Posner is the author of the 4th most cited Law Review article in the field of intellectual property law[1]. Most telling of all is this statistic: "As of 2000, Judge Posner was the most often-cited legal scholar of all time with 7,981 citations, nearly 50 percent more than anyone else" [2]. He retains that position in 2012.
[1] - William M. Landes & Richard A. Posner, An Economic Analysis of Copyright Law, 18 J. Legal Stud. 325 (1989). [2] Fred Schapiro & Michelle Pearse, The Most Cited Law Review Articles of All Time, Michigan Law Review 2012.