and further surprised to see that Wikipedia makes the same assertion.

My understanding is that Kagan, at the request of the White House, stopped exercising most or all of the duties of her office—and in particular stopped taking on new cases—upon her nomination but that she continued as SG until she accepted her appointment to the Supreme Court on August 7, 2010. But I’m having difficulty finding anything authoritative on the point. (This SCOTUSblog post states that Kagan served as SG until August 2010.)

It wouldn’t have made much sense for Kagan to resign upon her nomination. That would have meant, among other things, that she wouldn’t be receiving a salary during the confirmation process.

Update: I now see that the website of the Office of the Solicitor General, consistent with my understanding, states that Kagan served as SG until August 2010.​