The general protections provide for what is commonly referred to as a “reverse onus of proof”, that is to say assuming that there is some reasonable basis for the inference, the onus of dispelling it lies upon the decision maker.
This is what the Fair Work Commission’s general protections benchbook says about the issue.
“How can the presumption be rebutted?
The court must consider why the adverse action was taken. This involves consideration of the person or decision-maker’s particular reason for taking the action and consideration of all the facts of the case at the time the decision was made, including those related to the adverse action.19F
The person who is seeking to rebut the presumption will need to provide evidence about the reason for taking the adverse action and/or the intention at the time of taking the adverse action. In the case of an organisation or corporation, the reason or reasons motivating the person(s) in the organisation or corporation who effectively made the decision to take the adverse action will be significantly relevant. In that context, it is important to identify the effective decision-maker(s) and their motives.20F21
To rebut means to refute by evidence or argument, to oppose something by proving the opposite.
It will ordinarily be difficult to rebut the statutory presumption if no direct evidence by the person or decision-maker(s) who took the adverse action is given.21F
Direct evidence of the decision maker’s state of mind, intent or purpose will be considered, and the credibility of the decision-maker will be examined.2F It will be up to the Court or Commission to consider whether the decision-maker’s evidence as to the reasons for taking the action is accepted. It is open to the other party to call evidence to demonstrate that the decision-maker’s real reason for taking the action was not what they said it was.
Direct testimony from the decision-maker which is accepted as reliable is capable of discharging the burden upon an employer. However, direct evidence of the reason why a decision-maker took adverse action, which may include positive evidence that the action was not taken for a prohibited reason, may be unreliable because of other contradictory evidence given by the decision-maker or because other objective facts are proven which contradict the decision-maker’s evidence. 23F “