Assessment of decision-making capacity is a complex and important skill for emergency physicians. A clinician should be aware of the need to assess capacity in those who might have cognitive, mental, psychiatric, or organic impairments to capacity. The presence of any cognitive impairment does not negate the possibility of a patient having the decisional capability to properly consent to or refuse medical therapy in a given situation. Standardized tests have been developed that can help in the determination of decision-making capacity. When present, reversible organic medical conditions should be treated expeditiously, and decision-making capacity should then be reassessed. It may be advantageous to involve family members, social services, ethics consultants, or psychiatric consultants in challenging circumstances. When done appropriately, this process aims to allow a proper balance of patient autonomy and their best interest.