When a person has lost his mental capacity or the ability to communicate, he can no longer take any decision on whether to commence, continue or end his medical treatments. In order to meet such challenges or contingencies, in a legal document called ‘Living Will’ the maker of the same in advance indicates the mode and manner of his treatment in the event of his inability to stipulate such preferences in sick condition in future.
Wishes of the maker regarding his heath care preferences are documented in a Living Will, which everybody connected with his treatment are obliged to honor and respect in case due to illness or incapacity he is no longer in a position to decide on the same.
(More http://www.uslivingwillregistry.com/ )