In Dillon v. King, one sister contested their father’s will and codicil and also asserted other claims against her sister. No. 05-20-00215-CV, 2022 Tex. App. LEXIS 2991 (Tex. App.—Dallas May 4, 2022, no pet. history). In 2010, the father executed a will leaving everything equally to his two daughters. Thereafter, he moved to Texas to be near the contestant. The contestant then accessed the father’s bank account. The father told Texas Adult Protective Services that he allowed her to use the account but that she no longer had access to it. Later, the father signed a new codicil, leaving everything to the applicant. After a bench trial, the trial judge admitted the will and codicil to probate and ordered the contestant to take nothing on her other claims. On appeal, the appellate court discussed many different issues.

The court described the standards for mental capacity and undue influence as follows:

The matters in question in this case are Culpepper’s testamentary capacity and whether he executed the codicil because of undue influence by King. A testator has testamentary capacity when he has sufficient mental ability to understand he is making a will, the effect of making a will, and the general nature and extent of his property. He must also know the natural objects of his bounty and the claims upon them, and he must have sufficient memory to collect in his mind the elements of the business transacted and hold them long enough to form a reasonable judgment about them. In a will contest, the pivotal issue is whether the testator had testamentary capacity on the day the will was executed, but evidence of the testator’s state of mind at other times can be used to prove his state of mind on the day the will was executed, provided that the evidence demonstrates that a condition affecting his testamentary capacity was persistent and likely present at the time the will was executed. To set a will aside because of undue influence, a contestant must prove (1) the existence and exertion of an influence (2) that subverted or overpowered the testator’s mind at the time he executed the instrument (3) so that the testator executed an instrument he would not otherwise have executed but for such influence.


The contestant challenged the introduction of expert evidence by the applicant on the basis that the expert was not qualified. The court of appeals affirmed:

To testify as an expert, a witness must be qualified “by knowledge, skill, experience, training, or education,” such that his or her testimony will assist the trier of fact. Tex. R. Evid. 702. This means that the expert must possess special knowledge as to the very matter on which the expert  proposes to give an opinion…

Dillon argues that Cassius was not qualified to testify about Culpepper’s capacity for several reasons. Cassius did not attend medical school or take any courses in medical science. At the time of trial, he did not have his Ph.D., was not a forensic psychologist, and did not practice forensic psychiatry. He did not regularly treat people with dementia. He did not know the meaning of all of the terms in Culpepper’s medical records, and he was unfamiliar with at least some of Culpepper’s medications.

The question before us is whether the trial judge acted unreasonably in concluding that Cassius possessed special knowledge on the subject on which he proposed to give an opinion—Culpepper’s mental abilities when he executed his will and codicil. We conclude that she did not. Cassius testified that he had five years of post-graduate education in forensic psychology and that he would receive his Ph.D. in the field “any minute now.” His Ph.D. thesis concerned testamentary-capacity proceedings. And he had previously done three forensic autopsies related to dementia. Given Cassius’s training and experience, we conclude that the trial judge did not abuse her discretion by concluding that Cassius met the minimum qualifications to be permitted to testify about Culpepper’s mental abilities when he executed the will and codicil.

Id. The court held that the expert’s testimony on the mini mental status exam was admissible:

First, Dillon argues that Cassius’s opinion that Culpepper possessed sufficient capacity to sign the codicil is unreliable because it was based in part on Cassius’s view of a Folstein Mini Mental Status Examination (MMSE) performed on Culpepper by his physician, Dr. Ahn. Cassius opined that an MMSE is lacking in some areas, such as “executive functioning,” and he elaborated that “[t]here is poor content validity to make an interpretation based on somebody’s executive functioning with the MMSE exam.” Dillon argues that Cassius’s view is unreliable because Dillon’s expert witness, Dr. Lisa Clayton, opined that Culpepper’s MMSE score, together with his MRI and EEG results, placed him in the moderate stage of dementia, during which he would have had “basically no executive functioning.” We disagree with Dillon’s argument. We see nothing in the record squarely contradicting Cassius’s view of MMSE results, much less establishing that his view is unreliable. Clayton herself testified that an MMSE result, in and of itself, is not enough to support a conclusion that someone has dementia, and she called the MMSE “kind of a rudimentary test.” As for Clayton’s conclusion that a person with moderate dementia would have basically no executive functioning, her testimony may conflict with Cassius’s, but conflicting expert testimony does not necessarily show that one expert’s opinion is unreliable.

Id. The court also held that the expert had sufficient foundational data to support his opinions: “opinions about a deceased person’s mental capacity can[] reliably be based on a combination of medical records and witness interviews…” Id.

The court also affirmed the admission of expert evidence regarding undue influence:

In Cassius’s expert report, which was admitted into evidence, Cassius said that the IDEAL model, developed by Dr. Bennett Blum, M.D., is one of the best-known models for assessing potential undue influence. The model recommends consideration of five factors in financial cases: (1) isolation from pertinent information, friends, relatives, or usual advisors; (2) dependence, whether physical, emotional, or informational; (3) emotional manipulation and/or exploitation of vulnerability; (4) acquiescence because of the first three factors; and (5) financial loss. Cassius considered the information he had about Culpepper in light of these factors in reaching his conclusion that it was unlikely that King had undue influence on Culpepper.

On appeal, Dillon argues that King did not support the validity of the IDEAL model with evidence of peer review or publication, that the model appears to rely heavily on subjective interpretation, that there was no evidence about the technique’s potential rate of error, and that there was less than a scintilla of evidence to show that the IDEAL model has been generally accepted as valid by relevant professionals. Moreover, Clayton testified that she was not familiar with the IDEAL model.

Dillon’s critique of the record support for the IDEAL model’s reliability has some force. However, assuming without deciding that the trial judge abused her discretion by admitting Cassius’s undue-influence opinion, we conclude that admission of this evidence did not probably cause the rendition of an improper judgment. A successful challenge to an evidentiary ruling usually requires the complaining party to show that the judgment turns on the particular evidence admitted or excluded. This determination requires review of the entire record. Here, the IDEAL model, as described by Cassius, amounted to little more than common sense—people who are isolated, dependent, and subjected to manipulation or exploitation are more susceptible to improper influence. And Cassius’s specific undue-influence conclusion in this case, which was based on witness descriptions of Culpepper, is unlikely to have swayed the trial judge more than the witness descriptions themselves did.


The court also affirmed the finding that the father had mental capacity to execute the codicil. The court relied on medical records, which mentioned dementia but stated that the father remained stable. The court reviewed the testimony of both parties’ experts, who had differing views of the father’s mental capacity. The court also reviewed law witness testimony, which showed that the father knew who he was and was able to communicate effectively with other and travel by himself around the time of the executed codicil. The court held that this evidence was sufficient to contradict the contestant’s expert testimony and was sufficient to support the trial court’s finding of capacity to execute the codicil.

The court also reviewed the father’s ability to execute a power of attorney document, naming the applicant. The court stated that the contestant had the burden of proof to prove that the father was not mentally competent and also held:

Documents executed by a person who lacks sufficient mental capacity may be avoided. To have mental capacity, a person must have sufficient mind and memory to understand the nature and effect of his act at the time of the document’s execution. Capacity may be assessed by considering factors such as (1) the person’s outward conduct, (2) preexisting external circumstances that tend to produce a special mental condition, and (3) the person’s mental condition before and after the relevant point in time, from which his mental capacity or incapacity may be inferred. Expert testimony of capacity to contract is not required because the requisite proof may reside within the common knowledge and experience of laypersons.

Dillon argues that there is no evidence or insufficient evidence that Culpepper had capacity to contract when he executed a power of attorney in February 2012 and a beneficiary-designation form in October 2012. Because Dillon bore the burden of proof on this capacity issue, she must show that she conclusively proved that Culpepper lacked capacity on those occasions or that the trial judge’s contrary finding was contrary to the great weight and preponderance of the evidence.

Dillon argues that the evidence conclusively or overwhelmingly supported her incapacity-to-contract defense because (1) her expert, Clayton, specifically testified that Culpepper lacked capacity to contract and (2) lay-witness testimony could not controvert Clayton’s opinion testimony. We disagree with Dillon’s argument. Even uncontroverted expert opinion testimony is not conclusive unless the subject is one for experts or skilled witnesses alone. Capacity to contract is not a subject for which expert testimony is required. Thus, Clayton’s testimony that Culpepper lacked capacity to contract was not conclusive evidence of that fact, and the trial judge was free to consider the entirety of the evidence and to reject Clayton’s opinions. Moreover, the lay testimony from Rockwell, King, and Roderick Dillon about Culpepper’s behavior during the relevant time frame is also relevant evidence the trial judge could consider and credit.6Link to the text of the note For example, although Clayton opined that Culpepper most probably lacked capacity to buy his house in 2011, Roderick Dillon testified that Culpepper’s decision to buy the house was “a logical, fine decision” and that no one brought up any capacity issues at that time. Additionally, there was evidence that in September 2012 Dillon told TAPS investigator Rockwell that Culpepper was not impaired even though he had dementia. In sum, we reject Dillon’s legal-sufficiency challenge because the evidence does not establish as matter of law that Culpepper lacked capacity to contract at the relevant times.