In the past twenty years, several academic researchers have extended the study of amicus briefs to state courts of last resort. In 2001, Professors Paul Brace and Kellie Sims Butler published “New Perspectives for the Comparative Study of the Judiciary: The State Supreme Court Project,” 22 The Justice System Journal 3 (2001). They assembled data for amicus filings in all fifty state courts of last resort for all cases decided between the years 1990 and 2001. They concluded that in a total of nineteen states (Arkansas, South Dakota, Idaho, North Dakota, Iowa, Nebraska, Texas, Wyoming, Montana, Hawaii, Rhode Island, Arkansas, South Carolina, Maine, Nevada, Indiana, Virginia, West Virginia and North Carolina), less that 5% of their total cases resulted in amicus briefs. On the other hand, in five states (Oklahoma, Oregon, Michigan, New Jersey and California), 25% or more of all cases resulted in amicus briefs.
We begin our study of the Illinois data by replicating the same numbers year by year for the first half of our study period, 1990-2004. One caveat to our study before we begin. As I’ve pointed out before, since Illinois’ Supreme Court docket is not online and the coverage of amicus briefs in the commercial research vendors is incomplete, we must rely on the Supreme Court’s statement in the body of its opinions that certain amicus briefs were filed on each side.
In Table 1741, we plot the percentage of the Court’s civil cases each year that drew at least one amicus brief. The percentage started at 10.99% in 1990 before peaking at 21.82% in 1996. After a drop in the years immediately following that, it climbed steadily to 21.74% in 2003 and one-third in 2004. For the years 1990 through 2001, we’ve identified 104 of 1,515 total cases (civil and criminal) in which at least one amicus brief was filed – 6.86% of the total.
Next, we plot the yearly average number of amicus briefs filed for appellants in civil cases. Broadly speaking, the data follows the same pattern we found above – bottoming out in 1993 (0.0789) and 1994 (0.0667) and peaking in 1996 (0.2545) before rising back to 0.28 briefs per case in 2003 and 0.4444 in 2004.
Finally, we turn to the data for appellees. Appellee amicus briefs are substantially flatter: 0.099 per case in 1990, dropping all the way to 0.0267 in 1994, rising slightly in 1996 and 1997 before abruptly spiking in 2004 to 0.352 briefs per case.
The bottom line? Although our numbers differ somewhat from previous researchers, we agree about one thing – amicus briefs were comparatively rare in the Illinois Supreme Court during this era.