Citation Analysis of Canadian Case Law

This study uses simple statistical and functional analysis in conjunction with network analysis algorithms to examine the network of Canadian caselaw using data supplied by the Canadian Legal Information Institute (CanLII). Seeking to explore three basic questions, the study describes the database coverage of CanLII along with that of two commercial vendors and juxtaposes that information with the number of citations to cases decided by courts within each province each year. The study then uses analysis of time-series network rankings for each case to determine 1) the age at which cases in the network typically cease to be important, and 2) what characteristics define those cases that continue to be important despite the passage of time. The analysis reveals that indegree centrality and PageRank scores of caselaw within the network are effective predictors of the frequency with which those cases will be viewed on CanLII's website. Further, statistical and functional analysis of network rankings of each case over time suggest that cases typically cease to be cited in 3 to 15 years, depending on the jurisdiction, with the exception of Supreme Court of Canada decisions, which persist for 50 years. The study concludes that roughly 19% of Canada Supreme Court cases remain important despite the passage of time, whereas in all other jurisdiction, less than 3% of cases continue to be cited regularly over time.