One thought that keeps crossing my mind as I research Justice Sutherland is whether this should be a book about the Four Horsemen. This sort of project would have several advantages. First, we think of these Justices as a group. Second, telling four stories may be better than one–there’s lots of personal detail in four stories that may be lacking otherwise.
What are the conceptual problems? One is that Justice McReynolds was a total jackass. Having to spend 25% of your book talking about a racist anti-semite is not much fun. (Sutherland, by contrast, was a gentle person who was well liked.) Another is that Justice Van Devanter wrote no significant opinions due to his writer’s block. No matter how important he was behind the scenes (and he was very important), that’s hard to illuminate. (I don’t know enough about Justice Butler to say whether he’s a good subject.)
Incidentally, Barry Cushman has a paper on SSRN talking about the law clerks of the Four Horsemen, if you’re interested.