Capacity
Whether a person is mentally capable of performing a juristic act is ultimately a legal, rather than a medical, decision. Neville J expressed this particularly robustly when he said(1)

(1) Richmond v Richmond (1914) 111 LT 273, at 274, per neville J.

Although the court attaches a great deal of weight to the evidence of a registered medical practitioner, it does not prefer medical opinion to lay opinion.

Capacity
Chapter 3 Page 45
See MCA 2005 ss 2-3
MCACode of Practice (Chapter 4)
Especillay 4.14; 4.16
Page 46: the presumption of continuance is not supported by MCA 2005

Onus on the person alleging, capacity or incapacity to make particular decision at the time the decision needs to be made. Standard of proof is the balance of probabilities
Page 72
Page 81
Page 382
Page 363
If the donor wants to restrict the power to when he cannot make decision because he lacks capacity to make the decision, the donor should be advised that financial institutions might ask for evidence of incapacity on each occasion.
Elderly Clients, (Denzil Lush . . .) ISBN 978 1 84661 173 5

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