What legal concept applies when an EMT or EMS system is liable even without clear demonstration of how injury occurred?

The concept that applies in this scenario is Res Ipsa Loquitor. This legal doctrine allows a party to establish negligence through the mere occurrence of an accident that would not typically happen without someone's negligence being inferred. In situations involving emergency medical services, when a patient suffers an injury during treatment, and the nature of that injury suggests it would not normally occur without negligence, the burden shifts to the EMS provider to prove that they were not negligent.

This principle is particularly important in emergency medical contexts, where various factors may prevent specific evidence of negligence from being presented. By relying on the idea that the very occurrence of the incident implies negligence, courts can hold the EMT or EMS system responsible for the outcome even in the absence of direct evidence detailing the cause of the injury. Thus, Res Ipsa Loquitor serves as a critical tool for ensuring accountability in situations where the injured party may not be able to provide a detailed account of the negligence that led to their injury.