The purpose of a health care directive is to communicate your feelings about your own end-of-life care. With a health care directive, also known as a living will, you provide instructions about your end-of-life medical treatment in the event that you are unable to make decisions for yourself. It allows you to communicate your wishes regarding treatment to your medical decision-maker (also called a health care proxy), as designated in your medical durable power of attorney.

The health care directive is your statement on your own position about end-of-life decisions. By contrast, the medical durable power of attorney covers all aspects of medical incapacity; its purpose is specifically to grant decision-making power to those you choose.

A health care directive is often lengthy, and may not be relied upon by medical professionals in end-of-life situations; instead, the people designated in your health care directive and your medical durable power of attorney will help you and your doctor fill out a POLST form: a Physician's Orders on Life-Sustaining Treatment. Your health care directive and your POLST should be consistent, and both should name the same individuals as your substitute decision-makers.