In McDaniel v. Brown, the Supreme Court will review the use of DNA evidence in a 1994 trial for sexual assault and attempted murder. The Court granted certiorari to consider two procedural issues—the standard of federal postconviction review of a state jury verdict for sufficiency of the evidence, and the district court's decision to allow the prisoner to supplement the record of trials, appeals, and state postconviction proceedings with a geneticist's letter twelve years after the trial. The letter from Laurence Mueller, a professor at the University of California at Irvine, identified two obvious mistakes in the state's expert testimony.
This essay clarifies the nature and extent of the errors in this evidence in Brown. One might think that the expert's letter, the opinions of the lower courts, and the briefs—including one from "20 Scholars of Forensic Evidence"—would have done this, but there is more to be said.