This article addresses various factors involved in the tension that may arise between breach of confidentiality on the one hand, and dereliction of the duty to warn, on the other, in the context of medical law. Per illustration, examples from clinical psychiatric practice, in which the sharing of personal information is especially relevant, are featured. In sum, a practitioner must be reasonable in negotiating the proverbial tightrope: if he or she reveals too much, liability can arise, and, if he or she reveals too little, liability can arise. In medical law, the standard of reasonableness is measured with reference to “the reasonable practitioner”. Weighing up various factors (discussed herein), the reasonable practitioner takes confidentiality as the point of departure; only if there is a compelling reason to override confidentiality, will it afford legal justification to the practitioner