The Growing Complexity of the United States Patent System

Abstract

In this Article, we compare a data set of 1000 U.S. patents issued between 1996 and 1998 to a similarly random sample of 1000 patents issued twenty years earlier, between 1976 and 1978. By studying the differences between the groups, we can get a clear picture of how the patent system has changed over time. The results are dramatic. By almost any measure - subject matter, time spent in prosecution, number of prior art references cited, number of claims, number of continuation applications filed, number of inventors - the patents issued in the late 1990s are more complex than those issued in the 1970s. While some of these effects are attributable to the patenting of new technologies like biotechnology and software, unknown in the early 1970s, the increase in complexity is robust even across areas of technology. Further, the patent system in the 1990s is more heterogeneous than it was in the 1970s. There are far greater differences by area of technology and by nationality in how patents are being prosecuted in the 1990s than there were in the 1970s. We explore a number of possible explanations for these results, and discuss the policy implications of the lack of uniformity that now characterizes our patent system.