The ethical standards that regulate clinical research have multiple rationales. Among them is the need to protect potential subjects from making imprudent decisions, which extends beyond the soft paternalistic concern to protect people from making uninformed decisions to participate in trials. This article argues that a plausible risk/benefit restriction on clinical trials is presumptively justified by hard paternalism, which in turn is supported by a deeper fairness‐based rationale. This presumptive case for hard paternalism in research is not defeated by the alleged right to participate in clinical trials, by concerns about insult or status, by the need to conduct early phase trials that promise little to no benefit to participants, or by the recognition that some potential subjects are altruistically motivated.