An employer is entitled to issue an instruction to an employee if it is lawful and reasonable. A direction or instruction does not cease to be reasonable merely because it may not be best practice or objectively the best course to take.
“It seems to me that the applicant’s arguments as to why she did not need training essentially amount to her view that, in the circumstances, it was not reasonable for her to attend the training. In Briggs v AWH Pty Ltd  FWCFB 3316, the Full Bench of the Commission considered the second leg of the relevant test as to the reasonableness of an employer’s direction. At  the Full Bench said:
‘ The determination of whether an employer’s direction was a reasonable one (there being, as earlier stated, no contest in this case that AWH’s direction was lawful) does not involve an abstract or unconfined assessment as to the justice or merit of the direction. It does not need to be demonstrated by the employer that the direction issued was the preferable or most appropriate course of action, or in accordance with “best practice”, or in the best interests of the parties. The proper approach to the task is that identified by Dixon J in The King v Darling Island Stevedoring and Lighterage Company Limited; Ex Parte Halliday and Sullivan in the following terms:
“But what is reasonable is not to be determined, so to speak, in vacuo. The nature of the employment, the established usages affecting it, the common practices which exist and the general provisions of the instrument, in this case an award, governing the relationship, supply considerations by which the determination of what is reasonable must be controlled.” (endnote omitted)”
Dias v Commonwealth Bank (2019) FWC 5479 delivered 19 September 2019 per Sams DP