Legal Memorandum: Expert Testimony in a Products Liability Action

Issue: Under Massachusetts law, is expert testimony necessary in a products liability action to show the hazardous nature of a product?

In a products liability case, expert testimony that a product was or was not defective, dangerous or unreasonably dangerous is admissible even when that is the ultimate issue in the case.  Uloth v. City Tank Corp., 376 Mass. 874, 884, 384 N.E.2d 1188, 1194 (1978).  In fact, in design defect cases that involve technical or scientific issues that cannot be fully understood by the average juror without expert assistance, expert testimony about the defective nature of the product is an indispensable element of the plaintiff’s case, and the lack of such evidence may result in a directed verdict for the manufacturer.  See, e.g., Gynan v. Jeep Corp., 13 Mass. App. Ct. 504, 434 N.E.2d 688 (1982).  In other cases, however, the manufacturer’s breach of duty may be found by the jury’s evaluation of the evidence based on common knowledge, without the benefit of expert testimony on the issue.  See, e.g., Smith v. Ariens Co., 375 Mass. 620, 377 N.E.2d 954 (1978).

In the often-cited case of Smith v. Ariens Co., 375 Mass. 620, 377 N.E.2d 954 (1978), the defendant snowmobile manufacturer argued that the plaintiff had failed to present sufficient evidence to establish a breach of the defendant’s duty to design its snowmobiles so as to avoid unreasonable risks of injury in a collision, because the plaintiff did not introduce any expert testimony on the issue of whether the snowmobile was negligently designed.  Id. at 625, 377 N.E.2d at 957.  The […]