The New Hampshire Supreme Court recently affirmed a decision to exclude from evidence an expert’s opinion that exposure to lead paint caused neurological deficits in Somali children. The decision illustrates the difficulty that experts face when they apply a recognized methodology to a unique fact situation.

Facts of the Case

A group of children in New Hampshire who are Somali Bantu refugees sued the owners of apartment buildings in which they lived during 2005-06. They alleged that the apartments are contaminated by lead paint. They seek damages for adverse health conditions caused by lead poisoning that they attribute to living in the contaminated apartments.

It is apparently undisputed that the children have elevated levels of lead in their blood. To prove that they suffer from injuries caused by lead poisoning, the attorneys for the children intended to rely upon the testimony of Peter Isquith, a psychologist. After evaluating the 20 children, Isquith opined that 17 suffer from neurological deficits that were probably caused by lead exposure.

The defendants filed a motion to exclude Isquith’s expert opinion. After holding a six-day evidentiary hearing, the trial court granted that motion on the ground that Isquith’s opinions were not based on reliable principles and methods in light of the facts of the case. The plaintiffs were allowed to appeal that ruling before the case proceeded to trial. The New Hampshire Supreme Court issued its decision issued on August 23, 2016.

Expert Opinion Admissibility in New Hampshire

New Hampshire has adopted a Daubert standard for the admissibility of expert testimony. A New Hampshire statute allows a court to admit expert evidence only if the court finds that:

• the testimony is based upon sufficient facts or data;
• the testimony is the product of reliable principles and methods; and
• the witness has applied the principles and methods reliably to the facts of the case.

The New Hampshire Supreme Court has interpreted the statute to mean that there must be “good grounds” to believe the expert’s opinion is reliable before it will be submitted for a jury’s consideration.

The Expert’s Methodology

Isquith relied on two tests to help him decide whether the children suffered from neurological deficits. The first was the Reynolds Intellectual Assessment Scales (RAIS), an intelligence test that is considered appropriate for ages 3 to 94. The second was the Developmental Neuropsychological Assessment, Second Edition (NEPSY-II), which is specifically designed for children.

Both tests have been standardized, meaning that raw scores on the tests have been obtained from large populations. That permits the development of standardized scores that reflect the subject’s test result as compared to others who took the test. For example, if a particular score indicates that the subject scored in the 25th percentile, 75 percent of test-takers have achieved a better score.

The problem for Isquith was that the tests have been standardized with American populations. The groups that took the tests for standardization purposes did not include recent immigrants. Individuals who spoke English as a second language were expressly excluded from the standardization groups. That raised the question whether the tests were valid when applied to Somali Bantu refugees who were not native speakers of English.

Isquith attempted to compensate for the standardization problem by interpreting the test results cautiously. He tried to err on the side of finding no neurological deficit by looking for patterns of poor scores on all of the subtests (including nonverbal subtests) and by relying only on test scores that were well below the norm. He did not, however, compare the test results to a control group of Somali refugees who had not been exposed to lead paint.

The Trial Court’s Ruling

The trial court concluded that Isquith did not employ a reliable methodology because he used tests that had not been validated with regard to a Somali population, or any population that speaks English as a second language. The tests have a known error rate for an English-speaking population, but they have no known error rate for other populations. The court was concerned that poor test results might reflect the fact that the test-takers did not speak English as a native language, rather than reflecting cognitive difficulties.

If Isquith had administered the tests to a large group of healthy Somali refugees and used those results for a baseline comparison, he might have been able to produce valid results. While Isquith testified that he considered a Somali test subject to exhibit neurological difficulties if the subject scored below a certain cutoff level (identified sometimes as 10{d61575bddc780c1d4ab39ab904bf25755f3b8d1434703a303cf443ba00f43fa4} and other times as 15{d61575bddc780c1d4ab39ab904bf25755f3b8d1434703a303cf443ba00f43fa4}), he had no way of knowing whether significant numbers of healthy Somali refugees of similar age and circumstances would have scored above that cutoff level. His approach may have been “cautious” but, in the court’s judgment, it still amounted to “well-educated guesswork.”

The court also expressed concern that Isquith failed to account for other risk factors that may have depressed the test-takers’ scores. Their lack of preventative healthcare before arriving in the United States, their exposure to war, their low socioeconomic status, and other factors may explain their poor test scores. Since Isquith could not rule out those possibilities, the court decided that his methodology was unreliable.

Decision on Appeal

On appeal, the attorneys for the refugees argued that the trial court erred by imposing a stricter standard than whether Isquith had “good grounds” for his opinion. They contended that Isquith employed sound principles that were consistent with cross-cultural assessments made by clinical practitioners and school psychologists. The plaintiffs’ attorneys therefore asked the state supreme court to rule that the trial court exceeded its “gatekeeper” function and invaded the province of the jury by deciding that Isquith’s opinions were not well founded.

As is common when an appellate court reviews a decision concerning the admissibility of evidence, the New Hampshire Supreme Court applied a deferential standard of review. Evidentiary decisions are usually affirmed if the trial court applied the correct legal standard in a reasonable way, even if a different trial judge might have decided the admissibility issue differently.

In the absence of studies or other evidence that validated the results of tests administered to a population of Somali refugees, the supreme court decided that it was reasonable for the trial judge to conclude that Isquith lacked a scientific basis for concluding that the tested refugees suffered from neurological deficits. It was also reasonable to conclude that his opinions were not merely questionable, but were so unreliable that they should not be presented to the jury.

The case illustrates the difficulty that experts face when they apply a well-established methodology to a unique fact situation. It may not have been feasible for Isquith to conduct a validation study of the two tests on a healthy population of recent Somali refugees, but the court’s decision suggests that only evidence of that nature will prove that the plaintiffs suffered from neurological deficits due to lead poisoning. That is an unfortunate result for the children if they are lead poisoning victims, because the court’s decision will prevent them from being compensated for their devastating injuries.