If you disinherit your child because of a delusion that she is possessed by a demon, your will is going to be invalid. But what happens if you disinherit your child for no apparent reason and also happen to suffer from a delusion that you can communicate with household objects by touching them?

Are delusions that are not connected with the dispositive provisions of a will enough evidence of testamentary incapacity to invalidate the will?

The lengthy reasons in Laszlo v. Lawton, a 2013 British Columbia decision by Justice Ballance, suggest that this may not even be the right question to ask. Historically, delusions have often been seen as distinct issue from cognitive defects (memory and understanding) in applying the legal standard for testamentary capacity. In Laszlo, the court drew a hard link between them.

The British Columbia Supreme Court in this case does a service to lawyers and litigants by treating the leading testamentary capacity authority, the 1870 case of Banks v. Goodfellow, which is often given a perfunctory reference or quotation, to a fresh review. Significant leading decisions from the Supreme Court of Canada dating back a century are reviewed, as well as other cases from across Canada. This case is well worth a read for its comprehensive and clear refresher on the law of testamentary capacity alone.

However, the decision not only lays out the groundwork, but also builds up some of its interesting features. Most prominently among these is the effect of delusions on testamentary capacity.

It has long been settled law that a will is invalid if its dispositive provisions are based on the testator’s delusions. It has not always been clear that delusions that are independent of and do not vitiate the dispositive provisions of the will have the effect of invalidating the will absent other capacity-impairing factors. Laszo undertakes to answer that question.

In this case, the deceased suffered from “non-vitiating” delusions. She believed that she could communicate telepathically with objects by touching them; that characters on television were communicating with her; and that unidentified individuals had stolen significant amounts of money from her, among other irrational beliefs. However, these delusions were not obviously connected to her decision to disinherit her husband’s family who, on the evidence, were her previously-named beneficiaries and deserving of her generosity.

There was evidence that the deceased was still possessed of her cognitive faculties – that is, her ability to reason and remember – at the time she made her will in spite of the delusions (although it should be noted that there was also some evidence that she was confused and forgetful at times).

The court was left with an apparent dilemma. On the one hand, the deceased suffered from inexplicable and irrational beliefs that had only emerged in recent years; and the will was a significant departure from the previous will, cut out family members who would be expected to benefit, and made irrational bequests to two charities that the deceased and her husband had no affiliation with. On the other hand, there was some evidence that the deceased did not suffer from significant cognitive defects when she made her will and there is an apparent rule of law that non-vitiating delusions alone do not invalidate a will.

The court reconciled these opposing factors by accepting the evidence of an expert who explained that the onset of a delusional disorder, “often heralds an unrecognized and, therefore, untreated somatic illness, impacting brain function or degeneration of the brain itself.” Justice Ballance explained that:

It follows that the existence of delusions, while not themselves sufficient to defeat testamentary capacity, ought not to be excluded from consideration under the rubric of suspicious circumstances or the ultimate assessment of whether a testator possessed testamentary capacity at the material time. Non-vitiating delusions may reflect the ravages upon the testator’s mental functioning at large exacted by dementia or other brain disease, which cannot reasonably be ignored in the overall assessment of testamentary capacity.

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In my view, consideration of non-vitiating delusions in this broader sense where the evidence suggests that all or some of the testator’s delusions accompany a progressive degenerative brain disease like Alzheimer’s does not run afoul of the rule in Banks or its lineage.

It remains to be seen whether the weight of scientific authority continues to support this opinion and whether other courts adopt this method of examining delusions as a feature of mental function at large, but it does seem to fit tidily into the legal analysis under Banks v. Goodfellow.

Two other discussions in this case are worth noting. The court made some interesting observations about the use of MMSE results on the law of capacity. The deceased had twice been given a Mini-Mental State Examination (MMSE) around the time she made her will. She scored very well both times; i.e. the test showed no or minimal cognitive impairment. The court gave little weight to the test results, saying that the ubiquitous MMSE is a blunt tool, which has a limited ability to detect frontal lobe dysfunction or deficits in executive functioning, which are common in Alzheimer’s disease. Without more evidence of its reliability, it is impossible to determine the relative importance of its role in determining testamentary capacity.

The court also made interesting observations on the fluidity of capacity. As a generality, in the elderly, capacity will often emerge and worsen over time. However, capacity in any given case is not static. It can fluctuate slightly or wildly. There may be periods of incapacity interspersed with periods of lucidity. Appearances can be deceiving since a person who seems rational may not have capacity and a person who seems compromised may be capable. A diagnosis of dementia is not equivalent to a finding of testamentary incapacity; testamentary capacity is a legal concept rather than a medical one and both medical and lay evidence feature importantly.

This is a particularly long decision with extensive detail and elaborate reasons, but it is worth the read both as a primer and for its interesting insights into the role of delusions and other aspects of the law of testamentary capacity.