Clinical decision-making frameworks often treat decision-making capacity as a threshold question that determines whether authority remains with the patient or shifts toward a surrogate. That approach becomes ethically unstable when capacity fluctuates, support changes what a patient can understand or communicate, present wishes diverge from earlier commitments, or the consequences of a decision differ in reversibility. This conceptual and normative analysis develops a temporal account of longitudinal decision-making in which agency and authority are assessed across changing decisional states rather than fixed once for an entire episode of care. Drawing on contemporary work on supported decision-making, advance care planning, dementia, surrogate judgment, value change, reversibility, and institutional practice, the analysis distinguishes contemporaneous agency, supportability, prior commitments, and surrogate authority as related but non-equivalent sources of normative guidance. It argues that surrogate authority should ordinarily expand only to the degree required by the patient’s current decision-making limitations and should remain open to reassessment when those limitations, available supports, expressed wishes, or decision consequences change. Prior commitments retain substantial normative weight but do not automatically extinguish ethically meaningful present expression. A temporal approach therefore treats authority as revisable across longitudinal care while retaining safeguards for serious, irreversible, and legally constrained decisions.
