Management Science (accepted)

with D. Harhoff, S. Sorg and G. Von Graevenitz

We study the blocking effect of patents on follow-on innovation by others. We posit that follow-on innovation requires freedom to operate (FTO), which firms typically obtain through a license from the patentee holding the original innovation. Where licensing fails, follow-on innovation is blocked unless firms gain FTO through patent invalidation. Using large-scale data from post-grant oppositions at the European Patent Office, we find that patent invalidation increases follow-on innovation, measured in citations, by 16% on average. This effect exhibits a U-shape in the value of the original innovation. For patents on low-value original innovations, invalidation predominantly increases low-value follow-on innovation outside the patentee's product market. Here, transaction costs likely exceed the joint surplus of licensing, causing licensing failure. In contrast, for patents on high-value original innovations, invalidation mainly increases high-value follow-on innovation in the patentee's product market. We attribute this latter result to rent dissipation, which renders patentees unwilling to license out valuable technologies to (potential) competitors. 

Strategic Management Journal (forthcoming)

with H. Piezunka

We suggest that AI can help decision-makers learn; specifically, that it can help them learn strategic interactions by serving as artificial training partners and thus help them to overcome a bottleneck of scarce human training partners. We present evidence from chess computers, the first widespread incarnation of AI. Leveraging the staggered diffusion of chess computers, we find that they did indeed help chess players improve by serving as a substitute for scarce human training partners. We also illustrate that chess computers were not a perfect substitute, as players training with them were not exposed to and thus did not learn to exploit idiosyncratic (“human”) mistakes. We discuss implications for research on learning, on AI in management and strategy, and on competitive advantage.

Journal of Economics and Management Strategy (2023)

with L. Brachtendorf and D. Harhoff

Standard-essential patents (SEPs) have become a key element of technical coordination via standard-setting organizations. Yet, in many cases, it remains unclear whether a declared SEP is truly standard-essential. To date, there is no automated procedure that allows for a scalable and objective assessment of SEP status. This paper introduces a semantics-based method for approximating the standard essentiality of patents. We provide details on the procedure that generates the measure of standard essentiality and present the results of several validation and robustness exercises. We illustrate the measure's usefulness in estimating the share of true SEPs in firm patent portfolios for several telecommunication standards.

The Review of Economics and Statistics (2022)

with S. Wagner

Pharmaceutical firms enjoy market exclusivity for new drugs from concurrent patent protection and exclusivity of the clinical trials data submitted for market approval. Patent invalidation during drug development renders data exclusivity the sole source of protection and shifts the period of market exclusivity. In instrumental variables regressions, we quantify the effect of a one-year reduction in expected market exclusivity on the likelihood of drug commercialization. The effect is largely driven by patent invalidations early in the drug development process and by the responses of large originators. We provide estimates of the responsiveness of R&D investments to market exclusivity expectations.

Research Policy (2021)

with B. H. Hall and D. Harhoff

A “patent box” is a term for the application of a lower corporate tax rate to the income derived from the ownership of patents. This tax subsidy instrument has been introduced in a number of countries since 2000. Using comprehensive data on patents filed at the European Patent Office, including information on ownership transfers pre- and post-grant, we investigate the impact of the introduction of a patent box on international patent transfers, the choice of ownership location, and innovative activity in the relevant country. We find that the impact on transfers is small but present, especially when the tax instrument does not contain a development condition and for high-value patents, but that innovation as proxied by R&D and patents is not affected. We also find that introducing a patent box reduces patent transfers out of the country. These results call into question whether the patent box is an effective instrument for encouraging innovation in a country, rather than simply preventing or facilitating the shifting of corporate income to low-tax jurisdictions. 

Science Advances (2019)

with F. Poege, D. Harhoff and S. Baruffaldi

Despite decades of research, the relationship between the quality of science and the value of inventions has remained unclear. We present the result of a large-scale matching exercise between 4.8 million patent families and 43 million publication records. We find a strong positive relationship between the quality of the scientific contributions referenced in patents and the value of the respective inventions. We rank patents by the quality of the science to which they are linked. Strikingly, high-ranking patents are twice as valuable as low-ranking patents, which, in turn, are about as valuable as patents without a direct science link. We show this core result for various science quality and patent value measures. The effect of science quality on patent value remains relevant even when science is linked indirectly through other patents. Our findings imply that what is considered excellent within the science sector also leads to outstanding outcomes in the technological and commercial realms.

Berkeley Technology Law Journal (2017)

with J. Contreras, C. Helmers and B. Love

Despite the significance of patent litigation in the EU and the looming structural overhaul of the European patent litigation system, there has been comparatively little empirical or statistical analysis of European patent cases across member states. This absence has largely been due to the lack of harmonized case-level data across European jurisdictions. Over the past few years, however, researchers in Europe have developed patent litigation databases that have enabled robust quantitative analysis. As a result, comparative empirical studies have recently been published concerning European patent litigation overall, as well as litigation by so-called non-practicing entities (NPEs). The present study extends this work to the important area of litigation relating to standards-essential patents (SEPs) in the EU. We find that SEPs have been asserted in Europe at a significant level, and that PAEs play a large role in this activity.

European Journal of Law and Economics (2017)

with K. Cremers, M. Ernicke, D. Harhoff, C. Helmers, L. McDonagh, P. Schliessler and N. van Zeebroeck

We compare patent litigation cases across four European jurisdictions—Germany, the UK (England and Wales), France, The Netherlands—using case-level data gathered from cases filed in the four jurisdictions during the period 2000–2008. Overall, we find substantial differences across jurisdictions in terms of caseloads—notably, courts in Germany hear by far the largest number of cases, not only in absolute terms, but also when taking macro-economic indicators into account. Moreover, we show empirically that a considerable number of patents are litigated across multiple European jurisdictions; and further, that in the majority of these cases divergent case outcomes are reached across the different jurisdictions, suggesting that the long-suspected problem of inconsistency of decision-making in European patent litigation is in fact real. Finally, we note that the coming into force of the Unified Patent Court in Europe may, in the long term, help to alleviate this inconsistency problem.

Journal of Economic Behavior and Organization (2016)

with K. Cremers, D. Harhoff, C. Helmers and Y. Lefouili

In bifurcated patent litigation systems, claims of infringement and validity of a patent are decided independently of each other in separate court proceedings at different courts. In non-bifurcated systems, infringement and validity are decided jointly in the same proceedings at a single court. We build a model that shows the key trade-off between bifurcated and non-bifurcated systems and how it affects the incentives of plaintiffs and defendants in patent infringement cases. Using detailed data on patent litigation cases in Germany (bifurcated) and the U.K. (non-bifurcated), we show that bifurcation creates situations in which a patent is held infringed that is subsequently invalidated. We also show that having to challenge a patent's validity in separate court proceedings under bifurcation implies that alleged infringers are less likely to do so. We find this to apply in particular to more resource-constrained alleged infringers. Finally, we find parties to be more likely to settle in a bifurcated system.