Advance directives are legal documents that allow individuals to express their healthcare preferences in advance of a time when they may be unable to communicate or make decisions. The legal authority derives from state law (each state has specific statutory requirements) and is supported by federal legislation including the Patient Self-Determination Act (PSDA, 1990), which requires healthcare facilities to inform patients of their rights to execute advance directives. Two primary types: (1) Living Will - a written declaration specifying desired and unwanted treatments in the event of terminal illness, persistent vegetative state, or end-stage condition. Limitations include ambiguous language, inability to anticipate every clinical scenario, and variation in state laws regarding triggering conditions. (2) Durable Power of Attorney for Healthcare (DPOA-HC) / Healthcare Proxy - designates a trusted individual to make medical decisions when the patient lacks capacity. The proxy uses substituted judgment (what the patient would have wanted) or, if patient wishes are unknown, the best interest standard. DPOA-HC is generally considered more valuable than a living will because the proxy can adapt to unanticipated situations and engage in...