As I pointed out in a post published yesterday, it is unlawful for an employer to take adverse action against an employee or prospective employee because of any of the specified protected characteristics of the employee provided for by sec 351 of the Fair Work Act, such as age, sex marital status etc.
However the provision goes on to expressly excuse action that is, inter alia, “taken because of the inherent requirements of the particular position concerned.
But what does this mean. Here is the answer.
“As to the last aspect of s 351, namely s 351(2)(b) and the reference to “the inherent requirements of the particular position”. It may be accepted that “the inherent requirements of the particular position” is not a reference to every requirement of that position: cf. X v Commonwealth  HCA 63, (1999) 200 CLR 177. There in issue, amongst other things, was a provision which provided that discrimination was not unlawful if an employee was “unable to carry out the inherent requirements of the particular employment”. McHugh J observed (at 187 to 188) in respect to this provision found in s 15(4)of the Disability Discrimination Act 1992 (Cth):
The inherent requirements of the particular employment
 Whether something is an “inherent requirement” of a particular employment for the purposes of the Act depends on whether it was an “essential element” of the particular employment. However, the inherent requirements of employment embrace much more than the physical ability to carry out the physical tasks encompassed by the particular employment. Thus, implied in every contract of employment are obligations of fidelity and good faith on the part of the employee with the result that an employee breaches those requirements or obligations when he or she discloses confidential information or reveals secret processes. Furthermore, it is an implied warranty of every contract of employment that the employee possesses and will exercise reasonable care and skill in carrying out the employment. These obligations and warranties are inherent requirements of every employment. If for any reason – mental, physical or emotional – the employee is unable to carry them out, an otherwise unlawful discrimination may be protected by the provisions of s 15(4).
 Similarly, carrying out the employment without endangering the safety of other employees is an inherent requirement of any employment. It is not merely “so obvious that it goes without saying” – which is one of the tests for implying a term in a contract to give effect to the supposed intention of the parties. The term is one which, subject to agreement to the contrary, the law implies in every contract of employment. It is but a particular application of the implied warranty that the employee is able to and will exercise reasonable care and skill in carrying out his or her duties.
 It would be extremely artificial to draw a distinction between a physical capability to perform a task and the safety factors relevant to that task in determining the inherent requirements of any particular employment. That is because employment is not a mere physical activity in which the employee participates as an automaton. It takes place in a social, legal and economic context. Unstated, but legitimate, employment requirements may stem from this context. It is therefore always permissible to have regard to this context when determining the inherent requirements of a particular employment.
Jutices Gummow and Hayne observed in respect to s 15(4) as follows (at 208):
 Section 15(4)(a) contains a number of elements that must be taken into account in seeking to apply it. First, the inquiry is whether “because of [the person’s] disability” he or she would be unable to carry out the inherent requirements of the particular employment. That is, the search is for a causal relationship between disability and being unable to carry out the inherent requirements of that employment. Secondly, the provision applies only if the person would be unable to carry out those requirements. No doubt inability must be assessed in a practical way but it is inability, not difficulty, that must be demonstrated. Thirdly, the requirements to which reference must be made are the “inherent requirements of the particular employment”.
 The reference to “inherent” requirements invites attention to what are the characteristic or essential requirements of the employment as opposed to those requirements that might be described as peripheral. Further, the reference to “inherent” requirements would deal with at least some, and probably all, cases in which a discriminatory employer seeks to contrive the result that the disabled are excluded from a job. But the requirements that are to be considered are the requirements of the particular employment, not the requirements of employment of some identified type or some different employment modified to meet the needs of a disabled employee or applicant for work.
 It follows from both the reference to inherent requirements and the reference to particular employment that, in considering the application of s 15(4)(a), it is necessary to identify not only the terms and conditions which stipulate what the employee is to do or be trained for, but also those terms and conditions which identify the circumstances in which the particular employment will be carried on. Those circumstances will often include the place or places at which the employment is to be performed and may also encompass other considerations. For example, it may be necessary to consider whether the employee is to work with others in some particular way. It may also be necessary to consider the dangers to which the employee may be exposed and the dangers to which the employee may expose others.”
Robinson v Western Union Business Solutions (Australia) Pty Ltd  FCA 1913 delivered 30 November 2018 per Flick J