Ross E. Davies, of George Mason University School of Law, has a brief piece called "Law Review Circulation" available on SSRN. The article has been summarized by Inside Higher Ed, and, simply, reveals a serious drop in the the paid circulation for the "top 15" U.S. law reviews, where the figures are available (as they are required by the U.S. Postal Service to be).
One example will suffice here: The Harvard Law Journal's paid circulation over time was as follows:
1979-80: 8,760 \ 1987-88: 7325 \ 1997-98: 4367 \ 2007-08: 2,610
This is not surprising, perhaps, given the worldwide trend to moving data, scholarship included, into digital format. What is needed, Davies asserts, is good and reliable data from the publishers (and commercial republishers) as to electronic readership.
[via Digital Koans]