Re C (Adult: Refusal of Treatment) 
A client with chronic mental disease sought injunction to prevent the amputation of his gangrenous foot without his written consent.
Judgment by Thorpe J: The question to be decided is whether it has been established his capacity is so reduced by his chronic mental illness that he does not sufficiently understand the nature, purpose and effect of the amputation. Although his general capacity is impaired by his mental disease, it has not been established that he does not sufficiently understand the nature, purpose, and effect of the treatment he refuses. Indeed, I am satisfied that he has understood and retained the relevant information, that in his own way he believes it, and that in the same fashion he has arrived at a clear choice.
There are three stages in assessing the capacity:
1. take in and retain the information;
2. believe the information; and
3. weight and balance the risks and needs.
Lesson to Learn
Do not assume the client is mentally incapacitated by his/her chronic mental disease. Mental capacity needs to be assessed on every occasion. A client with chronic mental disease can make mentally sound judgment.