Patent scope is a fundamental dimension of the patent system. Because scope is so foundational, scholars have worked for decades to build an extensive and well-developed theoretical literature on the topic. There is, however, a glaring absence of empirical work on patent scope. This article conducts the first empirical assessment of how patent owners enforce the scope of their patents. Specifically, this article exploits a feature of patent procedure that requires plaintiffs to state whether they are asserting a narrow segment of their patent (dependent claims) or the broadest portions of their patent (independent claims) in litigation. The results are counterintuitive, particularly with respect to nonpracticing entities (“NPEs,” known colloquially as patent trolls). NPEs are thought to litigate aggressively and indiscriminately—pushing the boundaries of their patents and suing every likely defendant falling even arguably within the scope of the patent.
