Causation is the required nexus between a negligent act and medical evidence of injury in TBI litigation, and it is often seen as the weakest link by the defense. This is because, unlike an injury diagnosis, an injury cause is unobservable, and can only be inferred based on the expert interpretation of the circumstances surrounding an injury. Thus, the defense approach is to minimize the risk of TBI from a traumatic event, commonly using non-medical (i.e., engineering) experts to cast doubt on causation by citing to an injury “threshold” that was not reached by the event, or using medical experts to claim that injuries pre-existed the event. The plaintiff’s burden is to prove causation “but-for” the traumatic event, and thus the approach requires a balanced risk assessment, comparing the risk of injury from the trauma, to the risk of injury at the same point in time, but if the trauma had not occurred. The concept is incorporated into a “3-step causation” methodology that is outlined in the 10th DCA Etherton decision, which is based on a 2009 publication by Dr. Freeman (i.e., Plausibility, Temporality, Lack of More Likely Explanation). He will explain how the approach is reliably applied to TBI litigation to not just demonstrate, but to quantify “more likely than not” probability of causation in a variety of case types.