The plaintiff has the burden to prove each element of a negligence claim arising out of lead paint exposure. In many cases, the plaintiff in a Maryland personal injury case will have an expert testify to assist the jury in understanding the evidence or determining a fact at issue. In a July 31, 2018 lead paint case, the Court of Appeals of Maryland considered whether a medical study cited by an expert provided a sufficient factual basis for his testimony. The court also addressed whether an expert could offer an opinion on specific causation by relying on medical study data along with an individualized analysis of the plaintiff’s injuries.The plaintiff in the case sued the owners of a residential property, alleging that his injuries, including mental and attention deficits, were caused by exposure to deteriorating lead paint at the property. At trial, the parties agreed that, due to the defendants’ negligence, the plaintiff was exposed to lead paint and that the exposure was the cause of the plaintiff’s elevated blood lead levels. The remaining questions for the jury were whether the lead exposure caused an injury to the plaintiff and, if so, the amount of damages. The jury returned a verdict in favor of the plaintiff and awarded approximately $1.3 million in damages. The defendants subsequently filed an appeal, arguing that the plaintiff had not sufficiently proven that his alleged injuries resulted in any damages. The plaintiff contended that the testimony of his expert witnesses satisfied his burden of proof.
In Maryland, an expert’s opinion must be based on facts that sufficiently indicate the use of reliable principles and methodology, which thus support the expert’s conclusions. The expert must also have a rational explanation for how the factual data led to the expert’s conclusion. On appeal, the court examined the medical studies used by the plaintiff’s experts. The first expert used medical studies that examined the relationship between ADHD and lead exposure. The court found that the studies indicated an association between the two, but not causation. This was significant, since it led the court to conclude that the expert’s testimony suffered from an analytical gap by overstating the known effects of lead exposure. Lacking a scientific basis, the expert’s testimony was therefore inadmissible.