This year's Supreme Court confirmation hearings included much talk about the importance of legal precedent—but recent Supreme Court opinions have cited fewer precedents than those written during the 1950s, according to a new study. Analyzing opinions written from the late eighteenth century to the present, two political scientists find that the average number of citations rose throughout the nineteenth and early twentieth centuries, as the principle of stare decisis, or letting previous decisions stand, became widely accepted and the number of cases available for citation increased. Under Chief Justice Earl Warren the trend reversed, with the average number of citations in an opinion plummeting from about fifteen in 1953 to about five in 1969—a phenomenon, the authors note, in keeping with the popular perception of the Warren Court as activist or even revolutionary. Over subsequent years, as the Court gradually became more conservative, the average number of citations per opinion rose; by the early 1990s it stood at just over twenty. By the end of that decade, however, it had begun to fall again (the study does not speculate as to why), and in 2000 it was down to about seven—not much more than during the Warren era.

—"The Authority of Supreme Court Precedent: A Network Analysis," James H. Fowler and Sangick Jeon, University of California at Davis