Exclusion of Neuropsychology Expert Testimony Affirmed by New Hampshire Supreme Court

Expert witness was challenged on the type of tests used to assess neuropsychological deficits after plaintiffs were exposed to lead paint.

Facts:  This case (Osman v. Lin – Supreme Court of New Hampshire – August 23rd, 2016) is an appeal from a trial court opinion.  The plaintiffs are Somali Bantu refugees or whose parents are Somali Bantu refugees.  They sued the owners of the apartments in which they lived from 2005-2006 for exposure to lead paint.  In order to prove their case, the plaintiffs hired Peter Isquith (neuropsychology expert witness) to opine whether the plaintiffs had any neurological deficits that were more likely than not caused by the lead paint exposure.  The trial court excluded Isquith’s testimony was not the product of reliable principles and methods.  The case was then appealed to the Supreme Court.

Discussion: Isquith used two assessment tools to form his conclusions: 1) The Reynolds Intellectual Assessment Scales (RAIS) and 2) The Developmental Neuropsychological Assessment, Second Edition (NEPSY-II).  The NEPSY-II is a flexible battery of 32 subtests, each of which has been individually standardized and scored.  The defendants expert explained to the court that for many test applications, one looks for a “normative” group, which is a representative group of “normal” individuals.

One issue that Dr. Isquith faced in this cases was that the RIAS and NEPSY-II and other neuropsychological instruments were not developed or validated for use with the plaintiff population.  In fact, the normative sample for the NEPSY-II excluded children for which English is not the primary language.  Dr. Isquith knew of this issue and thus interpreted the test scores with caution.  His interpretation of the scores were such that he erred on the side of not finding a deficit, making it more likely that identifying any deficit was correct.

The defendants challenged Isquith’s testimony stating that the tests used were not suitable for evaluating Somali Bantu refugees and that the way he administered the tests and interpreted the results was unreliable.  The trial court agreed, stating that the plaintiffs failed to prove that 1) Isquith’s testimony was the product of reliable methodology and 2) Isquith reliably applied the methods to the facts of the case.

The main issue that the trial court had with Isquith’s methodology was that he was using tests that were not developed or validated for use in the Somali Bantu population.  Thus, Isquith would have difficulty figuring out how a normal Somali Bantu child would perform on the tests.  In addition, Isquith’s methodology was not subject to publication of peer review.

The Supreme Court reviewed the trial court’s finding that Isquith did not apply his methodology to the facts of the case.  The plaintiffs argue that he did use sound principles and methodology, stating that he used the same methodology used in school and clinical settings for cross cultural assessments.  The court disagreed, stating that although the RIAS and NEPSY-II are used  generally, they are not used specifically for the purpose of this case.

In addition, the plaintiffs have not referred to any articles or publications were these tests were specifically used on  Somali Bantu refugees.

Conclusion:  The New Hampshire Supreme Court affirmed the opinion of the trial court, stating that the lower court did exercise proper discretion when dealing with this expert.