Power, defined as the asymmetric control of valued resources, affects most human interactions.
Yet there is little observational evidence on how power affects real-world behavior and resource
allocation. We examine this question using the power differential in the doctor-patient encounter:
while it favors the physician in the clinical setting, powerful patients may be able to reduce this
asymmetry and influence physician behavior. We exploit the quasi-exogenous assignment of 1.5
million patients to physicians in US military emergency departments, using the difference in their
military ranks to measure their power differential. We find that power confers nontrivial advantage
to its possessor: “high-power” patients (those who outrank their physician) receive greater physician
effort and have better outcomes than equivalently-ranked “low-power” patients. Furthermore,
within-physician effort is higher for patients recently promoted than those about to be promoted.
We document negative spillovers from a physician’s high-power patients to their concurrently seen
low-power patients, as well as predictable interactions of such power dynamics with doctor-patient
concordance on race and sex. While power-driven variation in behavior is often undesirable, it is
especially concerning in healthcare where it can harm society’s most vulnerable patients.