A physician who, to a reasonable degree of medical certainty, determines that the principal is capable or incapable of revoking a declaration or a physician or provider who administers or does not administer mental health treatment according to and in good faith reliance upon the decision or direction of the attorney-in-fact or the validity of a declaration is not subject to criminal prosecution, civil liability, or professional disciplinary action resulting from a subsequent finding of a declaration's invalidity.
755 ILCS 43/55