When you cross-examine an expert’s report, you are at a considerable disadvantage if you focus on the report and overlook the validity of the tools and procedures used to create that report.
Assessments in Psychology and Psychiatry are all based on X means Y. X consists of your client’s responses to the assessment questions or tasks and Y consists of the meanings attributed to those responses. The attributed meanings that constitute Y are often at the heart of the expert’s report and can significantly influence the judicial decision.
As the cross-examining attorney for the defendant, your questions to the expert should be designed to assess if the measures used meet the criteria for psychometric and construct validity. The following are examples of such questions:
“Dr. A., how can we know, in this case, that X actually means Y?”
“When you say, Dr. A., that the measures you used are commonly used in psychological assessments, does frequent use make them valid?”
“Dr. A., do the assessment measures that you employed have psychometric validity and could you please explain for the court what constitutes psychometric validity.”
“Dr. B., it appears that the conclusions and recommendations in your report are based on your interviews with my client. Can you please tell the court how we can know that your interview questions and the conclusions and recommendations derived from them are valid?”
“Dr. B., would you please explain for the court what construct validity means and what role it played in your assessment of my client?”
Dr. C., you had my client complete the Personality Assessment Inventory (PAI) which you state has psychometrically valid clinical scales. You also state that my client’s responses to the items on the PAI were such that none of the clinical scales indicate a problem. Is this correct? (Yes). “Yet, Dr. C., you devote considerable time to the Diagnostic Considerations segment of your computer-generated PAI report in that you repeatedly make reference to the possibility that my client exhibits symptoms of a personality disorder. Dr. C., is it true that whereas the clinical scales of the PAI have psychometric validity, the computer-generated Diagnostic Considerations component of the PAI does not and could not have such validity because it consists of speculative considerations which, in the case of my client whose clinical scales are normal, is clearly damning?
As the attorney for the plaintiff, you need to make certain at the outset that your expert can correctly answer the types of questions illustrated above.
When conducting assessments, Dr. Cochrane uses the psychometrically valid Minnesota Multiphasic Personality Inventory (MMPI-2). When providing consultations on the reports of other health professionals, Dr. Cochrane reviews the psychometric validity of the assessment measures used, the construct validity of the interview methods used and the appropriateness of the conclusions and recommendations derived from these procedures.
Dr. Cochrane also provides helpful guidance for developing cross-examination questions in all realms of law-related psychology.
Psychology & The Law