Here is Liebowitz's homepage, which has the reply. He has a link to copyright issues.
He also has a spreadsheet allowing you to play God with copyright. What are the underlying assumptions he uses? Are they sound (in the sense that logicians use the term--i.e., empirically true and logically valid)?
The Center for the Analysis of Property Rights and Innovation, which is located in the School of Management, at the University of Texas at Dallas, where he teaches, is pro-copyright. But that means anti-property rights, as I understand the term.