A living will is a legal document that specifies how a person wishes to be treated in the event of terminal disease or life threatening physical injury. These instructions are followed when the person who made the living will is permanently incapacitated (in a coma or persistent vegetative state, for example). The will may outline which types of life extending treatments should or should not be used. Respirators, tube feeding, and resuscitation techniques are generally addressed in this document.

When a person is terminally ill but not incapacitated, his/her current wishes regarding medical care will be followed regardless of what the living will states. In the event of incapacitation without a terminal illness or injury, a health care power of attorney (POA) allows a third party such as a family member to make relevant medical decisions. A living will and POA are often drawn up at the same time to cover all eventualities. Family members and physicians should all be apprised of the details of a living will to reduce conflict over end of life care.