Expert Testimony by Police Officers: How is it Evaluated After Daubert and Kumho?

Jennifer Groscup, John Jay College of Criminal Justice
Steven Penrod, John Jay College of Criminal Justice

ABSTRACT
The admissibility of expert testimony has been a hot topic in the legal world over the last decade. Supreme Court cases, such as Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) and Kumho Tire Co. v. Carmichael (1999) modified the standard for the admissibility of expert testimony, which raised the question of how experts would be evaluated after these decisions. One type of expert evidence that is frequently presented to the courts is testimony by police officers. Appellate court cases discussing the admissibility of expert testimony provided by police officers were coded for content as part of a larger study on the overall effects of Daubert and Kumho on the admissibility of expert testimony, totaling over 300 experts. The most common topic of testimony given by police officers concerns the behavior of several types of criminals, particularly that of drug dealers. Preliminary analysis indicates that police officers were allowed to testify as experts in over 90% of the cases at the trial court level, and this admission rate was reduced to approximately 80% at the appellate court level. There were no changes in the admission of this type of testimony over time, at either the trial or the appellate court levels of these cases. However, these rates of admission are very high. Therefore, the judgment criteria used by appellate court judges in evaluating police officer testimony will be discussed and compared to other types of testimony frequently appealed in criminal trials. Implications for police officers serving as experts in the criminal justice system will be discussed.

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Updated 05/20/2006