Public domain promotes efficient exploitation better than copyright

Paul J. Heald, Property Rights and the Efficient Exploitation of Copyrighted Works: An Empirical Analysis of Public Domain and Copyrighted Fiction Best Sellers, a preprint self-archived on January 9, 2007.  (Thanks to Lawrence Lessig.) 

Abstract:   Economists and policymakers have recently defended the extension of copyright protection to assure the efficient exploitation of existing works. They assert that works in the public domain may be under-exploited due to the lack of property rights or over-exploited due to congestion externalities. This study compares the availability, number of editions, and prices of 166 public domain bestsellers published from 1913-1922 with 168 copyrighted bestsellers from 1923-1932. It also compares the 20 most durable public domain works from 1913-1922 with the 20 most durable protected works from 1923-1932. A significantly higher percentage of the public domain books are still in print, with significantly more editions available per book, and for the sub-set of especially durable works, the public domain works are significantly less expensive. Although the data show that rates of availability for both kinds of books are likely sensitive to reductions in the cost of duplication and distribution, the study concludes that protection of fiction beyond the period necessary to ensure its creation is not justified by concerns about under-exploitation. The possibility of congestion presented by the data is also considered.