This article originally appeared in the July 2013 Product Liability Committee newsletter.
A CRUCIAL ISSUE in the successful defense of a product liability case is the exclusion of other incidents and accidents involving products of the manufacturer. In old school parlance, prior incidents were often referred to as "other similar incidents" or "OSI," a term which should be avoided because it presupposes similarity which does not necessarily exist. The specter of other incidents, if not addressed consistently and aggressively throughout the course of the litigation, can transform an otherwise defensible case into a problematic one.
The primary defense tool for excluding other incident evidence is the "substantial similarity" standard. While the concept of "substantial similarity" is not novel, this article surveys recent case law from various jurisdictions which reinforce this important evidentiary standard. (1) When effectively applied, the "substantial similarity" test serves as a potent legal basis to resist and limit discovery, to exclude opposing experts, to support motions in limine, and to substantiate exclusion of evidence and even dismissal of claims at trial. Left unchallenged, evidence of other incidents has the real potential to distract the fact finder from proper legal determinations by injecting unrelated and prejudicial facts and allegations of defect which have not withstood proper evidentiary scrutiny. The following summary provides current case law to buttress the assault on other incident evidence.
In Graves v. CAS Medical Systems, (2) the South Carolina Supreme Court applied the substantial similarity test in affirming the exclusion of three expert witnesses under South Carolina's expert evidence standard. Graves is instructive in this regard because it demonstrates that the substantial similarity rule can be invoked not only to exclude other incident evidence itself but also to challenge expert testimony that relies on such evidence.
Six month-old India Graves died while being monitored by a CAS Medical System product. (3) Her parents, Kareem and Tara Graves, filed a product liability lawsuit against CAS, alleging that "the monitor was defectively designed and failed to alert them when India's heart rate and breathing slowed." (4) India Graves was a triplet, born premature, and that condition required her hospitalization for 6 weeks. When she was released, the treating physician, as a precaution, instructed the Graves to use the CAS product to monitor the infant's breathing and heart rates. The product included a loud alarm that would sound if the infant were to stop breathing or have any major fluctuations in heart rate. (5) The product incorporated many intricate features and redundant safety measures, including a backup alarm along with a recording system that kept a log of alarm soundings. India died in her sleep while she was hooked up to the system, but, according to the Graves, the alarm never sounded. (6) Contrary to that allegation, the product's recording system reported that the alarm did sound. (7)
The Graves' claims centered on a software design defect theory involving "spaghetti code," defined as a condition when computer code becomes unstructured and creates "a rather tangled mess." (8) Three experts were utilized to support the Graves' theory, initially identifying three potential causes: hardware error, software error, and complaint error. (9) All three experts opined that software error was deemed the most probable cause after the possibilities of hardware and complaint error were ruled out by them. (10) CAS moved to exclude all three experts, contending that their testimony was not reliable because each relied on reports of other alleged failures to support their conclusion that software error was the cause. (11) The trial court excluded the three experts and granted summary judgment.
The Graves court began its exclusion analysis by acknowledging that an expert, in certain circumstances, can base his conclusion on a form of differential diagnosis--that is, by "eliminating the likely causes until the most probable one is isolated. …