Can a Person With Mild Cognitive Impairment or Alzheimer's Still Make a Valid Will in British Columbia?

This answer covers the law of British Columbia.

A diagnosis such as mild cognitive impairment or Alzheimer's does not by itself settle whether a will is valid. The question is whether the person was mentally capable of making the will. The Wills, Estates and Succession Act says a person aged 16 or older who is mentally capable may make a will. The statute does not define mental capability, and the test comes from case law that BC courts apply together with section 36.

How lucid intervals, medication and good days are weighed depends on the evidence in each case, and a lawyer can confirm how they might apply to your parent's situation. What the law does say is that if suspicious circumstances relate to mental capacity, the person relying on the will must establish capacity, and the standard is the balance of probabilities. Probate also checks that a will was made without fraud or undue influence.

Capacity is separate from the signing rules. A will must be in writing and signed in front of two or more witnesses present at the same time, and those witnesses must be 19 or older. A person who receives notice of a probate application can oppose the grant by filing a notice of dispute.