Yun-chien Chang and Geoffrey Miller

This paper investigates the decay of precedents in three unique databases: citations in all published opinions by state supreme courts from 2019 (102,555 citations); citations in all published opinions by state supreme courts from 2003 (114,777 citations); and citations by all state and federal courts to state supreme court opinions issued in 2003 (259,627 citations). We find that the frequency of citation drops off by a roughly constant ratio with each passing year. The large scale of our data and the extended period of time studied suggests that this pattern must be the result of underlying forces not having to do with particular circumstances of time or place. We also find, however, that although the general pattern is consistent across our data, there are significant differences in rates of decay: the precedential force of prior cases drops off more rapidly across different characteristics of both the citing and cited cases. We offer some conjectures about possible reasons for the observed differences in decay rates.