Under sec 107 of the Fair Work Act 2009, an employee is required to provide an employer with notice of the taking of leave and must advise the employer of the period, or expected period, of the leave. This includes personal leave, which nowadays by definition includes sick leave. Under sub-sec 107(3), an employer is entitled to require that the employee provide evidence which, in the case of sick leave, would satisfy a reasonable person that “ the employee is not fit for work because of a personal illness, or personal injury, affecting the employee”.(sub-sec 97)
In Australian and International Pilots’ Association v Qantas (2014) FCA 32 Justice Rares of the Federal Court was called upon to determine whether disciplinary action taken by Qantas against a pilot who had failed to provideots Association v Qantas Airways Ltd  FCA 32 Justice Rares was called upon to review whether disciplinary action taken by Qantas against a pilot for failing to provide evidence in the form of “a written report from his doctor that clearly indicated his diagnoses, prognosis, capacity to return to your pre-injury duties and the anticipated timeframe” constituted unlawful adverse action contrary to sec 340(1) of the Act which protects workplace rights, in this case the taking of sick leave under the relevant enterprise agreement.
In a very interesting approach to the issue, His Honour concluded that the statutory work health and safety obligations upon Qantas were sufficient for the court to imply “a contractual right of Qantas to require its pilots to provide medical evidence of the kind it sought from them and for pilots to attend a meeting to discuss matters concerning their conditions arises from the obligations imposed on Qantas by both the agreement itself and the Work Health and Safety Act.”
“An employee’s… entitlement to take sick leave does not displace the contractual relationship in which, at some point, the employer is entitled to make its own business arrangements to adjust for the impact that the leave caused by the sickness of the employee will have on it and to address its obligations under the Work Health and Safety Act and its analogues.”
Thus Qantas’ actions could not constitute unlawful adverse action.