Robert Cunningham, Sr., was employed as a security guard for Shelton Security Service, Inc. (Shelton) (defendant) and assigned to patrol the Little Barn Deli and Market. In the early morning hours of his shift, Cunningham asked three young men to leave the store because they were attempting to shoplift. The parties exchanged words and yelled back and forth. As the young men exited the store they said they would come back and kill Cunningham. A short time later, Cunningham went outside the store because he was not feeling well. After a few minutes, a night clerk went outside to check on Cunningham who was unconscious in his car. Cunningham had died from sudden cardiac arrest. Cunningham’s son, Robert Cunningham, Jr., filed suit as administrator of his father’s estate (the Estate) (plaintiff) against Shelton for workers’ compensation benefits. At trial, the night clerk on duty the night Cunningham died testified that incidents like the one that occurred between Cunningham and the young men typically happened on a weekly basis except that Cunningham had not been threatened before. At the close of the evidence, the trial court granted Shelton’s motion to dismiss the complaint because the emotional stress experienced by Cunningham during his last shift was not extraordinary or unusual in comparison to the stress he ordinarily experience on the job. The Estate appealed. The Special Workers’ Compensation Appeals Panel disagreed and found there was sufficient evidence of causation to warrant a trial and reversed the trial court’s dismissal. Shelton filed a motion for full court review of the Panel’s decision. The Tennessee Supreme Court granted Shelton’s motion for review to consider whether the trial court erred in dismissing the Estate’s suit.