(1) The principles set out in subsections (2) to (10) shall apply for the purposes of an intervention in respect of a relevant person, and the intervener shall give effect to those principles accordingly.

(2) It shall be presumed that a relevant person who falls within paragraph (a) of the definition of "relevant person" in section 2(1) has capacity in respect of the matter concerned unless the contrary is shown in accordance with the provisions of this Act.

(3) A relevant person who falls within paragraph (a) of the definition of "relevant person" in section 2(1) shall not be considered as unable to make a decision in respect of the matter concerned unless all practicable steps have been taken, without success, to help him or her to do so.

(4) A relevant person who falls within paragraph (a) of the definition of "relevant person" in section 2(1) shall not be considered as unable to make a decision in respect of the matter concerned merely by reason of making, having made, or being likely to make, an unwise decision.