The Federal Circuit is a response to a failure in judicial administration that produced a fractured, unworkable patent law; one that Congress concluded ill-served entrepreneurship and innovation. The purpose of the response – vesting exclusive jurisdiction for patent appeals in the Federal Circuit – was to permit that court to develop patent law in the direction of greater clarity and uniformity. Both at the time of the Federal Circuit’s creation and more recently, scholars, judges, and practitioners have waged great debates over whether patent law uniformity furthers the ultimate goals of entrepreneurship and innovation. These debates have rested on a largely untested empirical proposition: that the Federal Circuit’s patent law jurisprudence embodies a move towards doctrinal uniformity. This paper reports an empirical study that examines patent law uniformity through the measure of open decisional disagreement between Federal Circuit judges. Its central empirical observation is a remarkable increase in decisional disagreement – indicative of a decline in doctrinal uniformity – among Federal Circuit judges over the past several years. The paper raises and discusses several possible explanations for its surprising observations, including, inter alia, the Supreme Court and personnel changes at the Federal Circuit. It also considers what the observations and explanations might contribute to a current debate over the merits of Congress’s decision to unify patent jurisdiction in the Federal Circuit.