At least since the seminal work of the (US) National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research in the 1970s, a fundamental distinction between research and practice has underwritten both conceptual work in research ethics and regulations governing research involving human subjects. Notwithstanding its undoubted historical importance, I believe the distinction is problematic because it misrepresents clinical inquiry. In this essay, I aim to clarify the character of clinical inquiry by identifying crucial contextual constraints on justification constitutive of clinical science. This analysis shows that, from an epistemological point of view, clinical research and clinical practice are not sharply distinct but intimately intertwined. This result is important in its own right-an enriched understanding of the epistemology of clinical research is valuable in and of itself. But this result is also important because it has profound implications for the ethics of human subjects research.