"The views of the majority in each of those cases is
consonant with the general principle that a public officer or
body upon whom or which is conferred a statutory discretion is
entitled to adopt general principles of policy relevant to the
manner in which the discretion is to be exercised in particular
cases, provided that such policy relates to matters which are
legally relevant to the exercise of the discretion. It might be
thought that generally it is desirable or even necessary for
there to be such a general policy to avoid any inconsistent,
arbitrary or capricious exercise of the discretion. The policy
must be lawful, ie. it must not require the discretion to be
exercised for extraneous purposes (Marks v The Shire of Swan
Hill [1974] VicRp 103; (1974) VR 896), or in a manner which would be contrary to
the statutory requirements for the exercise of the discretion
(Green v Daniels [1977] HCA 18; (1977) 13 ALR 1), but provided that it does not
offend such requirements, it may govern the exercise of the
discretion even to the extent that it will be departed from only
in exceptional circumstances (Legal Services Commission of New
South Wales v Stephens (1981) 2 NSWLR 697). The decision-maker
must never attribute to policy a status which precludes him from
forming a genuine discretionary judgment. He must be prepared
to consider each case on its merits, at least so to the extent
that he is prepared to exercise his discretion in the
exceptional case in a manner not conforming to the policy, and
always so that he will consider each case with a view to
determining whether it is such an exceptional case and, if it
is, whether the discretion ought to be exercised otherwise than
in accordance with the policy."