New Mexico (plaintiff) charged William Mark Mann (defendant) with intentional child abuse resulting in death. The victim was impaled with a screwdriver. At trial, Mann produced a medical expert who testified the impalement could have been accidental. One juror, an engineer, used engineering calculations to check the expert's testimony. The juror calculated the chances of accidental impalement at less than 1 in 20 million and shared that information with other jurors. Jurors also shared observations based on their own experiences with children and medical experts. The jury convicted Mann. Mann appealed to the New Mexico Supreme Court on the grounds that the engineer introduced new evidence that was not subject to cross examination, thereby tainting the jury's verdict.