This article examines the application of the ought‐implies‐can principle in the legal domain, especially in the relationship between obligations and responsibility. It addresses the challenge of cases in which an agent cannot do what is required of her, and yet it seems plausible to say that she has an obligation. To deal with these cases, two parallel distinctions are made: between rules of conduct and rules of imputation, and between doings and things done. It is proposed that these distinctions show (...) that the principle operates in two different but complementary ways: as part of prescriptive relations and as part of responsibility practices. (shrink)