In 2009, one of the greatest threats to patient safety in emergency medical services was identified as paramedics’ clinical decision making, which was attributed as a failure to follow care protocols. Obliged to deliver care within the prescribed boundaries of medical protocols, yet called upon to exercise great feats of expert-level decision making in austere, time-pressured conditions, paramedics may have found themselves in a double bind. Complicating this issue is a lack of understanding of how these medical protocols influence paramedics’ medical care. Through the application of a cognitive systems engineering framework known as decision-centered design, this study sheds light on the nature of paramedics’ decision making from a naturalistic standpoint and identifies how the design of medical protocols influence their use. Two surveys issued in 2016 to paramedics in Kansas demonstrated that tabular and text based formatting, as compared to algorithmic protocols, are easier to learn and achieved higher ratings of information clarity. Paramedics primarily use their protocols for referencing drug doses and studying to commit them to memory, and rarely reference them on a call for making treatment decisions with the exception of rare medical conditions, using prognostic scoring and risk stratification assessments, infrequently encountered medical devices, and pediatric patients. By way of cognitive task analysis of expert paramedics and evaluation of their personal cognitive artifacts, 15 decision requirements were identified to guide the design of medical protocols. Additionally, paramedics’ mental processes were mapped to macro cognitive processes and functions. Prototypes developed from these criteria affirmatively achieved their design intentions, and demonstrated superior levels of positive sentiment and usability in comparison to industry standards and current protocols. They also achieved the provision of greater autonomy, openness, options, and freedom for paramedics to meet their patients’ needs.