Any idea how we might confirm which semesters each professor will be visiting elsewhere? I thought about calling the law school, but I don't know whether that's frowned upon for this particular issue..
I don't see why they would really mind; you could email Richardson. Leiter also modified his post:
UPDATE (5:30 pm July 16): Just to be clear--since several folks have e-mailed about this--not every visit, below, is for the entire academic year; indeed, my guess is at least half are not, meaning students can expect many of these faculty to *also* be teaching at their home institution. In the case of HLS, many of the visitors come in the Winter Term, i.e., just the month of January.
Or you could look at the schools' visiting appointments, although they are not completely clear:
http://www.law.harvard.edu/faculty/visiting (Gersen - Spring)
http://www.law.yale.edu/faculty/faculty.htm (Strahilevitz - Fall)