Last week, we addressed whether the lag time between oral argument and the Illinois Supreme Court’s decisions is an accurate predictor of dissent for the Court’s civil and criminal dockets. Today, we turn to a different question: the Supreme Court’s unanimity rate.
We report the Court’s rate of unanimous civil decisions in Table 255 below. The unanimity rate is remarkably stable throughout the sixteen-year period from 2000 to 2015. Although the rate was relatively low in 2000, with only 57.89% of the Court’s civil cases decided unanimously, the rate varied only five points in all between 2001 and 2004. In 2005, the unanimity rate jumped all the way to 84.78%, before falling to only 59.18% in 2006. Between 2007 and 2011, the unanimity rate was between 70 and 80% every year. Unanimity dropped sharply in 2012 and 2013 before returning to its trend rate in the most recent two years – 77.78% in 2014 and 79.55% in 2015.
To what degree have the Court’s occasional dips in its consistent 70-80% unanimity rate been lopsided decisions with only one dissenter? In Table 256 below, we report the “lopsided rate” – the percentage of the Court’s civil docket decided by the Court with zero or one dissenter. The rate varied in a narrow band between 2000 and 2004 – the 73.68% lopsided rate in 2000 suggests that several of the Court’s non-unanimous cases were decided with only one dissenter. The lopsided rate went all the way to 95.83% in 2005, dipping only slightly in 2006 before rising again to 90.24% in 2007 and 2009. For most of the years since, at least four fifths of the Court’s civil cases have been lopsided decisions, with zero or one dissenters. Most recently, 85.19% of the Court’s civil decisions in 2014 were lopsided, and 88.64% in 2015.
Join us back here tomorrow as we turn our attention to the Court’s criminal docket.