Making room for family involvement in medical decision-making

European-level legal norms place the competent adult patient at the centre of medical decision-making through free and informed consent, bodily integrity and self-determination, yet clinical decisions are often formed with the involvement of family members. This tension between individual legal authority and relational decision-making becomes particularly visible in culturally and linguistically diverse healthcare settings, where expectations concerning family roles, information disclosure and participation in decision-making may differ. In practice, excluding relatives may undermine communication, trust and culturally responsive care, while informal deference to family authority may compromise voluntariness, confidentiality and the patient's own wishes. This article asks how law can accommodate family involvement without allowing relatives to replace the patient as the legal source of consent or refusal. It rejects the familiar opposition between individual and relational autonomy and distinguishes instead between legal authorization and relational support. Drawing on Article 8 ECHR, the Oviedo Convention, national and comparative examples, and legal and support mechanisms, it identifies a lawful space for patient-led family participation. The proposed framework requires express and revisable patient authorization, private verification, documentation, confidentiality, voluntariness, equality-sensitive practice, and continuing patient control. Family involvement can therefore be accommodated without diluting consent, provided that relational support never becomes substitute authority.