concurring.
I agree with the reasoning and result of the majority opinion, but write separately to emphasize, in my view, the burden of proof that will contestants must carry.
We are bound by, and follow, the pronouncement of our supreme court that a party contesting a will because of a testator’s alleged insane delusion has the burden to prove the existence and effect of such delusion by a preponderance of the evidence. In re Estate of Smith, 53 Ariz. 505, 508-09, 91 P.2d 254, 255 (1939). Generally, this requires that “the trier of fact find the existence of the contested fact to be more probable than not.” In re Juvenile Action No. J-84984, 138 Ariz. 282, 283, 674 P.2d 836, 837 (1983). Put more simply, a preponderance is usually determined by the “greater weight of all evidence” presented. Black’s Law Dictionary 1182 (6th ed. 1990).
In Smith, however, and in In re Estate of Greene, 40 Ariz. 274, 281, 11 P.2d 947, 949 (1932), the only other Arizona case which discusses insane delusions, our- supreme court indicated that a preponderance may be somewhat different in this context. In Smith, the court said that a will would not be set aside unless it “clearly appears” that the testator did not understand the disposition. 53 Ariz. at 509, 91 P.2d at 255. From Greene, we learn that, not only must the alleged delusion be false, but it must be “utterly unfounded” and “unwarranted” from the circumstances. 40 Ariz. at 281, 11 P.2d at 949.
Other states impose similar rules. For instance, both Oregon and Michigan apply a preponderance test to testamentary capacity; see Lacey v. Meindl, 216 Or. 373, 339 P.2d 447, 448 (1959); Gardnier v. Smith, 198 *569Mich. 203,164 N.W. 382, 383 (1917); yet both recognize that a will should be upheld unless it is clearly the product of the testator’s insane delusion.
In Oregon, an insane delusion must have “absolutely no foundation in fact, and even slight evidence which provides a basis for the [testator’s] belief negates the existence of a delusion.” Dillon v. Phillips, 92 Or.App. 65, 756 P.2d 1278, 1279 (1988). In Dillon, the testator disinherited his children because he believed that they had lied to and stolen from him. Although his beliefs were wrong, “there were events which could have provided a basis for them” in that the children had been raised by their grandmother and the testator’s contacts with them were “infrequent and were best characterized by fighting and mutual abuse.” Id. The will challenge, therefore, was denied. Id.
Similarly, the Michigan Court of Appeals has held: “[T]here must be a great deal of proof that the suspicions or belief of a testator are completely unfounded before they can be held to be an insane delusion.”
... We need only determine whether there was any evidence presented upon which the testator could have based his belief, however arbitrary it might appear to this Court. If there is any evidence, however slight or inconclusive, which might have a tendency to create the testator’s belief ... then we must conclude that the belief was not an insane delusion.
Karris v. Frustaglio, 148 Mich.App. 171, 384 N.W.2d 119, 122 (1986) (emphasis added and citation omitted); see also In re Estate of Raney, 247 Kan. 359, 799 P.2d 986, 993 (1990); Huffman v. Dawkins, 273 Ark. 520, 622 S.W.2d 159,162 (1981)-.
Accordingly, when deciding whether a will is the product of the testator’s insane delusion, preponderance requires more than a mere weighing of the evidence. It requires a court to give controlling weight to any supportable justification that the testator may have had to hold the belief that he or she did. Any other rule would make a will contest too attractive an option for disappointed relatives.
In the instant case, I agree with the majority’s result for two reasons. First, there is no evidence in the record to suggest a reasonable basis for Killen’s beliefs that Russel, R.C., and Carolyn were in the mafia, lived in her attic and sprayed chemicals and parasites in her home, cut her arms and hands with glass, or tried to kill her or take her property. Second, the expert testimony in this case is extraordinarily probative. Dr. Patel examined Killen almost contemporaneously with her execution of the will and found her to have a delusional paranoid disorder. Dr. Don examined her twenty-one months later and made the same diagnosis. Significantly, neither of these psychiatrists were procured by the contesting parties for the purpose of obtaining testimony. In short, the record contains no supportable justification for Killen’s beliefs.