Quick answer: "Reasonably practicable" is the legal test that tells a PCBU how far to go to manage risk under WHS law. You must do what is reasonably able to be done, taking into account the likelihood of harm, the seriousness of harm, what is known about the hazard, the controls available, and the cost of those controls.
Last reviewed: March 2026 by the BlueSafe Technical Team. Reflects current Australian WHS laws and regulations.
This phrase sits at the centre of Australian WHS law. It is the standard that decides whether a control measure should have been implemented, so businesses need to understand it in practical terms, not just legal language.
What is the legal definition of 'reasonably practicable'?
The model WHS Act uses a balancing test. The PCBU must do what is reasonably able to be done to ensure health and safety, and the decision is made by looking at five factors.
| Factor | What to consider | Example |
|---|---|---|
| Likelihood of the hazard or risk occurring | How likely is the harm if nothing changes? | A fall from a roof is less likely than a minor slip, but the consequences are much more severe |
| Degree of harm that could result | What is the worst realistic outcome? | Fracture, fatality, or long-term illness |
| What you know or ought to know | What is already known about the hazard and available controls? | Manufacturer instructions, codes of practice, incident history |
| Availability and suitability of controls | Are there controls that work in this context? | Guardrails, isolation, safer equipment, work redesign |
| Cost of controls | Is the cost grossly disproportionate to the risk? | A basic guardrail is usually not too expensive compared with a fatal fall risk |
The key point is that cost is not the first question. The first question is always whether a control is needed to remove or reduce a real risk.
How is 'reasonably practicable' applied in practice?
A good PCBU does not treat this phrase as a defence after the fact. It uses it as a decision-making process before the work starts.
- Identify the hazard.
- Ask how likely the harm is and how serious it could be.
- List the controls you already know about.
- Compare the available controls and pick the most effective one that is reasonably achievable.
- Record why the chosen control is the right one for the circumstances.
For example, if workers must work near an open edge, the first option should be to eliminate the need to work at height. If that is not possible, the next step might be edge protection, scaffolding, or another engineering control. Personal protective equipment only comes after more effective controls have been considered.
What is the role of cost?
Cost matters, but only as part of the full analysis. A business should compare the cost of the control with the level of risk and the effectiveness of other controls.
The law does not say a PCBU must spend any amount of money no matter what. It does say a PCBU cannot ignore a known effective control simply because it would be inconvenient, slow the job down, or reduce margin.
Courts generally expect this kind of reasoning:
- if the risk is high, a stronger control is usually justified
- if a control is cheap and effective, it is hard to justify not using it
- if a control is expensive but prevents catastrophic harm, cost alone will rarely be enough to reject it
What is the difference between 'reasonably practicable' and 'reasonably foreseeable'?
The two ideas are related but not identical.
| Term | Meaning | Why it matters |
|---|---|---|
| Reasonably foreseeable | Could a prudent person expect the hazard or harm to happen? | If the risk is foreseeable, you need to think about controls |
| Reasonably practicable | What should actually be done about the risk? | This is the legal standard for the control decision |
In practice, a foreseeable risk usually triggers the need for a reasonably practicable response. That is why businesses should not wait for an incident before acting.
How do you assess a specific hazard?
Use a simple written checklist:
- describe the hazard in plain language
- identify who could be harmed
- rate the likelihood and the consequence
- list all possible controls
- choose the highest-level effective control that is reasonably practicable
- explain why lower-level controls were not enough
- set a review date and a responsible person
This makes the decision transparent. If a regulator later asks why a particular control was not used, the business can show the reasoning instead of guessing after the fact.
State and territory variations
The information on this page is based on the Model WHS Act and Model WHS Regulations published by Safe Work Australia, adopted with some variations across most jurisdictions.
| Jurisdiction | Regulator | Key notes |
|---|---|---|
| NSW | SafeWork NSW | Uses the model concept of reasonably practicable and now has NSW-specific code duties from 1 July 2026 |
| VIC | WorkSafe Victoria | Uses the OHS Act 2004 and different wording in some provisions |
| QLD | Workplace Health and Safety Queensland | Model framework |
| SA | SafeWork SA | Model framework |
| WA | WorkSafe Western Australia | Model framework |
| TAS | WorkSafe Tasmania | Model framework |
| ACT | WorkSafe ACT | Model framework |
| NT | NT WorkSafe | Model framework |
Always check the exact law and regulator guidance that applies to your business.
Related guides
- How to Conduct a WHS Risk Assessment
- Hazard Identification at Work
- WHS Act, Regulations and Codes of Practice
Frequently asked questions
What does 'reasonably practicable' mean in WHS law?
It is the legal test for how far a PCBU must go to manage a risk. The answer depends on the likelihood of harm, the degree of harm, the controls available, and the cost of those controls.
Who decides what is reasonably practicable?
Courts decide in enforcement proceedings, but regulators and safety professionals assess it in the same way when they review a workplace decision.
Does 'reasonably practicable' mean I have to eliminate every risk?
No. It means eliminate risks where that is reasonably practicable, and otherwise minimise them so far as is reasonably practicable.
How does 'reasonably practicable' relate to cost?
Cost is only one factor, and it is not the first factor. A business cannot reject a known effective control just because it would cost money.
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