Anatomical Gift Directive, Validity
Anatomical gifts may be made by a donor's will, as well as any other document that has been properly executed.  Proper execution requires the donor to sign the document in the presence of two witnesses, who must also sign the document. All three people must actually observe each of the others write his or her signature to the document.

A donor who is physically unable to write his or her own signature may have another person execute the document on his or her behalf. Two witnesses are also required to observe this entire process and sign in the same manner as above.

Also note that an Anatomical Gift Directive that makes a gift of the donor's entire body is not valid unless it has been properly executed at least 15 days prior to the donor's death.

See: Anatomical Gift Directive, Who May Create; Anatomical Gift Directive, When Effective; Signing By Another Person; Gift of the Entire Body