For the past several weeks, we’ve been investigating what the data tells us about how the Illinois Supreme Court assembles its docket: whether the Court prefers final judgments; how often the Court takes up summary judgments; what counties and areas of the law have contributed most to the Court’s civil docket; whether a dissent at the Appellate Court helps in getting review (and if so, how much), and whether the Court reviews unpublished opinions.
We now turn to the centerpiece of our inquiry: the Court’s own decision-making process. First up: what can we infer from the amount of time the Court has had a particular case under submission?
Although the data for 2005 and earlier is incomplete, the Court’s lag time from oral argument to decision has remained relatively constant for at least the past ten years:
Not surprisingly, the Court’s lag time from oral argument to decision is a relatively strong predictor of whether or not the eventual decision will include dissenting opinions. Although lag times for unanimous decisions appear to be dropping in recent years, receiving a decision within four months after oral argument tends, more often than not, to indicate a unanimous Court:
Tomorrow, we’ll address the Court’s lag time from argument to decision when the Court is divided.
 The Court’s published opinions do not list the date of argument, and for the years 2000-2005, numerous Calls of the Docket are missing from the Court’s website. Accordingly, it is not always possible to determine when a particular case was argued.