Does a Person with a Medical Condition Affecting His Mind Have the Mental Capacity to Make a Will?


One of the grounds for challenging the validity of a Will is that the person who made the Will did not have the mental capacity to understand his actions.  With an aging population and higher rates of medical conditions, such as Dementia and Alzheimer’s Disease, which may affect a person’s memory and other mental functions, questions about testamentary capacity arise more frequently.

In a recent case Bull Estate v. Bull, the Supreme Court of BC provided further guidance on the issue of testamentary capacity. In Bull Estate, the deceased made a Will in 2010 leaving more assets to her daughter than her son. The deceased died in September 2012. Her son challenged the Will on the basis that, amongst other things, the deceased’s progressive dementia made her incapable of making the Will.

The Court found that the deceased had the requisite testamentary capacity when she executed the Will in 2010, and the Court further stated that sufficient mental capacity to make a Will may exist despite the presence of cognitive deterioration, and a will-maker may have sufficient mental capacity even if his/her ability to manage other aspects of his/her affairs is impaired.

In reaching its conclusion, the Court summarized the following non-exhaustive principles that have been established by courts over the years:

  • the test for testamentary capacity is not overly onerous;
  • simply having an imperfect or impaired memory does not in of itself absent testamentary capacity unless it is so great as to leave no disposing memory;
  • the will-maker needs to have an appreciation of the claims of the persons who are natural objects of his/her estate and the extent of his/her property of which he/she is disposing;
  • because testamentary capacity is a legal question and not a medical question, a medical opinion, although valuable and relevant, is not determinative of testamentary capacity;
  • a will-maker cannot be found not to have testamentary capacity simply because he/she chose to leave his/her estate in a manner that some might think unkind.

While each case of testamentary capacity turns on its own unique facts and evidence presented, the Bull Estate decision sets a high bar for a person challenging a Will to establish that the will-maker did not have the requisite mental capacity to make the Will, even if the will-maker suffered from medical conditions affecting his or her mental functions when the Will was made.