What is the test for loss of testamentary capacity in an advanced age?

Precisely because persons of advanced years are not as “sharp” as they were when they were younger, the court must be very careful not to presume loss of testamentary capacity simply because they are more frail. Once testamentary capacity has been proven prima facie, as it is in this case, we turn to whether or not there are suspicious circumstances. However, we must not substitute mere suspicion for proof of suspicious circumstances. This principle is described rather aptly as follows: The eye may grow dim, the ear may lose its acute sense, and even the tongue may falter at names and objects it attempts to describe, yet the testamentary capacity be ample: Laramie v. Ferron, (1909) 1909 CanLII 50 (SCC), 41 S.C.R. 391 at page 409.