Abstract
A standard of evidence is a rule or norm pertaining to the type or amount of evidence that is required to prove or support a conclusion. Standards of evidence play an important role in institutional review board (IRB) decision-making, but they are not mentioned in the federal research regulations. In this article, I examine IRB standards of evidence from a normative, epistemological perspective and argue that IRBs should rely on empirical evidence for making decisions, but that other sources of evidence, such as intuition, emotion, and rational reflection, can also play an important role in decision-making, because IRB decisions involve an ethical component which is not reducible to science. I also argue that an IRB should approve a study only if it has clear and convincing evidence that the study meets all the approval criteria and other relevant, ethical considerations; and that for studies which expose healthy volunteers to significant risks, an IRB should require that evidence be more than clear and convincing as a condition for approval. Additional empirical research is needed on how IRBs use evidence to make decisions and how standards of evidence influence IRB decision-making at the individual and group level.