Clinical equipoise

Clinical equipoise, also known as the principle of equipoise, provides the ethical basis for medical research involving randomly assigning patients to different treatment arms. Unlike uncertainty principle that relies on individual belief of researcher, clinical equipoise explicitly states that there must "exists . . . an honest, professional disagreement among expert clinicians about the preferred treatment"[1]. Even if the clinician personally prefers one arm over the other, randomization is still ethically sound when there are other responsible and competent clinicans who believe the other way around.

Sources and References
[1] Freedman B. Equipoise and the ethics of clinical research. N Engl J Med 1987; 317: 141-145.