[65] … Neither involved a deliberate breach of a duty of confidentiality, nor a breach of a duty of impartiality. To release confidential information in circumstances where you know you should not release it cannot usefully engage a test of 'causation'. In the case of impartiality, both statute and common law principles dictate a different approach. The relevant administrative law principles are those in relation to bias, which encompasses both prejudgment and partiality based upon an interest or association. Both actual bias and a reasonable apprehension of bias disqualify a decision-maker and, if a decision has been made, invalidate the decision. In a statement of principle adopted by Gummow J in IW v City of Perth [(1997) 191 CLR 1 at 51; [1997] HCA 30]:
'Even though the decision-maker may in fact be scrupulously impartial, the appearance of bias can itself call into question the legitimacy of the decision-making process.'
[66] Public confidence in public administration justifies such a principle, which cannot be diminished by asking whether the decision-maker would have made the same decision absent the appearance of bias.
250 The applicant's submission as to the "causal test" contended for was rejected by the Commission at [10.340]–[10.350]. Its reasons for doing so included that the language of s 8(1)(b) referring to conduct of a public official that constitutes or involves the partial exercise of an official function is not to be read down or as not applying to or including such conduct where the outcome of the exercise of the official function would have been the same, but for the intrusion and influence of the private interest. The Commission considered that to do so "would not promote the integrity objects of the ICAC Act but, rather, would limit the field of conduct which would fall within its terms" ([10.341]).
251 Focusing on the interactions of ss 8 and 9 of the Act, the Commission also said at [10.348]:
It is a more harmonious construction of the interaction of s 8 and s 9 to have regard to Priestley JA's view [in Greiner at 182, 184] of s 8 as prima facie capturing as corrupt 'any conduct adversely affecting the honest and impartial exercise of official functions' and s 9 as proceeding 'on the footing' that the matters it addresses 'are capable of definite statement'. On this approach, it is more consistent with the context and purpose of the ICAC Act for issues such as any mental element of a criminal or disciplinary offence, dismissal matter or breach of an applicable code of conduct to be considered at the s 9 stage rather than to incorporate a prescriptive mental element into the s 8(1) (b) question. (Footnote omitted.)
252 The reference to "issues such as any mental element of a criminal … offence" harks back to [10.340], where reference is made to the decision in Maitland at [84] and [87]. In that case, the offence with which the Minister was charged was wilful misconduct in public office. There was an issue as to whether the trial judge had misdirected the jury in relation to the mental element of that offence in circumstances where the Minister had embarked on a transaction for purposes which included proper purposes and an improper purpose (so that the improper purpose was not the sole purpose). The Court held that the direction to the jury was not adequate. Fundamentally, it was necessary for the prosecutor to establish beyond reasonable doubt that the Minister exercised and intended to exercise the relevant power for the purpose of conferring the extraneous benefit, that not being the sole purpose. That meant that the prosecutor had to exclude as a reasonable possibility that the power was exercised for the other purpose or purposes.
253 At [84], the Court in Maitland concluded:
