Unlike other legal documents, a will generally isn’t valid unless two adult witnesses watch the will-maker sign it. The witnesses must know that the document is intended to be that person’s will, and they must also sign the document themselves.
(For a more general overview of the requirements for a valid will, see How To Determine if a Will is Valid.)
Why this extra level of formality and caution, when it’s not required for other important documents such as contracts or promissory notes? The simple answer is that by the time a will takes effect, the person who signed it is no longer around to say whether or not the document that’s being presented to the probate court is really his or her will. But if there are witnesses, they can come to court and testify that the will-maker stated the document was his or her will, and appeared to be of sound mind and not under any undue influence.
When you’re talking about a will, a notarized signature is not the same thing as a witnessed signature. Only two states, Colorado and North Dakota, currently allows will-makers to have a signature notarized instead of witnessed.
Not everyone can be a witness to a will. The requirements vary from state to state, but here are the basic rules:
Each witness must be a legal adult, which usually means 18 or over.
Most states require that witnesses be "disinterested"—in other words, that they not stand to inherit under the terms of the will. A beneficiary’s spouse may also be disqualified from serving as a witness. If a beneficiary does serve as a witness, the will’s gift to that person could be declared void by a court. The rest of the will would remain in effect.
It’s usually not a problem for the lawyer who drew up a will to also serve as a witness when the will is signed, even if he or she is named as the executor and will profit later from charging fees for the executor’s work.
Every state requires that a certain procedure must be followed when a will is signed. Here’s the typical procedure:
In some states, the witnesses don’t have to be in the same room when they sign the will. In others, they don’t even have to watch the will-maker sign, as long as the person later tells the witnesses that he or she signed the document. Or they may be allowed to watch the will-maker sign the will, and sign it later themselves.
The witnesses must know that the document is a will, or the document won’t be valid. In one case, the brother of an elderly man asked two men to "witness something," the man was about to sign, but didn’t know it was a will. When the will was later challenged in probate court, the judge threw it out.
In some states, certain unwitnessed wills can be valid. These states accept "holographic wills," which are wills that are written and signed entirely in the deceased person’s handwriting. Some states require that they be dated as well.