No empirical evidence supports it
Alexander Galetovic and Stephen Haber, 2017 - *Professor, Department of Economics, Universidad de los Andes, Santiago, Chile and **Peter and Helen Bing Senior Fellow, Hoover Institution, A.A. and Jeanne Welch Milligan Professor, School of Humanities and Sciences, Stanford University. “THE FALLACIES OF PATENT-HOLDUP THEORY” Journal of Competition Law & Economics, Volume 13, Issue 1, March 2017, Pages 1–44, https://academic.oup.com/jcle/article/13/1/1/3060409 //DH
At the same time that there are self-evident stelae contradicting patent-holdup theory, there is no positive evidence in support of its core predictions. Damien Geradin and Miguel Rato,24 Damien Geradin, Anne Layne-Farrar and Jorge Padilla,25 Vincenzo Denicolò, Damien Geradin, Anne Layne-Farrar, and Jorge Padilla,26 Richard Epstein, F. Scott Kieff, and Daniel Spulber,27 Kirti Gupta,28 Anne Layne-Farrar,29 J. Gregory Sidak,30 and Edward Egan and David Teece31 review the literature on patent holdup, patent thickets, and royalty stacking.32 All of these studies reach the same general conclusion, which is perhaps best summed up by Layne-Farrar: “Certainly the theories have been developed, but the empirical support is still lacking. Despite the fifteen years that proponents of the theories have had to amass evidence, the empirical studies conducted thus far have not shown that holdup or royalty stacking is a common problem in practice.”33