Living wills have been strongly endorsed in principle. Unfortunately, existing living wills are rarely used in clinical practice because they are vague and difficult to apply. To remedy this, we propose a new advance care document: the Medical Directive. The Medical Directive delineates four paradigmatic scenarios, defined by prognosis and disability of incompetent patients. In each scenario, patients are to indicate their preferences regarding specific life-sustaining interventions. The Medical Directive also provides for the designation of a proxy to make decisions in circumstances where the patient's preferences are uncertain. Finally, there is a section for a statement of wishes regarding organ donation. The Medical Directive provides an opportunity for significant improvement in the documentation of patients' preferences regarding life-sustaining care in states of incompetence. As an expression of a patient's wishes, the Medical Directive should be honored by courts and should facilitate physicianpatient discussions of critical and terminal care options.