24. Relevant and irrelevant considerations.

A discretionary power must be exercised for proper purposes which are consistent with the conferring statute1. The exercise of such a power will be quashed where, on a proper construction of the relevant statute, the decision-maker has failed to take account of relevant considerations or has taken into account irrelevant considerations2. In some statutes, some or all of the relevant considerations may be express3; where the statute is silent or the express considerations are not exhaustive, the courts will determine whether any particular consideration is relevant or irrelevant to the exercise of the discretion by reference to the implied