See obiter remarks entitled ‘Disturbing undercurrents’ by Flick J in Minister for Immigration and Citizenship v SZQRB  FCAFC 33.
See also - for a discussion about how personal non-compellable powers which may be exercised in the ‘public interest’ must still take into account relevant factors. It is an error to make a decision ‘irrespective of’ relevant factors: 
The often-overlooked section 25C of the Acts Interpretation Act (Cth) provides:
Where an Act prescribes a form, then strict compliance with the form is not required and substantial compliance is sufficient.
In Australian Institute of Marine and Power Engineers v Secretary, Department of Transport (1986) 71 ALR 73, the respondent argued that the secrecy provision in the Income Tax Assessment Act 1936, section 16 (as it then existed) which required a public servant to keep certain matters secret unless disclosure was part of the public servant’s usual ‘duty’ (a word appearing in the then section 16), meant that the requirement to provide reasons for administrative decisions under the Administrative Decisions (Judicial Review) Act 1977, s 13(2) did not apply.
This was rejected. Gummow J noted that the ‘duty’ of a public servant included a duty to comply with other laws, such as the obligation to provide reasons under the Administrative Decisions (Judicial Review) Act. At 84-85 his Honour said:
The [duty] indeed required … observance and compliance with obligations arising at common law and in equity, save as excluded or supplanted by statute: see Hogg Liability of the Crown pp 147–160. These general law obligations would include those of care and skill (Carpenter’s Investment Trading Co Ltd v Commonwealth (1952) 69 WN(NSW) 175 at 178), fidelity (Reading v Attorney-General  AC 507) and confidentiality (Commonwealth v John Fairfax and Sons Ltd (1980) 147 CLR 39 at 50–1 ; 32 ALR 485). Also included, in my view, in the exception is what is appropriate to discharge or satisfy requirements or duties imposed pursuant to procedures existing under statutes other than the Tax Act.