Which legal document names the person authorized to make health care decisions for an incapacitated patient?

The appropriate legal document that designates someone to make health care decisions on behalf of an incapacitated patient is the advance health care directive. This document often includes provisions for appointing a health care proxy or agent, who is given the authority to make medical decisions when the patient is unable to do so due to incapacitation.

In contrast, a last will and testament is primarily concerned with the distribution of a person's assets after their death and does not address health care decisions during a person's life. A living will specifies a person's wishes regarding medical treatment in scenarios where they are unable to communicate due to illness or injury, but it does not assign someone to make those decisions for them. The power of attorney can grant broader authority to an agent for various matters, including financial decisions, but it specifically needs to be a durable power of attorney for health care to cover medical decisions. Therefore, advance health care directives are specifically tailored for health care situations, making them the correct choice for this question.