The Fair Work Act provides a reverse onus of proof in general protections’ cases. That is to say that the onus of disproving that the motivation for the alleged act was unlawful rests upon the defendant (normally an employer) once a coherent case for the allegation is established. But what is the level of persuasion which is required by an applicant before the reverse onus kicks in?
The effect of s.361 of the Act is to reverse the legal onus in relation to the reason or reasons for which the adverse action was taken. That is to say, at the end of the trial of fact, the question will be whether the Respondent has established, on the civil standard, that the action taken was not taken for a reason, or for reasons which included a reason, proscribed by the legislation. That question is to be answered by reference to all of the evidence which bears upon it: CFMEU v Anglo Coal (Dawson Services) Pty Ltd  FCAFC 157 per Jessup J at .
Section 361 of the Act comes into operation only after it has been established “that adverse action was taken” and “that a relevant workplace right exists” “as an objective fact”.
In Board of Bendigo Regional Institute of Technical and Further Education v Barclay  HCA 32; (2012) 248 CLR 500 (“Barclay”), French CJ and Crennan J explained at  that:
o Sections 360 and 361, in Div 7 of Pt 3-1, make it easier than it otherwise would be for an employee to establish a contravention of the protective provisions in Pt 3-1, including s 346. Section 360 provides that, for the purposes of Pt 3-1, “a person takes action for a particular reason if the reasons for the action include that reason”. Section 361(1), … casts a burden of proof on an employer to show that it did not take action for a prohibited reason …
Gummow and Hayne JJ stated as follows at :
o In determining an application under s 346 [it is necessary to] assess whether the engagement of an employee in an industrial activity was a “substantial and operative factor” as to constitute a “reason”, potentially amongst many reasons, for adverse action to be taken against that employee. In assessing the evidence led to discharge the onus upon the employer under s 361(1), the reliability and weight of such evidence [is] to be balanced against evidence adduced by the employee and the overall facts and circumstances of each case; but it [is] the reasons of the decision-maker at the time the adverse action was taken which [is] the focus of the inquiry.
In BHP Coal Pty Ltd v Construction, Forestry, Mining and Energy Union  FCAFC 132, Flick J (with whom Dowsett J agreed) stated at :
o Contrary to the approach of Isaacs J in Pearce, a factor that may “enter … into the reason[ing]” process of an employer does not constitute a “reason” for the purposes of s 360 if that factor does not amount to “a substantial and operative reason” for the taking of adverse action. The fact-finding task imposed by s 346 is to filter out those factors that may have passed through the mind of an employer and to determine what was the “substantial and operative” reason or reasons for taking adverse action. If any one of those “substantial and operative” reasons was a proscribed reason, s 360 operates to confirm that the taking of action for that reason is prohibited.
The principles In Barclay were summarised, as follows, by the Full Court of the Federal Court of Australia in State of Victoria (Office of Public Prosecutions) v Grant  FCAFC 184 at :
o – The central question to be determined is one of fact. It is: “Why was the adverse action taken?”
o – That question is to be answered having regard to all the facts established in the proceeding.
o – The Court is concerned to determine the actual reason or reasons which motivated the decision-maker. The Court is not required to determine whether some proscribed reason had subconsciously influenced the decision-maker. Nor should such an enquiry be made.
o – It will be “extremely difficult to displace the statutory presumption in s 361 if no direct testimony is given by the decision-maker acting on behalf of the employer.”
o – Even if the decision-maker gives evidence that he or she acted solely for non proscribed reasons other evidence (including contradictory evidence given by the decision-maker) may render such assertions unreliable.
o – If, however, the decision-maker’s testimony is accepted as reliable it will be capable of discharging the burden imposed on the employer by s 361.
Heraud v Roy Morgan Research Ltd  FCCA 185 (5 February 2016)