Did the Michigan Supreme Court Appreciate the Implications of Adopting the “Disparity of the Risk” Measure of Minority Representation in Jury Pools in People v. Bryant?

Abstract

Due to an error in the computer program used by Kent County, Michigan, for about 15 months, the African-American proportion of jury pools was about one-half their proportion of the eligible population. Subsequently, a number of defendants appealed their convictions because the jury pool did not fairly represent the community. Although a Federal Court of Appeals found that the statistical evidence helped the defendant establish that African-Americans were under-represented; in a different case, People v. Bryant, the Michigan Supreme Court found the statistics insufficient. The different conclusions arose because the Michigan Court adopted a new criterion that the “disparity of the risk” measure should be at least 0.50. The statistical properties of the measure will be described and it will be seen that it is equivalent to requiring that the Kolmogorov–Smirnov distance between the two relevant distributions is at least 0.50. If one is comparing two normal distributions, with different means and the same variance, the requirement implies that the effect size would need to be at least 1.35 before one could conclude that they differed. Since effect sizes of 0.8 are considered “large,” the criteria used by the Michigan Court are far too stringent and if adopted nation-wide would allow individuals to have trials in front of juries where minorities are substantially under-represented.