PTLR Core Group Processed BibTeX

This page is part of the Patent Thicket Litature Review

Notes

This page contains the processed Core Group BibTeX entries.

The Processed Core Group BibTeX Records

@article{clarkson2004objective,
  title={Objective Identification of Patent Thickets: A Network Analytic Approach},
  author={Clarkson, G.},
  journal={Harvard Business School Doctoral Thesis},
  year={2004},
  abstract={},
  discipline={Econ, Law},
  research_type={Measures},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={}, 
  filename={Clarkson (2004) - Objective Identification Of Patent Thickets A Network Analytic Approach.pdf}
}

@article{clarkson2005patent,
  title={Patent Informatics For Patent Thicket Detection: A Network Analytic Approach For Measuring The Density Of Patent Space},
  author={Clarkson, G.},
  journal={Academy of Management, Honolulu},
  year={2005},
  abstract={When organizations in technology industries attempt to advance their innovative activities, they may encounter patent thickets, or dense webs of overlapping intellectual property rights owned by different companies that must be hacked through in order to commercialize new technology. Throughout the last 150 years, however, organizations have stumbled into a number of patent thickets and have occasionally responded by constructing patent pools or organizational structures where multiple firms collectively aggregate patent rights into a package for licensing, either among themselves or to any potential licensees irrespective of membership in the pool. Such collaboration among technologically competing firms, however, has often encountered difficulty from an antitrust standpoint, even if the formation of the pool is pro-competitive. Despite all that has been written lamenting the problem of patent thickets, the antitrust regime has never had an objective method of verifying the existence of a patent thicket in a given section of patent space. In response to the lack of such a methodology, this paper proposes a tool to facilitate objectively demonstrating the existence of patent thickets. This paper proposes a thicket identification methodology that uses a network analytic technique to determine if a patent pool is coincident with a patent thicket by comparing the density of the patent pool to the density of the surrounding patent space. This paper then applies the new methodology to two existing patent pools and verifies the existence of underlying patent thickets.},
  discipline={Law, Econ},
  research_type={Measures},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Clarkson (2005) - Patent Informatics For Patent Thicket Detection.pdf}
}

@article{clarkson2006problem,
  title={The Problem Of Patent Thickets In Convergent Technologies},
  author={Clarkson, G. and DeKorte, D.},
  journal={Annals of the New York Academy of Sciences},
  volume={1093},
  number={1},
  pages={180--200},
  year={2006},
  abstract={Patent thickets are unintentionally dense webs of overlapping intellectual property rights owned by different companies that can retard progress. This article begins with a review of existing research on patent thickets, focusing in particular on the problem of patent thickets in nanotechnology, or nanothickets. After presenting visual evidence of the presence of nanothickets using a network analytic technique, it discusses potential organizational responses to patent thickets. It then reviews the existing research on patent pools and discusses pool formation in the shadow of antitrust enforcement. Based on recent research on patent pool formation, it examines the divergent fate of two recent pools and discusses the prospects for the future formation of nanotechnology patent pools, or nanopools.},
  discipline={Mgmt},
  research_type={Discussion},
  industry={Nanotech},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Clarkson DeKorte (2006) - The Problem Of Patent Thickets In Convergent Technologies.pdf}
}

@article{cockburn2006entry,
  title={Entry and Patenting in the Software Industry},
  author={Cockburn, I.M. and MacGarvie, M.J.},
  year={2006},
  journal={NBER Working Paper},
  institution={National Bureau of Economic Research},
  abstract={To what extent are firms kept out of a market by patents covering related technologies? Do patents held by potential entrants make it easier to enter markets? We estimate the empirical relationship between market entry and patents for 27 narrowly defined categories of software products during the period 1990–2004. Controlling for demand, market structure, average patent quality, and other factors, we find that a 10% increase in the number of patents relevant to market reduces the rate of entry by 3%–8%, and this relationship intensified following expansions in the patentability of software in the mid-1990s. However, potential entrants with patent applications relevant to a market are more likely to enter it. Finally, patents appear to substitute for complementary assets in the entry process, because patents have both greater entry-deterring and entry-promoting effects for firms without prior experience in other markets.},
  discipline={Mgmt},
  research_type={Empirical},
  industry={Software},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Cockburn MacGarvie (2006) - Entry And Patenting In The Software Industry.pdf}
}

@article{cockburn2009patents,
  title={Patents, Thickets and the Financing of Early-Stage Firms: Evidence from the Software Industry},
  author={Cockburn, I.M. and MacGarvie, M.J.},
  journal={Journal of Economics \& Management Strategy},
  volume={18},
  number={3},
  pages={729--773},
  year={2009},
  abstract={The impact of stronger intellectual property rights in the software industry is controversial. One means by which patents can affect technical change, industry dynamics, and ultimately welfare, is through their role in stimulating or stifling entry by new ventures. Patents can block entry, or raise entrants’ costs in variety of ways, while at the same time they may stimulate entry by improving the bargaining position of entrants vis-à-vis incumbents, and supporting a “market for technology” which enables new ventures to license their way into the market, or realize value through trade in their intangible assets. One important impact of patents may be their influence on capital markets, and here we find evidence that the extraordinary growth in patenting of software during the 1990s is associated with significant effects on the financing of software companies. Start-up software companies operating in markets characterized by denser patent thickets see their initial acquisition of VC funding delayed relative to firms in markets less affected by patents. The relationship between patents and the probability of IPO or acquisition is more complex, but there is some evidence that firms without patents are less likely to go public if they operate in a market characterized by patent thickets.},
  discipline={Econ},
  research_type={Empirical},
  industry={Software},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Cockburn MacGarvie (2009) - Patents Thickets And The Financing Of Early Stage Firms.pdf}
}

@article{cockburn2011entry,
  title={Entry and Patenting in the Software Industry},
  author={Cockburn, I.M. and Macgarvie, M.J.},
  journal={Management science},
  volume={57},
  number={5},
  pages={915--933},
  year={2011},
  abstract={To what extent are firms kept out of a market by patents covering related technologies? Do patents held by potential entrants make it easier to enter markets? We estimate the empirical relationship between market entry and patents for 27 narrowly defined categories of software products during the period 1990-2004. Controlling for demand, market structure, patent quality, and other factors, we find that a 10% increase in the number of patents relevant to market reduces the rate of entry by 3-8%, and this relationship intensified following expansions in the patentability of software in the mid- 1990s. However, potential entrants with patent applications relevant to a market are 2-3 times more likely to enter it. Finally, patents appear to substitute for complementary assets in the entry process, as patents have both greater entry-deterring and entrypromoting effects for firms without prior experience in other markets.},
  discipline={Mgmt},
  research_type={Empirical},
  industry={Software},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Cockburn Macgarvie (2011) - Entry And Patenting In The Software Industry.pdf}
}

@article{cockburn2010patent,
  title={Patent thickets, licensing and innovative performance},
  author={Cockburn, I.M. and MacGarvie, M.J. and M{\"u}ller, E.},
  journal={Industrial and Corporate Change},
  volume={19},
  number={3},
  pages={899--925},
  year={2010},
  abstract={We examine the relationship between fragmented intellectual property (IP) rights and the innovative performance of firms, taking into consideration the role played by in-licensing of IP. We find that firms facing more fragmented IP landscapes have a higher probability of in-licensing. We observe a negative relationship between IP fragmentation and innovative performance, but only for firms that engage in in-licensing. In contrast, greater IP fragmentation is associated with higher innovative performance for firms that do not in-license. Furthermore, the effects of fragmentation on innovation also appear to depend on the size of a firm’s patent portfolio. These results suggest that the effects of fragmentation of upstream IP rights are not uniform, and instead vary according to the characteristics of the downstream firm.},
  discipline={Mgmt, Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Cockburn MacGarvie Muller (2010) - Patent Thickets Licensing And Innovative Performance.pdf}
}

@misc{cockburn2007patents,
  title={Patents and the Survival of Internet-related IPOs},
  author={Cockburn, I.M. and Wagner, S.},
  year={2007},
  abstract={We examine the effect of patenting on the survival prospects of 356 internet-related firms that IPO'd at the height of the stock market bubble of the late 1990s. By March 2005, nearly 2/3 of these firms had delisted from the NASDAQ exchange. Although changes in the legal environment in the US in the 1990s made it much easier to obtain patents on software and, ultimately, on business methods, less than half of the firms in this sample obtained, or attempted to obtain, patents. For those that did, we hypothesize that patents conferred competitive advantages that translate into higher probability of survival, though they may also simply be a signal of firm quality. Controlling for age, venture-capital backing, financial characteristics, and stock market conditions, patenting is positively associated with survival. Quite different processes appear to govern exit via acquisition compared to exit via delisting from the exchange due to business failure. Firms that applied for more patents were less likely to be acquired, though obtaining unusually highly cited patents may make them more attractive acquisition target. These findings do not hold for business method patents, which do not appear to confer a survival advantage.},
  discipline={Econ},
  research_type={Empirical},
  industry={Software},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Cockburn Wagner (2007) - Patents And The Survival Of Internet Related Ipos.pdf}
}

@misc{entezarkheir2010patent,
  title={Patent Thickets and Market Value: An Empirical Analysis},
  author={Entezarkheir, M.},
  year={2010},
  abstract={The pro-patent shift of the United States has created a patent thicket. This has made the use of other firms’ innovations more costly, due to higher transaction costs and the possibility of hold up. Using a panel data on publicly traded US manufacturing firms from 1979 to 1996, this study finds a negative impact from the patent thicket on the market value of the firm. I also find that firms with larger patent portfolios experience a smaller effect, likely because stronger bargaining position lowers the occurrence of the hold-up problem for these firms. The advantage of larger firms is even more prominent following the pro-patent shift. My results also capture heterogeneity in the impact of the patent thicket across industries.},
  discipline={Mgmt},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Entezarkheir (2010) - Patent Thickets And Market Value An Empirical Analysis.pdf}
}

@article{evans2004software,
  title={Software patents and open source: the battle over intellectual property rights},
  author={Evans, D.S. and Layne-Farrar, A.},
  journal={Va. JL \& Tech.},
  volume={9},
  pages={10--13},
  year={2004},
  abstract={In the wake of a series of court cases extending patents to software, open-source software proponents have proposed a number of arguments for limiting or even eliminating software patents. In particular, they claim that the U.S. Patent and Trademark Office (USPTO) has done a poor job of reviewing software patent applications, resulting in obvious, trivial patents. Open-source proponents also maintain that software patents hinder the standards-setting process important for high-technology industries, and that patents will lead to intellectual property rights “thickets” that slow down or stop the innovative process in the software industry. We evaluate these claims, examining relevant empirical evidence where available. While it is clear that problems exist with the patent-granting process, they do not rise to the level of justifying a ban on software patents. Instead, other reasonable––and far less drastic––measures are available. The USPTO has already begun reforms that should improve its software patent-review process. As for patent thickets, theory suggests they could form in the software industry, but empirical evidence suggests that in fact this has not occurred. Moreover, tools such as patent pools and cross-licensing can increase innovation sharing and are available to limit the development of thickets. While the academic literature is still debating the link between patents and innovation, patents have been shown to have some positive effects, including increased venture capital funding for small firms. In the end, reform is far more attractive than abolition, because it retains the good while minimizing the bad.},
  discipline={Mgmt},
  research_type={Discussion},
  industry={Software},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Evans LayneFarrar (2004) - Software Patents And Open Source.pdf}
}

@article{galasso2008patent,
  title={Patent Thickets and the Market for Innovation: Evidence from Settlement of Patent Disputes},
  author={Galasso, A. and Schankerman, M.},
  year={2008},
  abstract={We study how fragmentation of patent rights (‘patent thickets’) and the formation of the Court of Appeal for the Federal Circuit (CAFC) affected the duration of patent disputes, and thus the speed of technology diffusion through licensing. We develop a model of patent litigation which predicts faster settlement agreements when patent rights are fragmented and when there is less uncertainty about court outcomes, as was associated with the ‘pro-patent shift’ of CAFC. The model also predicts that the impact of fragmentation on settlement duration should be smaller under CAFC. We confirm these predictions empirically using a dataset that covers nearly all patent suits in U.S. federal district courts during the period 1975-2000. Finally, we analyze how fragmentation affects total settlement delay, taking into account both reduction in duration per dispute and the increase in the number of required patent negotiations associated with patent thickets.},
  discipline={Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Galasso Schankerman (2008) - Patent Thickets And The Market For Innovation.pdf}
}

@article{galasso2010patent,
  title={Patent thickets, courts, and the market for innovation},
  author={Galasso, A. and Schankerman, M.},
  journal={The RAND journal of economics},
  volume={41},
  number={3},
  pages={472--503},
  year={2010},
  abstract={We study how fragmentation of patent rights (‘patent thickets’) and the formation of the Court of Appeal for the Federal Circuit (CAFC) affected the duration of patent disputes, and thus the speed of technology diffusion through licensing. We develop a model of patent litigation which predicts faster settlement agreements when patent rights are fragmented and when there is less uncertainty about court outcomes, as was associated with the ‘pro-patent shift’ of the CAFC. The model also predicts that the impact of fragmentation on settlement duration should be smaller under the CAFC. We confirm these predictions empirically using a dataset that covers nearly all patent suits in U.S. federal district courts during the period 1975-2000. Finally, we analyze how fragmentation affects total settlement delay, taking into account both reduction in duration per dispute and the increase in the number of required patent negotiations associated with patent thickets.},
  discipline={Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Galasso Schankerman (2010) - Patent Thickets Courts And The Market For Innovation.pdf}
}

@article{george2006hiding,
  title={What Is Hiding in the Bushes-Ebay's Effect on Holdout Behavior in Patent Thickets},
  author={George, G.D.},
  journal={Mich. Telecomm. \& Tech. L. Rev.},
  volume={13},
  pages={557},
  year={2006},
  abstract={},
  discipline={Law},
  research_type={Discussion},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={George (2006) - What Is Hiding In The Bushes Ebays Effect On Holdout Behavior In Patent Thickets.pdf}
}

@article{geradin2007royalty,
  title={Royalty stacking in high tech industries: separating myth from reality},
  author={Geradin, D. and Layne-Farrar, A. and Padilla Blanco, A.},
  year={2007},
  abstract={A few recent contributions to the literature have claimed that in high-tech industries -- where innovation is often cumulative and products include many components protected by patents held by many different patent holders – the cost of obtaining all necessary licenses is too high. Some have even requested sweeping policy reforms to deal with the so-called royalty stacking problem. In this Essay we find that the empirical evidence – including new evidence for 3G telecom – does not corroborate the gloomy predictions of the proponents of the royalty stacking hypothesis. A careful look at the theoretical underpinnings of this hypothesis explains the lack of empirical support. First, three necessary conditions must be satisfied for a royalty stacking problem to exist: (a) innovation must be cumulative, so that the patents are complementary; (b) there must be many patents for a given product; and (c) the many patents must be held by numerous, distinct rights holders. Buy royalty stacking may not be a problem even if the three necessary conditions are met; i.e., the three conditions are necessary but not sufficient. Moreover, several market mechanisms, such as cross licensing or voluntary patent pools, can be used to mitigate the costs of multiple concurrent patent negotiations. We conclude that the so-called royalty stacking problem is more myth than reality and that there is no reason to adopt the dramatic reforms in antitrust and patent law that have been recently proposed.},
  discipline={Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Geradin (2007) - Royalty Stacking In High Tech Industries Separating Myth From Reality.pdf}
}

@article{geradin2008complements,
  title={The complements problem within standard setting: assessing the evidence on royalty stacking},
  author={Geradin, D. and Layne-Farrar, A. and Padilla Blanco, A.},
  journal={Boston University Journal of Science and Technology Law, Vol. 14, No. 2, 2008},
  year={2008},
  abstract={Royalty stacking, the most recent incarnation of the complements problem identified in the early 1800s by French engineer Augustine Cournot, has received considerable attention. The potential for royalty stacking within standard setting efforts arises from the fact that downstream manufacturing companies can face multiple upstream gatekeepers, each of whom must grant a license to their “essential” patents before the downstream firms can legally commercialize the standard. Some authors have claimed that in high-tech industries—which are frequently characterized by cumulative innovation, dispersed ownership of patents, and cooperative standard setting efforts—the cost of obtaining all necessary licenses is too high, such that innovation has been thwarted and consumers have been harmed. In this paper, we assess the case for royalty stacking within standards and find the evidentiary support weak at best. We note that the relevant question is not whether royalty stacking is possible, as the theoretical arguments behind it have withstood the test of time, but whether it is common enough and costly enough in actuality to warrant policy changes. The available evidence suggests not, implying that any policy changes aimed at solving royalty stacking are likely to cause more (unintended) harm than they cure.},
  discipline={Econ, Law},
  research_type={Discussion},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Geradin LayneFarrar PadillaBlanco (2008) - The Complements Problem Within Standard Setting.pdf}
}

@article{hall2005note,
  title={A note on the bias in Herfindahl-type measures based on count data},
  author={Hall, B.H.},
  journal={Revue D' Economie Industrielle, Paris Editions, Techniques Et Economiques},
  volume={110},
  pages={149},
  year={2005},
  abstract={A Herfindahl index of constructed from shares based on count data where the number of counts is small will generally be biased downward because of the statistical properties of count data and Jensen’s inequality. This note suggests a simple correction for the bias and illustrates its applicability when using measures based on patent data and patent citation data.},
  discipline={Econ},
  research_type={Measures},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Hall (2005) - A Note On The Bias In Herfindahl Type Measures Based On Count Data.pdf}
}

@article{hall2012study,
  title={A Study of Patent Thickets},
  author={Hall, B.H. and Helmers, C. and von Graevenitz, G. and Rosazza-Bondibene, C.},
  journal={Draft Report to the UK IPO},
  pages={1--66},
  year={2012},
  abstract={},
  discipline={Econ, Policy Report},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Hall (2012) - A Study Of Patent Thickets.pdf}
}

@article{hall2001patent,
  title={The patent paradox revisited: an empirical study of patenting in the US semiconductor industry, 1979-1995},
  author={Hall, B.H. and Ziedonis, R.H.},
  journal={RAND Journal of Economics},
  pages={101--128},
  year={2001},
  abstract={We examine the patenting behavior of firms in an industry characterized by rapid technological change and cumulative innovation. Recent survey evidence suggests that semiconductor firms do not rely heavily on patents to appropriate returns to R&D. Yet the propensity of semiconductor firms to patent has risen dramatically since the mid- 1980s. We explore this apparent paradox by conducting interviews with industry representatives and analyzing the patenting behavior of 95 U.S. semiconductor firms during 1979-1995. The results suggest that the 1980s strengthening of U.S. patent rights spawned "patent portfolio races" among capital-intensive firms, but it also facilitated entry by specialized design firms.},
  discipline={Econ},
  research_type={Theory, Empirical},
  industry={Semiconductor},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Hall Ziedonis (2001) - The Patent Paradox Revisited.pdf}
}

@article{hargreaves2011digital,
  title={Digital opportunity: a review of intellectual property and growth: an independent report},
  author={Hargreaves, I.},
  year={2011},
  abstract={},
  discipline={Policy Report, Econ},
  research_type={Discussion},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Hargreaves (2011) - Digital Opportunity.pdf}
}

@article{harhoff2008incidence,
  title={Incidence and Growth of Patent Thickets-The Impact of Technological Opportunities and Complexity},
  author={Harhoff, D. and Von Graevenitz, G. and Wagner, S.},
  journal={CEPR Discussion Papers},
  volume={6900},
  year={2008},
  abstract={We investigate incidence and evolution of patent thickets. Our empirical analysis is based on a theoretical model of patenting in complex and discrete technologies. The model captures how competition for patent portfolios and complementarity of patents affect patenting incentives. We show that lower technological opportunities increase patenting incentives in complex technologies while they decrease incentives in discrete technologies. Also, more competitors increase patenting incentives in complex technologies and reduce them in discrete technologies. To test these predictions a new measure of the density of patent thickets is introduced. European patent citations are used to construct measures of fragmentation and technological opportunity. Our empirical analysis is based on a panel capturing patenting behavior of 2074 firms in 30 technology areas over 15 years. GMM estimation results confirm the predictions of our theoretical model. The results show that patent thickets exist in 9 out of 30 technology areas. We find that decreased technological opportunities are a surprisingly strong driver of patent thicket growth.},
  discipline={Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Harhoff (2008) - Incidence And Growth Of Patent Thickets.pdf}
}

@article{harhoff2012conflict,
  title={Conflict Resolution, Public Goods and Patent Thickets},
  author={Harhoff, D. and Von Graevenitz, G. and Wagner, S.},
  journal={Public Goods and Patent Thickets (April 15, 2012)},
  year={2012},
  abstract={Litigation and post-grant validity challenges at patent offices provide an important mechanism for correcting erroneous patent grants. However, such challenges will only be initiated if the (expected) private gains from challenging a granted patent right exceed the respective costs. Two important aspects may influence the likelihood of challenges. First, there is a public goods problem: firms may refrain from challenges if they anticipate that others will also benefit from the revocation of a weak patent. Second, as more firms are caught up in patent thickets, challenges to weak patents will become too costly as they invite counter-challenges. We use data on opposition proceedings initiated against patents granted at the European Patent Office (EPO) to study the importance of these mechanisms. This paper identifies a significant increase in the incidence of opposition in technical fields characterized by high concentration of patent ownership. Additionally, in fields with a large number of mutually blocking patents, the incidence of opposition is sharply reduced, particularly amongst those firms that are caught up in and driving the growth of patent thickets. Thus, while post-grant reviews may help to resolve problems in some areas, they are less suited to deal with patent thickets and contexts with dispersed patent ownership. We discuss the implications of these results for efforts to deal with patent thickets and weak patents.},
  discipline={Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Harhoff VonGraevenitz Wagner (2012) - Conflict Resolution Public Goods And Patent Thickets.pdf}
}

@article{hegde2009pioneering,
  title={Pioneering Inventors or Thicket Builders: Which US Firms Use Continuations in Patenting?},
  author={Hegde, D. and Mowery, D.C. and Graham, S.J.H.},
  journal={Management Science},
  volume={55},
  number={7},
  pages={1214--1226},
  year={2009},
  abstract={Why do firms use continuations in the prosecution of their patents? Motivated by the widespread use of continuations by U.S. firms and the prominence of this procedure in U.S. patent policy debates, we investigate the influence of corporate and patent characteristics on the use of continuations. We employ novel data on applicants and their filings of three types of continuations—the continuation application (CAP), the continuations in part (CIP), and divisions—during 1981–2000 to distinguish among the motives for continuing patents. We find that CIPs are disproportionately filed by research and development-intensive firms that patent heavily, and that these continuations are more common in chemical and biological technologies. Patents issuing from CIPs cover relatively important inventions and their use appears consistent with a strategy of protecting “pioneering inventions.” In contrast, CAPs and divisions are associated with less important patents assigned to capital-intensive firms, particularly in computer and semiconductor fields, and appear to be used in defensive patenting strategies. We analyze the effects of the 1995 change in patent term, and find that the act reduced continuations overall and shifted the output of continuations toward less important patents.},
  discipline={Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Hegde Mowery Graham (2009) - Pioneering Inventors Or Thicket Builders.pdf}
}

@article{heller1998can,
  title={Can patents deter innovation? The anticommons in biomedical research},
  author={Heller, M.A. and Eisenberg, R.S.},
  journal={Science},
  volume={280},
  number={5364},
  pages={698--701},
  year={1998},
  abstract={},
  discipline={Law},
  research_type={Theory},
  industry={Biomedical},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Heller Eisenberg (1998) - Can Patents Deter Innovation The Anticommons In Biomedical Research.pdf}
}

@article{huang2009does,
  title={Does patent strategy shape the long-run supply of public knowledge? Evidence from human genetics},
  author={Huang, K.G. and Murray, F.E.},
  journal={Academy of Management Journal},
  volume={52},
  number={6},
  pages={1193--1221},
  year={2009},
  abstract={Knowledge-based firms seeking competitive advantage often draw on the public knowledge stream (ideas embedded in public commons institutions) as the foundation for private knowledge (ideas firms protect through private intellectual property [IP] institutions). However, understanding of the converse relationship—the impact of private knowledge strategies on public knowledge production—is limited. We examine this question in human genetics, where policy makers debate expanding IP ownership over the human genome. Our difference-in-differences estimates show that gene patents decrease public genetic knowledge, with broader patent scope, private sector ownership, patent thickets, fragmented patent ownership, and a gene’s commercial relevance exacerbating their effect.},
  discipline={Mgmt, Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Huang Murray (2009) - Does Patent Strategy Shape The Long Run Supply Of Public Knowledge.pdf}
}

@article{mann2004myth,
  title={The myth of the software patent thicket},
  author={Mann, R.J.},
  journal={bepress Legal Series},
  pages={183},
  year={2004},
  abstract={This paper is the first part of a wide-ranging study of the role of intellectual property in the software industry. The project focuses on the software industry because of the importance of that industry to the modern economy, because of the importance of innovation to that industry, and because of the well-known difficulties of accommodating traditional intellectual-property regimes (patent, copyright, and trade secret) to innovation in the industry. This paper focuses on innovation in the hundreds of small venture-backed firms that form the bulk of the population of the industry. After a brief description of the history of the industry in Part II, Part III discusses the evidence on which the paper relies: a set of about 50 interviews of industry executives – diversified geographically, by size of company, and by role in the industry (software developers, venture capitalists, lenders, etc.). Relying on those interviews, the paper provides a detailed explication of the role that intellectual property plays in the industry. Parts IV through VI of the paper organize the information from the interviews and situate it in the extensive literatures on venture capital investing, the economics of innovation, and patents. The first substantive topic of the paper (Part IV) is the features of startup firms that attract investment by venture capitalists – generally something about the startup that suggests a “sustainable differentiation” of the firm from its competitors. The differentiation could come from any number of advantages the firm has – a first-mover advantage, special skill of its employees, a unique approach to solving a difficult problem, or, in some cases, intellectualproperty protection.The second substantive part of the paper (Part V) discusses the role of copyright. The major point of this part is that copyright protection is of little value to startup firms. Copyright protection is designed to protect expression, and not functionality. Thus, it provides little of the protection for which venture investors are looking. The basic problem is that it does not offend copyright law if a competitor observes a software product and designs a new product that includes precisely the same functionality, so long as the competitor uses none of the “expression” from the first product. Because the competitor’s customers are for the most part interested in the functionality, not the expression, this is not an important constraint. On the other hand, copyright protection does provide important protections in other areas, most obviously in protecting the later-stage firm’s products from piracy. Generally, this part of the paper tells a story of unsuccessful efforts to stretch the copyright regime to do something it never was intended to do. The final substantive part of the paper (Part VI) discusses the role of patents. Because patents do protect functionality, they have at least the theoretical potential to provide the sustainable differentiation for which investors are looking. The problem, however, is that in many sectors of the software industry innovation is not of a character that a typical patent can protect a firm from competitors: often competitors would be able to design a competing product that works around a firm’s patent. Thus, despite significant increases in patenting in the industry, about 80% of venture-backed software firms do not obtain patents during the early years of their existence. The question, then, is what benefits patents do provide to those firms. This part explores several benefits, including the classic benefit of excluding competitors. In this industry at least, that benefit accrues primarily to small firms, protecting them from the competitive depredations of incumbents. Incumbents, by contrast, rarely use patents to exclude smaller firms from the industry. The part also discusses a series of less conventional benefits small firms gain from software patents: as barter in cross-licensing arrangements, in signaling their technical competence to third parties, in converting tacit knowledge into a verifiable and transferable form, and in making the firm attractive to potential acquirers. The paper closes by discussing the implications of the patent analysis for recent debates about the value of patents in the software industry. The paper starts with a discussion of theoretical literature suggesting that free availability of patented technology is important because of the software industry’s reliance on cumulative patterns of innovation. It then presents evidence about existing practices in the industry suggests that technology in fact is readily available, rebutting the prominent claims of a patent “thicket” that is supposedly stifling innovation in the industry. On the contrary, I argue, to the extent patents have an important effect in the industry, it is an effect that inures primarily to the benefit of the smaller firms trying to find a foothold from which they can compete.},
  discipline={Mgmt, Law},
  research_type={Discussion},
  industry={Software},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Mann (2004) - The Myth Of The Software Patent Thicket.pdf}
}

@article{nagaoka2006empirical,
  title={An Empirical Assessment of the Effects of Patent Thickets},
  author={Nagaoka, S. and Nishimura, Y.},
  journal={unpublished, Hitotsubashi University},
  year={2006},
  abstract={This paper investigates the effects of patent thicket, exploiting a unique measure of the patent thicket from an inventor survey and on data on the use of patents by around 1,200 Japanese firms. First, we develop an index of patent thicket in each industry, mainly using the size of complementary patents necessary for commercializing an invention, which is from the RIETI inventor survey. Secondly, we will assess empirically how “patent thickets” affect the patenting propensity and the use of the patents as well as whether it negatively affects the appropriability of the R&D. In such assessment, we focus on the interaction effects between the level of patent thickets and firm size, based on a theoretical view which patent thickets affect a large firm more, since the latter has a large stake for the prevention of a hold-up and has a larger demand for the combining patents. Focusing on the firm-industry interaction effects allow us to control for industry fixed effects. Major findings are as follows. Firstly, we have found that patent thickets are high in information and communication electronics equipment sector, information and communication sector and motor vehicles sectors while they are low in printing and food products industries. These results based on the average number of patents joint used for commercializing an invention are largely consistent with existing empirical studies on patent thickets. Secondly, we have found that patenting propensity increases more with firm size in the industry where patent thicket is high, controlling for industry fixed effects. Such effects do not exist among small firms. On the other hand, our findings suggest that a number of invention disclosures to the IPR department or that for applying a patent by a firm do not increase significantly more with firm size in the industry where patent thicket is high. Thirdly, we have found that while the proportion of used patents declines with firm † We would like to thank for valuable comments by the members of the research project at the Institute of Intellectual Property. We would like to thank for the Japan Patent Office for enabling us to use the firm level data of the Survey of Intellectual Property-Related Activities. 2 size, such effect is no stronger in the industry where patent thicket is high. One explanation for this is that cross-licensing is often a response for patent thicket problem. Cross licensing facilitates access to complementary technologies of other firms, which makes commercialization of own technology easier. We also find that while blocking increases with firm size, such effect is no stronger in the industry where patent thicket is high. We do not observe significantly larger negative effects of patent thickets on the patent use by every size of firms. Lastly, we have found that exclusively used patents make the largest contributions to a firms’ profit, in particular, more than cross licensed patents.},
  discipline={Mgmt},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Nagaoka Nishimura (2006) - An Empirical Assessment Of The Effects Of Patent Thickets.pdf}
}

@article{noel2006strategic,
  title={Strategic patenting and software innovation},
  author={Noel, M.D. and Schankerman, M.},
  year={2006},
  abstract={Strategic patenting is widely believed to raise the costs of innovating, especially in industries characterised by cumulative innovation. This paper studies the effects of strategic patenting on R&D, patenting and market value in the computer software industry. We focus on two key aspects: patent portfolio size which affects bargaining power in patent disputes, and the fragmentation of patent rights (.patent thickets.) which increases the transaction costs of enforcement. We develop a model that incorporates both effects, together with R&D spillovers. Using panel data for the period 1980-99, we find evidence that both strategic patenting and R&D spillovers strongly affect innovation and market value of software firms.},
  discipline={Econ},
  research_type={Empirical},
  industry={Software},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Noel Schankerman (2006) - Strategic Patenting And Software Innovation.pdf}
}

@inproceedings{regibeau2011assessment,
  title={Assessment of potential anticompetitive conduct in the field of intellectual property rights and assessment of the interplay between competition policy and IPR protection},
  author={Regibeau, Pierre and Rockett, Katharine},
  booktitle={Prepared for the European Commission, Publications Office of the European Union, ISBN 978-92-79-22210-8},
  year={2011},
  abstract={},
  discipline={Policy Report, Econ},
  research_type={Discussion},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Regibeau Rockett (2011) - Assessment Of Potential Anticompetitive Conduct.pdf}
}

@article{reitzig2004private,
  title={The private values of ‘thickets’ and ‘fences’: towards an updated picture of the use of patents across industries},
  author={Reitzig, M.},
  journal={Economics of Innovation and New Technology},
  volume={13},
  number={5},
  pages={457--476},
  year={2004},
  abstract={On the basis of a novel data set of 612 European patents and related inventions from five different industries, it is shown that multiple patents per invention are filed in both discrete and complex technologies. Multivariate analysis of the data suggests that in selected discrete technologies, patent ‘fences’ may serve to exclude competitors whereas in complex technologies, ‘thickets’ represent exchange forums for complementary technology. The results expand on traditional views of profitable patent exploitation across industries and elaborate on the most recent findings by Cohen et al. (Cohen, W.M., Nelson, R.R. and Walsh, J.P. (2000) Protecting Their Intellectual Assets: Appropriability Conditions and Why U.S. Manufacturing Firms Patent (or not). Cambridge, MA: NBER.) The analysis suggests that different legislative issues arise from multiple patenting per innovation in complex and discrete technologies depending on the degree of technological complementarity. The results have unexpected policy implications in that they illustrate how patentees could eliminate competition in the form of substitute technologies through fencing. They have wide managerial implications regarding the valuation of patent portfolios and the design of corporate IP strategies.},
  discipline={Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Reitzig (2004) - The Private Values Of Thickets And Fences.pdf}
}

@incollection{shapiro2001navigating,
  title={Navigating the patent thicket: Cross licenses, patent pools, and standard setting},
  author={Shapiro, C.},
  booktitle={Innovation Policy and the Economy, Volume 1},
  pages={119--150},
  year={2001},
  abstract={},
  discipline={Econ},
  research_type={Discussion, Theory},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Shapiro (2001) - Navigating The Patent Thicket.pdf}
}

@article{siebert2008does,
  title={Does Licensing Resolve Hold Up in the Patent Thicket?},
  author={Siebert, R. and Graevenitz, G.},
  year={2008},
  abstract={In a patent thicket licensing provides a mechanism to either avoid or resolve hold up. We study the choice between ex ante licensing to avoid hold up and ex post licensing to resolve it. Firms’ choice of licensing contract is studied in the context of a patent portfolio race. We show that high expected blocking leads to ex ante licensing while ex post licensing arises if expected blocking is low but realized blocking is high. Also, ex ante licensing reduces firms’ R&D incentives. A sample selection model of licensing is derived from the theoretical model. In this framework theoretical predictions on effects of blocking are tested with data from the semiconductor industry. We show that licensing helps firms to resolve blocking. However, licensing is not a cure all: it decreases as fragmentation of property rights increases and arises mainly between large firms with similar market shares. Using a treatment effects model we also confirm the prediction that ex ante licensing reduces the level of R&D investment.},
  discipline={Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Siebert Graevenitz (2008) - Does Licensing Resolve Hold Up In The Patent Thicket.pdf}
}

@article{siebert2010licensing,
  title={Licensing in the Patent Thicket-Timing and Benefits},
  author={Siebert, R.B. and Von Graevenitz, G.},
  year={2010},
  abstract={Complex high technology industries are increasingly affected by patent thickets in which firms’ patents mutually block the use of important technologies. Firms facing patent thickets patent intensively to acquire bargaining chips and use licensing to ensure freedom to operate. Such licensing allows rivals to either avoid or resolve hold-up from blocking patents. R&D incentives depend on whether licensing takes place ex ante or ex post. We model the choice between ex ante licensing and entry into patent portfolio races leading to ex post licensing. It is shown that higher degrees of blocking lead firms to license ex post, while stronger product market competition leads firms to license ex ante. Empirical results support these theoretical predictions.},
  discipline={Econ},
  research_type={Theory, Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Siebert VonGraevenitz (2010) - Licensing In The Patent Thicket Timing And Benefits.pdf}
}

@article{siebert2010jostling,
  title={Jostling for advantage or not: Choosing between patent portfolio races and ex ante licensing},
  author={Siebert, R. and Von Graevenitz, G.},
  journal={Journal of economic behavior \& organization},
  volume={73},
  number={2},
  pages={225--245},
  year={2010},
  abstract={Licensing can be a solution for hold-up in patent thickets. In this paper we study whether licensing is an effective solution for hold-up. To do this we distinguish between ex ante and ex post licensing. A theoretical model shows that firms’ expectations of blocking in a patent thicket determine whether they license ex ante while ex post licensing arises if expected blocking was low but realized blocking turns out to be high. It can also be shown that ex ante licensing will allow firms to reduce their patenting efforts. A sample selection model of licensing is derived from the theoretical model. Applying this to data from the semiconductor industry we show that licensing does help firms to resolve blocking. However, the probability of observing licensing decreases as fragmentation of property rights increases and arises mainly between large firms with similar market shares. Licensing experience is also an important determinant of licensing. As expected ex ante licensing allows firms to reduce the level of patenting.},
  discipline={Econ},
  research_type={Theory, Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Siebert VonGraevenitz (2010) - Jostling For Advantage Or Not.pdf}
}

@article{sternitzke2008visualizing,
  title={Visualizing patent statistics by means of social network analysis tools},
  author={Sternitzke, C. and Bartkowski, A. and Schramm, R.},
  journal={World Patent Information},
  volume={30},
  number={2},
  pages={115--131},
  year={2008},
  abstract={The present paper reviews the literature on social network analysis with applications to bibliometric data, and in particular, patent information. Several approaches of network analysis are conducted in the field of optoelectronics to exemplify the power of network analysis tools. Cooperation networks between inventors and applicants are illustrated, emphasizing bibliometric measures such as activity, citation frequency, etc. as well as network theoretical measures, e.g. centrality or betweenness. In this context it is found that inventors who serve as interfaces or links between different inventor groups apply for technologically broader patents, hence, benefiting from their access to different knowledge through their position. Furthermore, citation networks of patent documents as well as patent applicants were drawn. Here, patent thickets could be identified. The position of applicants within citation networks seems to be useful in explaining behaviour of the applicants in the marketplace, such as cooperation or patent infringement trials.},
  discipline={Econ},
  research_type={Measures,Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Sternitzke Bartkowski Schramm (2008) - Visualizing Patent Statistics By Means Of Social Network Analysis Tools.pdf}
}

@article{strandburg2006law,
  title={Law and the Science of Networks: An Overview and an Application to the ``Patent Explosion"},
  author={Strandburg, K.J.},
  journal={bepress Legal Series},
  pages={1617},
  year={2006},
  abstract={},
  discipline={Law, Econ},
  research_type={Discussion, Measures},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Strandburg (2006) - Law And The Science Of Networks.pdf}
}

@article{ukipo2011patentthickets,
  title={Patent Thickets: An overview},
  author={Intellectual Property Office Patent Informatics Team},
  journal={UK Intellectual Property Office},
  year={2011},
  abstract={},
  discipline={Policy Report},
  research_type={Discussion},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={UKIPO (2011) - Patent Thickets An Overview.pdf}
}

@article{von2011measure,
  title={How to measure patent thickets -- A novel approach},
  author={Von Graevenitz, G. and Wagner, S. and Harhoff, D.},
  journal={Economics Letters},
  volume={111},
  number={1},
  pages={6--9},
  year={2011},
  abstract={This paper provides a direct measure of the density of patent thickets based on patent citations. We discuss the algorithm that generates the measure and present descriptive results validating it. Moreover, we identify technology areas particularly affected by patent thickets.},
  discipline={Econ},
  research_type={Measures},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={VonGraevenitz Wagner Harhoff (2011) - How To Measure Patent Thickets  A Novel Approach.pdf}
}

@article{von2012incidence,
  title={Incidence and Growth of Patent Thickets-The Impact of Technological Opportunities and Complexity},
  author={von Graevenitz, G. and Wagner, S. and Harhoff, D.},
  journal={Journal of Industrial Economics},
  year={2012},
  abstract={We investigate incidence and evolution of patent thickets. Our empirical analysis is based on a theoretical model of patenting in complex and discrete technologies. The model captures how competition for patent portfolios and complementarity of patents affect patenting incentives. We show that lower technological opportunities increase patenting incentives in complex technologies while they decrease incentives in discrete technologies. Also, more competitors increase patenting incentives in complex technologies and reduce them in discrete technologies. To test these predictions a new measure of the density of patent thickets is introduced. European patent citations are used to construct measures of fragmentation and technological opportunity. Our empirical analysis is based on a panel capturing patenting behavior of 2074 firms in 30 technology areas over 15 years. GMM estimation results confirm the predictions of our theoretical model. The results show that patent thickets exist in 9 out of 30 technology areas. We find that decreased technological opportunities are a surprisingly strong driver of patent thicket growth.},
  discipline={Econ},
  research_type={Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={vonGraevenitz (2012) - Incidence And Growth Of Patent Thickets.pdf}
}

@article{ziedonis2004don,
  title={Don't fence me in: Fragmented markets for technology and the patent acquisition strategies of firms},
  author={Ziedonis, R.H.},
  journal={Management Science},
  volume={50},
  number={6},
  pages={804--820},
  year={2004},
  abstract={How do firms avoid being “fenced in” by owners of patented technologies used, perhaps unknowingly, in the design or manufacture of their products? This paper examines the conditions under which firms expand their own portfolios of patents in response to potential hold-up problems in markets for technology. Combining insights from transactions cost theory with recent scholarship on intellectual property and its exchange, I predict firms will patent more aggressively than otherwise expected when markets for technology are highly fragmented (i.e., ownership rights to external technologies are widely distributed); this effect should be more pronounced for firms with large investments in technology-specific assets and under a strong legal appropriability regime. Although these characteristics of firms and their external environments have been highlighted in the theoretical literature, prior research has not explored the extent to which such factors interact to shape the patenting behavior of firms. To empirically test these hypotheses, I develop a citations-based “fragmentation index” and estimate the determinants of patenting for 67 U.S. semiconductor firms between 1980 and 1994. Accumulating exclusionary rights of their own may enable firms to safeguard their investments in new technologies while foregoing some of the costs and delays associated with ex ante contracting.},
  discipline={Econ},
  research_type={Measures, Empirical},
  industry={},
  thicket_stance={},
  thicket_stance_extract={},
  thicket_def={},
  thicket_def_extract={},  
  tags={},
  filename={Ziedonis (2004) - Dont Fence Me In.pdf}
}