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  1. Summerfield remains good law and a common sense evaluative test to determine how two injuries have arisen and whether they share a close causal connection is still required.
  2. The Court has left open some of the ongoing arguments that are available to insurers in respect of separating impairments – most notably where two injuries might be caused by employment duties, of a different nature.
  3. Thorough investigations should be conducted into the cause of all injuries, especially injuries said to be consequential, to determine whether they might be due to two separate work related causes.

Return to Work Corporation (SA) v English; Williams v Return to Work Corporation (SA) [2023] SASCA 125 (23 November 2023)

 The Full Court of the Court of Appeal delivered its decision in the matters of Return to Work Corporation (SA) v English (English) and Williams v Return to Work Corporation (SA) (Williams). These matters were heard together in March 2023, as they involved similar issues relating to the combination of impairments under ss 22(8)(c) and 58(6) of the Return to Work Act 2014 (RTW Act). 

This decision provides important further clarity about the circumstances in which impairments from multiple injuries are capable of being combined following a permanent impairment assessment under s 22 of the RTW Act in some (but not all) circumstances, and in a general sense reiterates the need to carefully consider the need to adopt a common sense evaluation of the factual circumstances giving rise to impairments as a basis to consider whether they should be combined, or separated.    

Key takeaways

Injuries that have occurred due to the same duties of employment and over the same period of employment may be combined, and so it is important to consider obtaining evidence about the conditions and specific duties of a worker early in a claim. 

In the case of consequential injuries arising from an injury caused in the workplace, you should consider whether there is a close connection between the two resultant injuries/impairments (i.e. a chain of causative events), and consider whether that chain might be broken by an external, intervening event.

The Full Court has provided further clarifying examples where impairments will be combined, but the decision is not exhaustive, and the Court has explicitly noted that it is clear that the legislation should not allow for the combination of all impairments.



Mr Williams sustained an injury to his right knee in May 2013 whilst climbing scaffolding in the course of his employment as an electrician. He underwent surgery and in September 2014 resumed work with a new employer.

Between September 2014 and May 2015, Mr Williams undertook primary sedentary tasks, however in May 2015, his duties changed and he was required to perform more physically demanding work including regularly working in a crouched position with bent knees and kneeling. Mr Williams reported gradually worsening symptoms of pain in his right knee, and his left knee. Mr Williams sought medical treatment and had total knee replacements in both knees. 

Mr Williams underwent a permanent impairment assessment pursuant to s 22 of the RTW Act, in relation to the 2013 right knee injury, and the left and right knee injuries sustained in 2015. 


Mr English sustained a work injury on 4 March 2019 in the course of his work as an arborist, when a rope attached to a heavy branch swung and collided with the back of his neck, pinning his neck against a cherry picker. As part of his medical treatment for that work injury, he was prescribed pain medication (Lyrica).

On 10 May 2019, Mr English was undertaking quoting work when he experienced an episode of light-headedness and fell at work. As a result of that fall, Mr English injured his right quadriceps.

In due course, Mr English underwent a permanent impairment assessment pursuant to s 22 of the RTW Act. 

Key Findings

The Court provided the following relevant commentary.

  • That there was no reason to depart from the prior decisions in Preedy (2018) 131 SASR 86 and Summerfield (2021) 138 SASR 175.
  • Impairments may arise from the same cause even if they each arise from multiple causes and may be explained by multiple events. 
  • Impairments may arise from the same cause even though there is not a complete match between the causal events. Therefore, an additional event or events in the causal explanation of an impairment does not necessarily prevent it from being combined with another impairment. 
  • There is no basis in the text of the legislation to confine the combination of impairments to circumstances where the later impairment involves a direct physiological consequence of an earlier injury without the involvement of any additional events other than what might be described as the ordinary activities of life. 
  • Whilst there are limits to what can be combined, there is no basis in the text to support a narrow view of those limits. 
  • It is necessary to consider the causal explanation for each of the impairments, and in particular consider any differences between them, including whether any additional events of integers are of a nature or significance that means the impairments cannot be said to arise from the same injury or cause. Whilst this assessment is informed by common sense, common sense is not the touchstone and further, the assessment is not to be approached in a manner that is overly technical or artificial. 

Kourakis CJ delivered a dissenting judgment on the proper construction of s 22(8)(c) of the RTW Act. 

His Honour considered that the term “same cause” in s 22(8)(c) of the RTW Act should be limited to mean the same workplace activity. His Honour reasoned that s 22(8)(c) of the RTW Act requires that the second impairment itself can be traced back to the cause of the first impairment and found that it is not sufficient that the cause of the secondary impairment can be traced back to the workplace activity which caused the primary impairment. 

Therefore, Kourakis CJ found that combination under s 22(8)(c) of the RTW Act requires that both impairments have their origin in and progress from, the same cause (our emphasis added). 

As will be seen below, this dissenting opinion on the construction of the relevant provision did not result in a different outcome in the matter of Williams, however it did in the matter of English. 


In both matters, the Full Court held that the relevant impairments sustained by Mr English and Mr Williams should be combined.

In the case of English, Justices Doyle and Bleeby held that a causal chain existed between his original neck injury he sustained at work, leading to the use of medication which in turn lead to his fall. As the chain of events was unbroken by an external event, the injuries arose from the same cause, which implies a common sense consideration of the facts of a case and the closeness of the connection between two impairments is essential to the application of the ‘same cause’ test provided in s22(8)(c), but that the test should be considered a broad one and does not require that two impairments share identical causes.

They must, instead, be closely related and so the relevant test is concerned with the association between any two impairments.

Kourakis CJ dissented, answered the question in the negative, and held that combination under s 22(8)(c) requires that both impairments have their origin in, and progress from the same cause.  

In Williams, the Full Court held that because there had been earlier, factual findings that the worker’s bilateral knee injuries arose from the same duties and over the same period (climbing a ladder with both legs, causing trauma to both knees) that under s 22(8)(c) of the RTW Act the resultant impairments should be combined.

The important aspect of that decision is that after a detailed factual analysis, the worker’s knee injuries were found to arise from a very narrow, confined event or series of events, noting that the Court did not descend into the most granular assessment of the cause and suggest that each micro-trauma (i.e. each step up the ladder) would have involved one, or the other knee.

Instead, they construed the particular task/duty that the worker was performing which involves walking up and down a ladder to be a cause common to both knee impairments, and so they were found to arise from the same cause. 

Both decisions highlight the importance of thorough investigations being conducted, right from the outset of a matter even though lump sum decisions will not be made for month, or years after an injury has been suffered.

Small, and at times insignificant facts could play a key role in the assessment of the causative factors which give rise to any two impairments, and may not be available to a decision maker at the time of a lump sum decision being made due to the passage of time, noting that generally speaking the broad interpretation of the ‘same cause’ test in s22(8)(c) is likely to favour the combination of impairments sharing a causal relationship.

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