Undisclosed Expert Rebuttal Testimony Exclusion Upheld by South Dakota Sup. Ct.

While South Dakota, like many states, does not require disclosure of rebuttal testimony, trial courts can require adequate proof as to what rebuttal testimony an expert witness would give, the South Dakota Supreme Court has ruled.

At two months old, N.W.O. was referred to Dr. Nanton, a pediatric gastroenterologist, who diagnosed N.W.O. with severe gastroesophageal reflux disease (GERD) and prescribed several medications, including Reglan, which can have adverse side effects.In O'Day v. Nanton 2017 S.D. 90, O'Day sued Steven Nanton, MD, for medical malpractice alleging he improperly treated the infant N.W.O. with the drug Reglan.

Over the course of 19 months, Nanton examined N.W.O. multiple times, performed a variety of tests, altered formula and food types. As Reglan use is recommended for a maximum of 12 weeks, Nanton attempted to wean N.W.O. off Reglan as his conditions improved, but N.W.O.'s vomiting would reappear and the Reglan dosage had to be reinstated. Nanton testified that he believed the benefits outweighed the risks in N.W.O.'s situation.

N.W.O.'s mother, Tracy McClure, testified that she began noticing problems with the infants development, including issues of standing, balancing, facial grimacing, uncoordinated jerky motions. After seeing a television commercial on the side effects of Reglan, McClure brought her concerns about the medication to N.W.O.'s primary care physician.

Nanton discussed with the primary care physician his attempts to wean the child off Reglan. After a subsequent exchange with McClure, Nanton informed the primary care physician to stop N.W.O.'s use of Reglan because of McClure's concerns. Nanton had no further involvement in N.W.O.'s care.

Two years later, O'Day and McClure filed a medical malpractice claim against Nanton, alleging breach of standard of care by treating N.W.O. with Regland causing N.W.O. injury. They retained Dr. John Sabow, a neurologist, who opined that by placing N.W.O. on Reglan, Nanton breached the standard of care and that, because of N.W.O.'s extended Reglan use and improper monitoring, N.W.O. had been poisoned by Reglan.

Nanton engaged Dr. Warren Bishop, also a pediatric gastroenterologist, who testified that Nanton's decision to use the drug was justified and appropriate, and that Reglan did not cause N.W.O.'s problems.

Nanton provided testimony from three other experts on causation, including Dr. Patrick Barnes, Medical Section Chief of Pediatric Neuroradiology at Stanford, who concluded in his testimony, based on N.W.O.'s pre-Reglan brain imaging by ultrasound and MRI, that his right and left cerebral hemispheres were asymmetric, and that his brain was underdeveloped early in the pregnancy, causing his developmental problems.

Another of Nanton's experts, Dr. Schaeffer, the Founding Director for the Division of Medical Genetics at the University of Arkansas, testified as well that N.W.O.'s MRI showed an abnormal brain at birth, and the abnormality was the cause of N.W.O.'s developmental delays. Nanton's third expert witness, Dr. Donald Chadwick, a pediatric neurologist, provided similar testimony.

O'Day and McClure's counsel then attempted to present rebuttal testimony from Sabow, stating that Sabow would rebut the conclusions made by Nanton's experts based on the MRI image testimony. Nanton objected to the untimely disclosure of Sabow's opinion, arguing that it would be prejudicial.

O'Day and McClure argued that they were unaware the MRI was going to be used as a basis for the opinions of Nanton's experts, and that Sabow's rebuttal testimony was not required to be disclosed.

The circuit court found that Sabow's rebuttal opinion would be “new and undisclosed”, excluding it. The court noted that O'Day and McClure had known that the MRI images would be part of the trial. The court did not speculate as to why Sabow failed to provide an initial opinion on the MRIs.

The jury returned a verdict in favor of Nanton. O'Day and McClure appealed, claiming in part that the circuit court erred in excluding Sabow's rebuttal testimony.

The South Dakota Supreme Court affirmed the circuit court decision. The Court found that as the jury had initially concluded via a special verdict form that Nanton was not negligent, it “never reached the issue of causation.”

Elaborating on the rebuttal issue, the state Supreme Court noted that no formal offer of proof as to the rebuttal testimony of Sabow was ever provided, only the testimony of counsel, stating: “Probably the least favored methods for an offer of proof is one of testimony by counsel because it carries the risk of failing to meet the standards of a good offer of proof — specificity and detail” and that the “sufficiency of an offer of proof before the trial court should be left to its discretion.”