Psychological expert witness testimony and judicial decision making trends

Despite the establishment of the Daubert standard in 1993, the evidentiary criteria are rarely used as a basis for admissibility of expert witness testimony in the behavioral sciences. Ever since the promulgation of Frye and the Federal Rules of Evidence, controversy has surrounded the admissibility of expert testimony in courtrooms. There appears to be no existing uniform application of standards governing the admissibility of psychological expert witness testimony. Therefore, it is essential for the psycho-legal communities to explore judicial decision-making trends regarding psychological expert witness evidence. In this current research, psychological expert witness testimony and judicial decision-making will be explored. In preliminary examination, 97 criminal and civil case summaries from the LexisNexis Academic Database involved issues of admissibility. Analyses conducted by eight trained and paired coders revealed that reliability and assistance to the trier of fact were the most often cited reasons for admissibility in courts. Consistent with prior studies, it was also found that the most applied standards for admissibility of psychological evidence were the Federal Rules of Evidence. Interestingly, while the Daubert scientific criteria for admission of scientific testimony were mentioned, they were rarely utilized. A secondary analysis of 167 civil and criminal appellate cases indicated that the reliability of testimony (18% of all cases), ability to assist the trier of fact (17%), the expert witness' qualifications (17%), and the relevance of the testimony (16%) were the most commonly cited reasons for determining admissibility. A tertiary qualitative analysis focusing on these four categories then revealed eight major trends in admissibility of psychological expert evidence.