For the next couple of weeks, we’ll be taking a brief time off from our look at the Court’s oral arguments in order to look at an issue we’re studying over on California Supreme Court Review – what can be inferred from the average time a case remains pending at the Court, from the allowing of the petition for leave to appeal to the oral argument to the decision?

In California, the time from grant of review to oral argument is most of the total lag time for a case, because the Court is required (with limited exceptions) to decide cases within ninety days of oral argument. Our task is made a bit more complicated in Illinois because unlike in California, the appellate dockets are not online. So to calculate the time from grant to argument, we reviewed all of the “Leave to Appeal Dispositions” archived on the Court’s website (this was also the source of our posts called “True Reversal Rates,” calculating the percentage of cases for each district for which PLAs were filed which were not only heard on the merits, but reversed). On the civil side, our data includes 224 data points from allowance of the PLA to argument, and 239 data points from argument to decision. (The difference arises from the fact that I haven’t yet figured out where on the court’s site the opening date for a direct appeal – the date analogous to the grant of the PLA – can be determined.)

We report the data for civil cases between 2010 and 2016 in Table 443. The average wait from the allowance of the petition for leave to appeal and the oral argument is 190.6689 days – just slightly over six months. The average lag time from oral argument to decision in civil cases during these years has been 137.8833 days. So when your petition for leave to appeal is allowed in a civil case at the Court, you can expect to get a decision, on average, in ten to eleven months. There’s not an enormous amount of variability in these numbers. The standard deviation for the grant-to-argument number is 67.62, meaning that 68% of the cases have fallen between 123 and 257 days. The standard deviation for the argument-to-decision number is, interestingly, half-again as big – 95.24824. This suggests that 68% of the argument-to-decision lag times in civil cases have fallen between 42 days and 232 days. So the time your case will take to come to argument is a good bit more predictable than the time the Court will take to decide the case.

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