Assessing decision-making capacity is a critical part of patient-centered care. The Miller & Marine algorithm helps clinicians evaluate whether a patient can communicate choices, understand consequences, apply personal values, reason logically, and maintain decision stability. Impairments from thought disorders, delirium, or depression may require deferring decisions to a surrogate or following an advanced directive. This structured approach ensures medical decisions respect the patient’s values and comprehension, rather than simply seeking agreement.