The law regulates many aspects of decision-making around the withholding and withdrawing of life-sustaining medical treatment from adults who lack decision-making capacity and are approaching the end of their lives. For example, it governs whether an adult’s advance directive is binding and applicable and, if not, who is authorised to make the treatment decision and the criteria that should guide the decision. Doctors who treat patients at the end of life should be aware of the prevailing law so that they can practise within those legal parameters. However, the law in this field is complex and challenging for doctors to know and understand. Doctors will be prepared to invest time into learning about the law only if they believe that the law is worth knowing and that practising medicine in a legally compliant way is a desirable goal. This article provides insight into doctors’ attitudes about the role of law in medical practice in this field, and argues that education is required for doctors to reconceptualise knowledge of the law as constituting an integral component of their clinical expertise.