Living wills are documents that give instructions regarding treatment if the individual becomes terminally ill or is in a persistent vegetative state and is unable to communicate his or her own instructions. The living will states under what conditions life-sustaining treatment should be terminated. If an individual would like to avoid life-sustaining treatment when it would be hopeless, he or she needs to draw up a living will. Like a health care proxy, a living will takes effect only upon a person's incapacity. Also, a living will is not set in stone; an individual can always revoke it at a later date if he or she wishes to do so.
A living will, however, is not necessarily a substitute for a health care proxy or broader medical directive. It simply dictates the withdrawal of life support in instances of terminal illness, coma or a vegetative state.
Also, do not confuse a living will with a "do not resuscitate" order (DNR). A DNR says that if you are having a medical emergency such as a heart attack or stroke, medical professionals may not try to revive you. This is very different from a living will, which only goes into effect if you are in a vegetative state. Everyone can benefit from a living will while DNRs are only for very elderly and/or frail patients for whom it wouldn't make sense to administer CPR.
For more information on end-of-life decision-making from the Mayo Clinic, click here.