This has led to the question of whether certain specialties are (or should be) differentially compensated within law schools. Brian Leiter has argued in the comments to this post -- admittedly based solely on intuition -- that tax and corporate law profs are more highly compensated than those who teach in other areas. I must say that I share this intuition and have no more data than Brian does. There's a great empirical study there waiting to happen.
In a way differential compensation within law schools is simply a more specific example of the differential compensation that law professors receive vis-a-vis others on campus: law professors have private sector options that sociologists don't; if law schools are to recruit and retain qualified applicants, they have to compensate them with these options in mind. If private law experts would have more options in the private sector than their public law counterparts, it would certainly make sense for them to be compensated accordingly.
Do we think this plays out in fact?