(1) An advance healthcare directive is not valid if the directive-maker -

(a) did not make the directive voluntarily, or

(b) while he or she had capacity to do so, has done anything clearly inconsistent with the relevant decisions outlined in the directive.

(2) An advance healthcare directive is not applicable if -

(a) at the time in question the directive-maker still has capacity to give or refuse consent to the treatment in question,

(b) the treatment in question is not materially the same as the specific treatment set out in the directive that is requested or refused, or

(c) at the time in question the circumstances set out in the directive as to when the specific treatment is to be requested or refused, as the case may be, are absent or not materially the same.