89. (1) On an application (being an application that does not involve considerations relating to life-sustaining treatment) made to it by any interested party, the court may make a declaration as to whether—

(a) an advance healthcare directive is valid,

(b) an advance healthcare directive is applicable, or

(c) a designated healthcare representative is acting in accordance with the relevant powers.

(2) On an application (being an application that involves considerations relating to life-sustaining treatment) made to it by any interested party, the High Court may make a declaration as to whether—

(a) an advance healthcare directive is valid,

(b) an advance healthcare directive is applicable, or

(c) a designated healthcare representative is acting in accordance with the relevant powers.

(3) Whilst awaiting a decision of the High Court relating to an application under subsection (2), nothing in the advance healthcare directive concerned shall be construed to prevent a person from—

(a) providing life-sustaining treatment to the directive-maker, or

(b) doing any act which he or she reasonably believes to be necessary to prevent—

(i) a serious deterioration in the health of the directive-maker, or

(ii) if the directive-maker is a pregnant woman, a deleterious effect on F129[her pregnancy].