In response to public outrage stemming from exposés of animal abuse in research laboratories, the US Congress in 1985 mandated Institutional Animal Care and Use Committees (IACUCs) to oversee animal use at institutions receiving federal grants. IACUCs were enjoined to respect public concern about the treatment of animals in research, but they were not specifically instructed whether or not to perform ethical cost-benefit analyses of animal research protocols that IACUCs have chosen, with approval contingent upon a balancing of animal pain and suffering against a reasonable expectation of resultant human benefit. IACUCs have chosen not to make such ethical judgments but, rather, restrict themselves to an advisory role, often tweaking the details of animal-use protocols, but eventually approving all of them. This disinclination by IACUCs to take a broader ethical view of their authority and responsibilities may reflect a membership composition highly skewed towards animal researchers themselves (67%) and institutional veterinarians (15%), both with vested interests in continuing animal research. The resultant ethical monoculture may impair IACUC's ability to meet public concern for laboratory animal welfare. Psychological research has established that unconscious bias affects us all, that deliberations among the like-minded lead to adapting extremist positions, and that groupthink blinds organisations to alternatives that might be obvious to outsiders. Taken together, skewed IACUC membership composition and psychological research insights into unconscious bias and groupthink suggest that an infusion of ethical diversity by increasing the percentage of institutionally unaffiliated members on IACUCs would broaden their ethical perspectives and enable them to better address public concerns about laboratory animal welfare.