‘So Far As Is Reasonably Practicable’ Explained For Health And Safety

Health and safety legislation in the UK places a great deal of responsibility on employers, but it rarely demands the impossible. One phrase that appears again and again across regulations, guidance documents, and enforcement notices is “so far as is reasonably practicable.” For anyone managing a workplace, understanding this phrase is not optional. It sits at the heart of how employers are expected to approach risk, and getting it wrong can have serious legal and financial consequences.

This guide breaks down what the phrase means in plain English, how it is applied in practice, and what it means for your legal duties under UK law.

You can’t remove risk altogether.

The phrase “so far as is reasonably practicable” (sometimes abbreviated to SFAIRP) sets out the standard of duty that most health and safety legislation in Great Britain requires of employers. It first appears prominently in Section 2(1) of the Health and Safety at Work etc. Act 1974, which states that every employer has a duty to ensure, so far as is reasonably practicable, the health, safety and welfare at work of all employees.

What the phrase does not mean is that an employer must do everything conceivably possible to eliminate every risk. That standard is captured by a different and higher legal threshold: “so far as is possible.” The distinction matters enormously. Something may be technically possible to implement while still being wholly impractical given the cost, time, or disruption involved. The law does not require employers to go that far.

Instead, SFAIRP introduces a proportionality test. It asks whether the sacrifice required to control or remove a risk (measured in money, time, and effort) is proportionate to the level of risk involved. If the cost of a control measure is wildly out of step with the risk it addresses, the duty to implement it may not apply. If the risk is significant, however, the expectation is that substantial resources should be committed to managing it.

It is also closely linked to the concept of ALARP, meaning “as low as reasonably practicable.” While SFAIRP describes the legal standard, ALARP is the practical framework used to demonstrate compliance. Showing that a risk has been reduced to ALARP means demonstrating that all reasonably practicable control measures have been considered and implemented, unless the cost of doing so would be grossly disproportionate to the risk reduction achieved.

It’s a question of balance.

The most authoritative guidance on how to assess reasonable practicability comes from the Court of Appeal ruling in Edwards v National Coal Board (1949). In that case, the court described a weighing exercise in which the quantum of risk is placed on one side of a notional scale, and the sacrifice required to avert it is placed on the other. Only when the sacrifice is grossly disproportionate to the risk can an employer discharge their duty without implementing the measure.

What this means in practice is that the greater the risk, the less weight can be given to cost. A small financial saving will not justify leaving a serious hazard uncontrolled. Conversely, where a risk is minor and the cost of control is extremely high, the law may not require action. The key word throughout is proportion.

The table below illustrates how this balance typically plays out across different risk and cost scenarios:

The presumption under UK law always tilts towards implementing control measures. This is not a decision weighted in favour of commercial convenience or operational cost. It is weighted in favour of health and safety. Employers cannot use profit margins or budget pressures as justification for leaving preventable risks uncontrolled.

It is also important to recognise that the assessment is not a one-time exercise. Risks change as workplaces evolve, new equipment is introduced, or working practices are updated. What was reasonably practicable five years ago may no longer be sufficient if better control measures are now available at comparable cost. Regular review of risk assessments is therefore an essential part of demonstrating ongoing compliance with the SFAIRP standard.

For example, if it would take a month and cost 1 million pounds to put in place a control measure that would eliminate the need for one person to work at height on a task that is only going to be carried out once, this would be grossly disproportionate and not reasonably practicable.

But that doesn’t mean you don’t need to do anything to control the risk. There could be other control measures that would be easier to put in place to minimise the risk. Where these measures are proportionate, they would be reasonably practicable to implement.

In the example above, you still need to put control measures in place to reduce the risk of that worker suffering a fall during the work at height activity and ensure the work can be carried out safely.

Remember to consider the hierarchy of risk control when deciding the best control measures to manage your risks.

The greater the risk involved, the less consideration should be given to cost, and the more effort will be required to reduce the risk to comply with your duties.

Weighted in favour of health and safety

The decision to balance what is reasonably practicable isn’t black and white. It’s not a decision weighted in favour of the size of the business or the cost of a life. It’s a decision weighted in favour of health and safety. All employers, big and small, have the same duty: to protect people and prevent harm.

So, it’s not a case of thinking a control measure could eat into your profits or is slightly more costly than you expected, and it can be ruled out. If a risk is insignificant compared to the time and cost to mitigate it, it can be determined that control is not reasonably practical—in other words, grossly disproportionate.

The presumption will always be that the control measures should be implemented. The decision to balance risk and sacrifice will be weighted in favour of health and safety rather than balancing the cost and benefits of measures. Only where the control measures are grossly disproportionate to the risk can they be ruled out?

More money, time, and trouble should be spent controlling higher risks, which would be reasonably practicable.

For example, construction sites are high-hazard environments due to the nature of the work. You would expect more time and money to be spent on control measures in this work environment.

The HSE will not expect the working environment to be risk-free should they inspect your site, either routinely or following an accident. They will expect that you have adequately assessed the risks and reduced them as low as expected. If you are inspected, you must show that you have put suitable control measures proportionate to the risks involved.

Using common sense

In deciding what is proportionate and what measures come under ‘as far as is reasonably practicable’, you should apply common sense and relevant good practice guidance to the risk.

Good practice is often found in professional bodies, trade publications and the HSE. In most circumstances, compliance with good practice will (in most circumstances) be sufficient to demonstrate that risks have been reduced as low as reasonably practicable.

However, it is essential to apply the guidance to your specific business activity and ask yourself if any further measures could reduce the risk. Where further measures are highlighted, these should also be applied if, on the test of the remaining risk vs. the time and resources to put the control in place, you assess these control measures as proportionate.

Remember, unless the measures are grossly disproportionate and the risk insignificant in comparison, the weighting should always be on implementing the measures and reducing the risk. Not only will this help you comply with the law by applying measures that are ‘reasonably practicable,’ but it will also help keep your workforce safe and productive.

This article was written by Mathew Oldham (HSQE Consultancy Ltd). Mathew has over 20 years of experience in health and safety and an MSc (Hons) in Construction Management. Mathew is NEBOSH Health and Safety, Construction, Fire, Environment and Diploma qualified and CertIOSH.

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