By creating a Living Will, a person who is of sound mind and is not incapacitated, declares their wishes in writing as to the medical procedures to be performed if they were to become terminally ill. With some exceptions, it should be remembered that a Living Will is generally only effective when a person is terminally ill and cannot communicate his/her wishes to a family or their physicians. A sample of a Living Will can be opened in another window to follow along through this discussion.
Unlike a will, which requires that a person die before it becomes effective, a Living Will is designed for the sole purpose to be effective before death. In fact, this document gives the health professionals the security they need to be able to honor your wishes, since they are extremely reluctant to even consider your wishes when you are suffering from a terminal illness. Hospitals and doctors would be subject to possible lawsuits if they were to make decisions for a terminally ill patient.
For example, they cannot simply disconnect life-support procedures because a terminally ill person tells them too. As incredible as it sounds, if the family does not wish these procedures to be disconnected, the hospital may decide the terminally ill person is not of sound mind enough for them to rely on the terminally ill person's wishes. The hospital or doctors do not want to be sued by the family for disconnecting a person's life-support and thereby, in effect, causing the "wrongful death" of that person. While the hospital may still ultimately win its case, it is much easier for the hospital to simply ignore the wishes of the terminally ill person, and take no action, thereby allowing them to remain on life-support systems for years in some cases.
While we can all be critical of our legal system, it is best to prepare for how it is working now, regardless of whether it is working well or poorly, and seek to change the system in the future where necessary. Regardless of your personal opinions, if a parent or child were to become mentally incapacitated right now, the hospital would likely not disconnect the support system in the absence of a clear expression of the incapacitated person's desires. So it is best to prevent the problem, and surprisingly, it is easy to do so, and to ensure your own wishes are upheld.
With a Living Will, you can decide the exact circumstances for disconnecting any life-support treatment. You can also specify who among your family or friends and doctors will have the power to decide when to make a decision to disconnect life-support systems.