The problem of standard‐of‐care in clinical research concerns the level of care that investigators ought to provide to research subjects in the control arm of their clinical trials. Commentators differ sharply on whether subjects in trials conducted in lower income countries should be provided with the same level of care as subjects in trials conducted in higher income countries. I consider an argument that commentators have employed on both sides of this debate: professional role arguments. These arguments claim to justify a conclusion to the standard‐of‐care problem solely by appeal to the professional obligations that investigators possess. I argue that prominent versions of professional role arguments cannot justify a solution to the problem of standard‐of‐care that is both determinate and reasonable simply by appeal to the professional obligations of investigators. Instead, to do so, one must also (1) determine the level of care or types of treatment that individuals are entitled to as a matter of distributive justice, and (2) identify which agents possess the duties that correspond to these entitlements. The level of care that investigators owe to subjects in the control arm of their clinical trials is thus in part dependent on the level of care that these subjects are entitled to as a matter of distributive justice, and whether it is the investigators who possess the corresponding distributive obligation to provide them with the care that they are entitled to.