Alcohol and Parasomnias: The Statistical Evaluation of the Parasomnia Defense in Sexual Assault,Where Alcohol is Involved

Sleep sex may be a defense for alleged sexual assault. The International Classification of Sleep Disorders (ICSD3) states: “Disorders of arousal should not be diagnosed in the presence of alcohol intoxication… The former [alcohol blackouts] are exponentially more prevalent.” A panel member of ICSD3, quoting ICSD3 asserts: “alcohol intoxication should rule out a sleep-walking defense”. This implies extremely strong support for a prosecution hypothesis (H_p) over a defense hypothesis (H_d). I use Bayesian methodology to evaluate the evidential probity of alcohol intoxication. The likelihood ratio, LR, measures the amplification of prior odds of guilt, . By Bayes' theorem, . I use data from cross-sectional studies of sexual assault and prevalence of alcohol use, in college students, with data from longitudinal studies, and data from the epidemiology of parasomnias to evaluate LR (alcohol). LR ~1.5 or 5, depending whether alcohol does, or does not, increase the risk of parasomnias. The proposition of extremely strong support for H_p implies a LR ~1,000,000, so the proposition in ICSD3 is not supported by formal analysis. The statistical reasoning in ICSD3 is unclear. There appears to be inversion of the Bayesian conditional (confusing intoxication given assault, and assault given intoxication) and failure to evaluate alcohol intoxication in H_d. Similar statistical errors in R. v Sally Clark are discussed. The American Academy of Sleep Medicine should review the statistical methodology in ICSD3.     

Latent fingermark visualisation using reduced-pressure sublimation of copper phthalocyanine

The sublimation of copper phthalocyanine (CuPc) at a temperature of 400°C under conditions of reduced pressure is shown to be an effective method of developing latent fingermarks on certain types of surface. Preliminary experiments on a limited selection of surfaces including paper, plastic and ceramic tiles were carried out using a simple apparatus consisting of a vacuum desiccator and a resistive heater. CuPc from the gas phase condenses preferentially on fingermark deposits, revealing deep blue patterns with excellent ridge detail clarity on light coloured surfaces. The technique is shown to be most effective on porous surfaces such as paper, but relatively ineffective on non-porous ceramic and plastic surfaces.     

Field reliability of competence to stand trial opinions: How often do evaluators agree, and what do judges decide when evaluators disagree?

Despite many studies that examine the reliability of competence to stand trial (CST) evaluations, few shed light on "field reliability," or agreement among forensic evaluators in routine practice. We reviewed 216 cases from Hawaii, which requires three separate evaluations from independent clinicians for each felony defendant referred for CST evaluation. Results revealed moderate agreement. In 71% of initial CST evaluations, all evaluators agreed about a defendant's competence or incompetence (kappa = .65). Agreement was somewhat lower (61%, kappa = .57) in re-evaluations of defendants who were originally found incompetent and sent for restoration services. We also examined the decisions judges made about a defendant's CST. When evaluators disagreed, judges tended to make decisions consistent with the majority opinion. But when judges disagreed with the majority opinion, they more often did so to find a defendant incompetent than competent, suggesting a generally conservative approach. Overall, results reveal moderate agreement among independent evaluators in routine practice. But we discuss the potential for standardized training and methodology to further improve the field reliability of CST evaluations.