Submarines in Software? Continuation Patenting in Softwarein the 1980s and 1990s and its Implications for Open Source

Stuart J.H. Graham, Walter A. Haas School of Business, University of California, Berkeley, and David C. Mowery, Walter A. Haas School of Business, University of California, Berkeley and the National Bureau of Economic Research (NBER)

1/01/2005
(Original Publish Date: 2002)

This paper examines the role of “continuations” (procedural revisions of patent applications) within software patents and overall patenting in the United States during 1987-99. Our research represents the first effort of which we are aware to analyse data on continuations in software or any other patent class, and as such provides information on the effects of 1995 changes in the U.S. patent law intended to curb “submarine patenting.” Our analysis of all U.S. patents issued 1987-99 shows that the use of continuations grew steadily in overall U.S. patenting through 1995, with particularly rapid growth in continuations in software patenting. Sharp reversals in these growth rates after 1995 suggest that changes in the U.S. patent law were effective. We analyse the role of continuation patents in creating opportunities for patentees to engage in strategic “hold-up” of software adopters and follow-on software innovators, and extend the analysis to open source software.