I will admit I just made a mistake. Obama was a Senior Lecturer, regarded as a "professor" with a small p. He was certainly not regard as being on track for tenure, nor even full time.
"He was a Lecturer from 1992 to 1996. He was a Senior Lecturer from 1996 to 2004, during which time he taught three courses per year. Senior Lecturers are considered to be members of the Law School faculty and are regarded as professors, although not full-time or tenure-track. "
So, now we're down to Obama was considered to be a member of the University of Chicago Law School faculty. As we debate the relative chopse of various experts, do remind us again about Obama's experience actually practicing Constitutional Law before he ran for election.