The South Dakota Supreme Court issued a mixed ruling in *Hamer v. Duffy*, partially affirming and partially reversing a circuit court decision in an automobile accident case that raises important questions about employer liability under the doctrine of respondeat superior.
The case stems from an automobile accident on April 8, 2019, involving Justin Hamer and Paul Duffy. At the time of the collision, Duffy was acting within the scope and course of his employment with Cornerstone Poured Foundations, Inc. Justin Hamer and his wife Kim filed suit against both Duffy and Cornerstone, alleging that Duffy was negligent in causing the accident and that Cornerstone should be held liable for Duffy's actions under respondeat superior doctrine.
The doctrine of respondeat superior holds employers liable for the negligent acts of their employees when those acts occur within the scope of employment. This legal principle is designed to ensure that businesses bear responsibility for harm caused by their workers while performing job-related duties.
Cornerstone denied that Duffy was negligent and raised the defense of contributory negligence, arguing that Hamer's own actions contributed to the accident. This defense, if successful, could reduce or eliminate the defendants' liability depending on South Dakota's comparative fault laws.
The case encountered significant procedural complications before trial. The circuit court, presided over by Judge John R. Pekas in Lincoln County's Second Judicial Circuit, granted Cornerstone's motion to exclude testimony from two of Hamer's expert witnesses. The court determined that their testimony would not be helpful to the jury, dealing a blow to the plaintiffs' case preparation.
Just two weeks before trial was scheduled to begin on December 6, 2022, Hamer moved to amend his complaint on November 22, 2022. This last-minute amendment request, occurring so close to trial, likely created additional legal and procedural issues for all parties involved.
The case was argued before the South Dakota Supreme Court on August 27, 2025, with the opinion filed on February 4, 2026. The high court's decision, designated as case number 30776 and cited as 2026 S.D. 4, represents the latest development in what has been a lengthy legal proceeding spanning several years.
Justice Devaney authored the opinion for the court, though the specific reasoning behind the partial affirmance and partial reversal is not detailed in the available court documents. The mixed nature of the ruling suggests that the supreme court found merit in some aspects of both parties' arguments while rejecting others.
The plaintiffs were represented by a team of attorneys including Danny R. Ellis of Truck Wreck Justice, PLLC, based in Chattanooga, Tennessee, and Scott G. Hoy and James L. Hoy of Hoy Trial Lawyers, Prof. LLC, from Sioux Falls, South Dakota. The defendants were represented by Mark J. Arndt and Tyler A. Bradley of Evans, Haigh & Arndt, LLP, also based in Sioux Falls.
The involvement of out-of-state counsel suggests the complexity and potential significance of the case, particularly regarding the expert witness issues that arose during pre-trial proceedings. Expert testimony often plays a crucial role in automobile accident cases, helping juries understand technical aspects of vehicle dynamics, accident reconstruction, and injury causation.
While the specific details of the supreme court's reasoning are not available from the current documentation, the case appears to involve fundamental questions about the scope of employment doctrine and its application in motor vehicle accident cases. These issues are particularly relevant for businesses that require employees to drive as part of their job duties.
The case also highlights the procedural challenges that can arise in complex litigation, including disputes over expert witness testimony and last-minute attempts to amend complaints. These procedural issues can significantly impact the outcome of cases and demonstrate the importance of thorough case preparation and strategic legal planning.
For businesses in South Dakota, this case may provide important guidance on when employers can be held liable for accidents involving their employees. The mixed ruling suggests that the application of respondeat superior doctrine may depend heavily on the specific facts and circumstances of each case.
The decision also may have implications for how courts handle expert witness challenges and pre-trial procedural issues in similar cases. The exclusion of expert witness testimony can significantly impact a plaintiff's ability to prove their case, particularly in complex accident scenarios requiring technical analysis.
As this case demonstrates, automobile accident litigation involving employee liability can be particularly complex, requiring careful consideration of employment law principles, tort liability standards, and procedural requirements. The South Dakota Supreme Court's mixed ruling reflects the nuanced nature of these legal determinations and the importance of thorough factual and legal analysis in reaching appropriate conclusions.