Learning by Suing: Structural Estimates of Court Errors in Patent Litigation

This paper presents structural estimates of the probability of validity, and the probability of Type I and Type II errors by courts in patent litigation. Patents are modeled as uncertain property rights, and implications of the model are tested using stock market reactions to patent litigation decisions. The estimation quantifies beliefs about patent validity and court errors in a Bayesian context. I estimate that the underlying beliefs about validity range from 0.6 to 0.7 for litigated patents. Market beliefs about courts show that Type I errors (finding a valid patent invalid) occur very frequently–an estimated probability of 0.45. However, Type II errors (finding an invalid patent valid) occur with near zero probability. Additional implications of the model address patent value. My results are the first structural estimates of court errors. Additionally, this study is the first to perform event studies on patent litigation.

The dynamics of patent citations

The use of patent citations as a measure of patent "quality" increased dramatically in recent years. I estimate the hazard of patent citation, and find evidence of unobserved heterogeneity. Hazard estimation provides a means to separate patent quality from citation "inflation."

Kelo, Cuno, and the Broken Window

In June 2005, the Supreme Court made one of its least popular decisions in recent history. In Kelo v. New London, the Court missed a simple point: that local decision makers make local decisions.

Bargaining in the shadow of precedent: the surprising irrelevance of asymmetric stakes

We develop a model of bargaining and litigation in the context of patent licensing (or any contractual setting). Following Priest and Klein (1984) we developed a model that explicitly allows for (1) multiple parties (leading to asymmetry of stakes), (2) binding precedent, and (3) pre-dispute bargaining done in the “shadow” of precedent-setting courts. The pre-dispute bargaining creates an endogenous opportunity cost of litigation for both plaintiff and defendant; i.e., the harm is endogenous. We show that the effects of asymmetric stakes on the litigation rate and plaintiff win rate are offset by opportunity costs (forgone licensing). That is, the degree of asymmetry does not appear to substantially impact the rate of litigation or the observed win rate of plaintiffs at trial. This result is in stark contrast to the previous theoretical literature, and has implications for interpreting the empirical literature.

The option value of patent litigation: Theory and evidence

In this paper I present a real options model of patent litigation when patents are not perfectly enforceable. I consider both finite horizon and infinite horizon models. The theoretical results demonstrate that patent value depends not only on the underlying technology, but also on the degree of uncertainty over the property right. Additionally, uncertain property rights create an effective patent term that is less than the statutory term. Using simulation methods and patent data, I estimate the hazard rate of patent litigation. I find that, contrary to previous results, the most valuable patents are not the primary candidates for litigation

The value of certainty in intellectual property rights: stock market reactions to patent litigation

Using a sample of patents litigated between 1977 and 1997, I estimate stock market reactions to patent litigation decisions and to patent grants. I find that the resolution of uncertainty over validity and infringement is worth as much to the firm as the initial patent right. Each is worth about 1 to 1.5% excess returns. Additionally, I find that there are significant differences pre and post-1982 with the establishment of the Court of Appeals for the Federal Circuit. I also find that there are significant differences in reactions for plaintiff patent-holders and defendant patent-holders. Interestingly, there is no similar effect for appellate court decisions relative to the district court. To my knowledge, this is the first study that measures the stock market reactions to legal outcomes of patent cases

The dynamics of patent citations

The use of patent citations as a measure of patent quality increased dramatically in recent years. I estimate the hazard of patent citation, and find evidence of unobserved heterogeneity. Hazard estimation provides a means to separate patent quality from citation inflation

Learning by suing: structural estimates of court errors in patent litigation

This paper presents structural estimates of the probability of validity, and the probability of Type I and Type II errors by courts in patent litigation. Patents are modeled as uncertain property rights, and implications of the model are tested using stock market reactions to patent litigation decisions. While court errors are inherently unobservable, the estimation quantifies beliefs about patent validity and court errors in a Bayesian context by relying on observable win rates and stock market reactions. I estimate that the underlying beliefs about validity average from 0.55 to 0.70 for litigated patents. For a number of different specifications, I show that Type I errors (finding a valid patent invalid) occur with an estimated probability of 0.20 to 0.25. The range for Type II errors (finding an invalid patent valid) varies more broadly, from near zero probability to as high as 0.40. Additional implications of the model address patent value

The Economics of a Centralized Judiciary: Uniformity, Forum Shopping and the Federal Circuit

In 1982, the US Congress established the Court of Appeals for the Federal Circuit (CAFC) as the sole appellate court for patent cases. Ostensibly, this court was created to eliminate inconsistencies in the application and interpretation of patent law across federal courts, and thereby mitigate the incentives of patentees and alleged infringers to "forum shop" for a preferred venue. We perform the first econometric study of the extent of non-uniformity and forum shopping in the pre-CAFC era and of the CAFC's impact on these phenomena. We find that in patentee-plaintiff cases the pre-CAFC era was indeed characterized by significant non-uniformity in patent validity rates across circuits and by forum shopping on the basis of validity rates. We find weak evidence that the CAFC has increased uniformity of validity rates and strong evidence that forum shopping on the basis of validity rates ceased several years prior to the CAFC's establishment. In patentee-defendant cases, we find that validity rates are lower on average, but do not find either significant non-uniformity of validity rates across circuits or significant forum shopping.

Patent protection, creative destruction, and generic entry in pharmaceuticals: Evidence from patent and pricing data

This paper merges patent citation data with data on pharmaceutical patent expirations, generic entry, and pricing to explore the effects of observable patent characteristics on off-patent and on-patnet pharmaceutical pricing. Using a sample of drug patents facing generic entry in the 1990s, I find that the price of branded drugs increased on average in the face of generic entry. Importantly, I find that the number of patent citations that a drug receives from other firms is correlated with a decrease in markup and a decrease in the duration of the markup. Conversely, self-citations are correlated with higher prices and slower decay in prices. The results indicate that patent citations may signal the degree of inter-molecule substitution. And, importantly, self-citations may indicate a degree of cumulative patenting that enables a firm to effectively extend or strengthen the original patent protection. This research takes a step forward in understanding the distinction between “positive” citations and “negative” citations related to creative destruction.