Decision-making capacity is commonly treated as a threshold question: can this person make this decision now? That inquiry is indispensable in many clinical and legal settings, but it can obscure a second normative problem—who should exercise decision authority when ability is partial, support-sensitive, temporally unstable, or distributed across relationships. This article develops an original relational framework for analysing that problem without displacing functional capacity assessment or converting relational autonomy into collective control. It distinguishes decision-making capacity from decision authority, then differentiates supported, shared, delegated, prospective, and proposed provisional forms of authority. The analysis argues that authority can remain patient-centred while being relationally enabled, temporally revisable, and constrained by safeguards against coercion, epistemic displacement, and premature substitution. Fluctuation introduces a further requirement: authority allocation should be assessed not only at a decision point but also against feasible support, timing, restoration, and reassessment. On this basis, the article proposes a Relational Decision-Authority Framework that organizes authority around retained agency, support conditions, interpersonal influence, temporal status, and the justification for any transfer or displacement. The framework is normative and analytic rather than a validated assessment instrument, legal rule, or clinical protocol. It is intended to make visible questions that binary capacity determinations may leave unresolved while preserving jurisdiction-specific law, the possibility of genuine incapacity, the independent moral importance of a person's present voice, and the need for empirical, conceptual, and cross-jurisdictional validation.
