The random]ized clinical trial is widely accepted as the optimal approach to evaluating the safety and efficacy of medical treatments. Resistance to randomized treatment assignment arises regularly, most commonly in situations where the disease is life-threatening and treatments are either unavailable or unsatisfactory. Historical control designs, in which all participants receive the experimental treatment with results compared to a prior cohort, are advocated by some as more ethical in such circumstances; however, such studies are often highly biased in favor of (...) the new treatment and frequently yield misleading results. Alternative controlled designs motivated by the desire to maximize the number of patients with the treatment ultimately determined to be superior have been proposed, but have been challenged on both methodological and ethical grounds. Debates about appropriate and ethical study designs recurred during the recent Ebola Virus Disease epidemic in West Africa. Despite its devastating nature, the EVD epidemic showed the ongoing necessity of conducting randomized trials to obtain convincing evidence of the safety and efficacy of therapeutic interventions. (shrink)