We offer the first comprehensive look at how a district judge’s experience affects decisionmaking in patent cases. We find that there is a strong, statistically significant relationship between a judge’s experience and case outcome: more experienced judges are less likely to rule for the patentee. Notably, the relationship exists only for rulings finding noninfringement; judicial experience has no relationship to the likelihood a judge will find a patent invalid. The relationship appears to hold across judges rather than to be driven by the rulings of particular judges. Beyond individual judges, some technologies (such as biotechnology and mechanics) are associated with more patentee wins, while patentees are less likely to win computer hardware and software cases. Some district courts, such as the District of Delaware and the District of New Jersey, are more likely to find patents infringed. By contrast, perhaps surprisingly, we find no significant relationship between litigation in the Eastern District of Texas and a judge’s ruling for or against the patentee. Finally, we find that suing on multiple patents is associated with an increased likelihood that at least one patent will be found to be infringed.

Our results challenge what has been an implicit assumption in the literature and discussion: that particular districts are biased in a particular direction, driving forum shopping. And they test for the first time the implicit assumption, made in the literature, in calls for specialized patent trial courts, and in the Patent Pilot Program, that experience with patent cases at the trial level will lead to different—usually assumed to be “better”—outcomes from what we see from generalist courts. Our results suggest that there is a difference, but that “better” may be in the eye of the beholder. They suggest some sort of learning effect among district court judges across the country and indicate that patentees benefit from litigating before inexperienced judges, at least on issues of infringement. Depending on the reason for this effect, adoption of a specialized patent trial court might help accused infringers but not patentees, raising broader questions about patent reform and how to measure the value of an expert court.