There has been a significant case in the Federal Circuit Court about adverse action for exercising a workplace right, and the evidence which is required to establish (notwithstanding the reverse onus of proof) of a sufficient causal link between the taking of the adverse action and the exercise of the workplace right or rights.
In Celand v Skycity Adelaide Pty Ltd  FCCA 399 Borwn J said
“In Construction, Forestry Mining & Energy Union v BHP Coal Pty Ltd the High Court said as follows:
o “Section 346 does not direct a court to enquire whether the adverse action can be characterised as connected with the industrial activities which are protected by the Act. It requires a determination of fact as to the reasons which motivated the person who took the adverse action.”
Even if the temporary deferral of Ms Celand’s promotion can be characterised as discriminatory and so come within the purview of item 1(d) of section 342 that adverse action must have been taken because of Ms Celand’s industrial activity. Connection is not enough.
In Sayed Perry J said as follows:
o “This difference between a “connection” and a “reason” may, with respect, be elusive. Possession of a protected attribute is clearly insufficient, and it may also be accepted that if the occasion for adverse action happens to coincide with manifestation of a protected attribute (such as political opinion or industrial activity), that is insufficient. If, however, more than this is meant by the use of the term “connection” then it seems to me as a matter of fact in a given case there may well be an overlap with a “reason” for the adverse action. So too the distinction between an employer not having to prove adverse action was “entirely disassociated” from a prohibited reason, but having to prove the prohibited reason was not a “substantive and operative” reason. Repeating that these will be questions of fact to be determined on the evidence in a particular case does not remove the difficulty of the somewhat fine distinctions being drawn in the authorities. With respect, they also illustrate the difficulties in paraphrasing, or moving away from, the statutory language which here relevantly requires that an employer prove action was not taken for reasons which “included” a prohibited reason.”
As the High Court in BHP Coal emphasised, whether an action of an employer is taken for a prohibited reason is a question of fact. The question of fact to be resolved being why was adverse action taken and was it because of a reason protected by the FWA. Such an inquiry will generally involve an examination of the state of mind of the decision-maker concerned, although it is not limited solely to this issue.
Overall, I do not consider that Ms Celand has established that either her unionism or her exercise of any workplace right, which I do not think in any event has been confirmed, was the substantive and operative reason why Mr Devine initially decided not to promote her. In any event, given the temporary and amorphous nature of any discrimination, which she suffered, I further do not believe that this conduct can be characterised as adverse action.