An advance directive is also known as a living will form, and it is a document that specifies your wishes if you become mentally incapacitated or unable to communicate those wishes to your health-care provider yourself. In a living will form you can specify whether or not you want specific treatment or life support.

A living will is unlike a regular legal will because most courts will recognize and respect your wishes even if it is contrary to some people's interpretation of the current state/federal laws.
With that said, sometimes doctors will be sued for malpractice when he or she has been put into a situation where they must decide whether to treat a patient who may recover, or follow the wishes expressed in the patient's living will form.

As you may well know, there are always circumstances and events which we could never predict, especially where death is concerned. Where a family member or spouse has doubts about whether you would make the same decision now, knowing all the facts, can use that as their grounds to challenge the contents of a living will in court. If they're explanation is compelling enough, they have a good chance of convincing most courts.

Since there is no legally specified standard for living wills, you can't just go to the courthouse and buy a copy of one. You must seek out a living will form from a law firm, or website. Although you can find free living will forms they are usually fairly basic but are most likely good enough to provide a standard written declaration.

Even though there is no legal specific standard legislated, all living will forms have a fairly similar structure. These include:
1) the choice to prolong life
2) whether or not painkillers should be used as needed or used regardless of the consequences
3) the contact details of your personal doctor
4) whether or not you wish to donate any 1 or more of your organs and for what reason
5) you must include a declaration that it is your wish and right to refuse medical treatment and that you are well informed of what this means.
6) finally you must sign the form along with two witnesses