83. (1) The purpose of this Part is to—

(a) enable persons to be treated according to their will and preferences, and

(b) provide healthcare professionals with information about persons in relation to their treatment choices.

(2) A relevant person who has attained the age of 18 years and who has capacity is entitled to refuse treatment for any reason (including a reason based on his or her religious beliefs) notwithstanding that the refusal—

(a) appears to be an unwise decision,

(b) appears not to be based on sound medical principles, or

(c) may result in his or her death.