A new law review article uses citation analysis to get a measure of the influence of state supreme courts. Jake Dear & Edward W. Jessen, “Followed Rates” and Leading State Cases, 1940-2005, 41 U.C. Davis L. Rev. 683 (2007).
The California Supreme Court has been seen as an influential court, both in studies and anecdotally. The authors sought to explore that claim, updating and refining the earlier studies. (Mr. Dear is the Chief Supervising Attorney for the California Supreme Court and Mr. Jessen is the Reporter of Decisions.)
With the help of LexisNexis (the owner of Shepard's Citations), they developed a database of cases that had not only been cited by other state courts but followed. Not surprisingly, California was consistently at the top of the list -- most cases that have been followed at least once, most cases that have been followed at least 3 times, most cases followed since 1986, etc.
A new result was that the Washington State Supreme Court was consistently in the number two slot. Older studies had placed New York, New Jersey, or other states higher, but with this data it was Washington. See note 87 of the article for a list of the six Washington cases that have been followed six times or more.
The authors say that the various state supreme courts typically have around the same number of full opinions. A difference, though, is the pool.
California’s highest court certainly has a large and rich inventory of cases from which to select — the court considers approximately 5400 petitions for review and 3000 requests for original writs annually....Id. at 703. Washington, a much smaller state (both in area and population), had 1,576 cases in its pipeline, for which it selected for review and wrote full opinions in 124. Washington Courts, Supreme Court: Court Activity by Source of Review.
It's an interesting piece of work. The fact that our state shows up in all the graphs is an extra hook for readers from Washington.
Update (March 4): See Calif. up, N.Y. down in study gauging influence, Nat'l L.J., March 3, 2008. (I can't link to this article free.)