Reasonably practicable
Reasonably practicable is the qualifier on almost every WHS duty: it means doing what can reasonably be done in the circumstances, having regard to the likelihood of harm, the degree of harm, what is known about the hazard, the availability and suitability of controls, and the cost of controls. Cost is always the last factor.
Legal context
Section 18 of the model WHS Act defines "reasonably practicable" using a five-factor test: (a) the likelihood of the hazard or risk occurring; (b) the degree of harm that might result; (c) what the person concerned knows or ought reasonably to know about the hazard / risk and ways of eliminating or minimising it; (d) the availability and suitability of ways to eliminate or minimise the risk; and (e) only after assessing (a)–(d), the cost associated with available ways of eliminating or minimising the risk. Cost can only justify not implementing a control where the cost is grossly disproportionate to the risk — the threshold is high. The test is what a reasonable person in the duty-holder's position would do, knowing what they ought reasonably to know.
Practical use
Practically, this means risk assessments need to demonstrate the (a)–(d) reasoning before any (e) cost consideration. A risk assessment that says "we considered Control X but it was too expensive" without the prior four-factor reasoning is not a defensible record.
Regulator references
The binding-law and regulator-guidance sources behind this term.
Common questions
Does cost ever justify not implementing a control?
Only when the cost is grossly disproportionate to the risk — a high threshold. The factor is the last consideration after likelihood, degree of harm, knowledge, and the availability and suitability of controls have been weighed.
Where this shows up in RAE IQ
Related terms
Primary duty of care
The primary duty of care (model WHS Act s19) is a PCBU's overarching duty to ensure, so far as is reasonably practicable, the health and safety of workers and other persons at the workplace. It is the foundation duty from which most other WHS obligations flow.
Hierarchy of control
The hierarchy of control is the rank-ordered preference for risk treatment: eliminate the hazard, then substitute, then isolate, then engineer, then administer, then PPE as a last resort. Higher controls reduce risk more reliably than lower controls because they do not depend on people behaving correctly under stress.
ALARP
ALARP — As Low As Reasonably Practicable — is the principle that risk must be reduced as far as is reasonably practicable, applying hierarchy-of-control reasoning, and only stopping when further control would be grossly disproportionate to the residual risk. It is the operational expression of the s18 reasonably-practicable test.
Platform pillars
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47 WHS and HSWA terms with legal context, FAQs and regulator references.