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In a recent publication (https://theconversation.com/many-elite-athletes-live-with-health-impacts-long-after-they-retire-should-they-carry-all-the-costs-286336 on 9 July 2026), the issue of ACC cover for professional sports athletes arose. In a nutshell, the contention was that sports people should take own responsibility for osteoarthritis arising from their sports as they retire from their active sports life. Many commentators made the point that sports professionals should fund their medical treatments privately, and not receive ACC cover.

I disagree.

First of all: the accident compensation scheme is a no-fault system. Fault or negligence, blame allocation or responsibility for an injury or subsequent consequential injury or condition, such as osteoarthritis, is entirely irrelevant. The design of the accident compensation law has evolved through multiple versions of the statute. Before the ACC law came into force in New Zealand, any liability for injury originated in the law of torts, which is a legal area concerned with fault allocation to determine liability. The New Zealand legislator decided to abandon the element of fault entirely and whilst there were several different versions of the law as it is in force today, fault never was relevant.

And that makes sense because where would one want to draw the line? High risk sports may pave the way for injury and also future injury (think: concussion and its effects over the years, or osteoarthritis as a result of injury or even repeated injury during the active sports life); however, high risk work does so, too. How many forrestry workers die during a year in New Zealand? Between four and five workers. How many workers are injured within other high risk work like mining? or port workers? Approximately two per year. There are many other risky professions - risks that eventuate later in life, such as asbestos exposure which causes mesothelioma (see the famous case Trevarthan v Accident Compensation Corporation[2019] NZHC 1581 .

The point I am making is: there was a good reason why the legislator has decided to eliminate responsibility or fault from the accident compensation scheme. It is impossible to make some people responsible for injuries, and some not. Each case is individually different. Fault or personal blame for an injury is misplaced because no one wants to be injured in the first place, and accidents happen - and with them, long term consequences develop. It is always easy to point the finger to personal liability, however, if we take that approach, it is questionable whether the ACC scheme would still be functional?

Consequential injury from sports for example may be foreseeable. However, that is exactly what the law of torts test involves - foreseeability and reasonablness in order to allocate fault. Would this add value or rather complicate the legal tests, thus, create more uncertainty than certainty?

There is no benefit in starting to divide up ACC liability for certain professions, risk categories of activities etc.

For every day people, who are not professional athletes, the lesson is: proactive prevention is doable, usually at low costs; reactive medical treatment is costly. For professional sports people the lesson may be to understand the medical causal connection between the typical risks in the particular sports to develop certain conditions and have medical expertise to support that. From a financial perspective, private health insurance can hedge future medical extra costs if need be. The ACC cover is not lost though and still takes priority. If ACC is liable to cover an initial injury or a consequential injury, then the private health insurance is not required to fund treatment. This can instead be used for other health needs. The legal basis for such cover depends on the individual circumstances of the case. It would be incorrect to state that all sports injuries would be work related gradual process injuries, and vice versa, it would also be incorrect to state that only traumatic injuries would attract cover. At the end of the day, it comes down to the medical evidence in the individual case. Every time.

Cover for treatment injuries

This is a complex area of the accident compensation law which is concerned with injuries that result from medical treatment or the lack or delay of medical treatment. Section 32 Accident Compensation Act 2001 provides cover for injuries caused by medical treatment or the failure to provide medical treatment in a timely manner, however, only if the injury is not due to a necessary part of the treatment or an ordinary consequence, which typically occurs following a certain medical treatment.

It sounds straightforward, but it is not.

One important landmark case is the case of McEnteer v Accident Compensation Corporation [2010] NZAC 126, the Court of Appeal determined -

[20] We consider that s32(1)(c) requires an analysis that is rooted in the facts of the particular· case - what was the injury suffered? Was it suffered in the course of the treatment undertaken? Was that injury a necessary part or ordinary consequence of that treatment? The third question in particular requires expert opinion, but not expert opinion in the abstract; rather, it requires expert opinion reflecting what actually occurred

Another important case - ACC v Adlam [2018] 2 NZLR 102 - was about cover for an injury due to the delay in diagnosis and treatment in a timely manner. Here, the Court of Appeal decided -

• [61] ... in order for there to be a treatment injury as a result of failure to provide treatment it is necessary to show that an alternative treatment that would have prevented the injury suffered could and should have been given having regard to the clinical indications at the time of the alleged failure.

• [62] Taken as a whole the provisions indicate a legislative intent to limit cover for persons who suffer injury while undergoing treatment, rather than providing cover for all those who suffer. The injury said to be a treatment injury must be the consequence of a departure from appropriate treatment choices and treatment actions. The drafting could have simply provided for cover for all injury suffered while a person undergoes treatment. But that course was not taken. Rather, boundaries were set out that have the effect of limiting the availability of cover for injury during treatment. A failure in the sense of omitting to take a step required by an objective standard is necessary. ...

Also, in Adlam, the Court of Appeal considered that the individual circumstances of the case are decisive. This confirms that there is no ‘‘one size fits all” solution. All that can be said generally are the conditions under which cover should be granted. And whether in an individual case this applies depends on the medical evidence in the individual circumstances.

In the case of treatment injury, the first distinction is to assess whether the medical treatment as such was considered to have caused injury, and if so, the next question is whether that treatment was a necessary part of the medical treatment overall (such as the incision during surgery), and whether the injury was an ordinary consequence and whether the injury was wholly or substantially the result of an existing health condition. At this point, things become difficult because medical treatment is usually sought to treat an underlying health condition.

In the situation of an injury due to a delay in diagnosis and treatment in a timely manner, the key question is whether a medical treatment which should have been given has not been given. This question must be decided on the medical evidence and only the medical indication can answer it.

Work related gradual process injury

This is one of the most complex injury types the statute knows. The reason is because principally, gradual process conditions - such as disease, wear and tear, degeneration, or signs of the aging process - are excluded from cover by law. The accident compensation scheme provides cover for traumatic injuries.

However, as the accident compensation law seeks to cover injuries caused by work (the accident compensation law originated in the workers compensation initially), injuries due to a gradual process condition which was caused or contributed to by work are included in cover. The relevant provision, section 30, includes a complex three tier test to determine the cause of an injury, and to draw a fine line between work related causes and non-work related causes. It is one of the most challenging legal grounds for cover and as in all cases medical evidence is required to demonstrate that the work played a critical part in the cause of the injury.

Injury caused by an accident vs pre-existing condition

This represents the statutory ‘default’ problem: what caused the injury? Was it the accident? or was the injury wholly or substantially the result of an existing disease, degeneration, wear and tear, or the aging process?

The distinction of causes is important. Why? Because section 26 determines that ACC must cover an injury which was caused by an accident; however, subsection (2) of section 26 prohibits ACC to cover any injury which was wholly or substantially the result of an existing condition. This is why ACC investigates the cause of an injury.

This is a medical question. The courts have repeatedly ruled that only injuries which are materially caused by an accident can attract cover. Vice versa, injuries, which occurred wholly or substantially due to degeneration, disease etc must not be covered.

The essential legal test is the so called ‘balance of probabilities’ test. This legal test on causation was established by the Court of Appeal in the judgement of ACC v Ambros [2007] NZCA 207. This was a treatment injury case and the Court of Appeal examined the matter of causation from all possible angles, and came to the conclusion, that it is impossible to find a cause with certainty but if the medical facts are sufficiently robust, then the judge or reviewer may draw a valid inference as to causation and accept a causal connection. This concept was recapitulated in the judgement of Aylward v ACC [2026] NZACC 35, where the judge determined -

“[46] In Ambros,1 the Court of Appeal envisaged the Court taking, if necessary, a robust and generous view of the evidence as to causation:

[65] The requirement for a plaintiff to prove causation on the balance of probabilities means that the plaintiff must show that the probability of causation is higher than 50 per cent. However, courts do not usually undertake accurate probabilistic calculations when evaluating whether causation has been proved. They proceed on their general impression of the sufficiency of the lay and scientific evidence to meet the required standard of proof ... The legal method looks to the presumptive inference which a sequence of events inspires in a person of common sense ...

[67] The different methodology used under the legal method means that a court’s assessment of causation can differ from the expert opinion and courts can infer causation in circumstances where the experts cannot. This has allowed the Court to draw robust inferences of causation in some cases of uncertainty -- see para [32] above. However, a court may only draw a valid inference based on facts supported by the evidence and not on the basis of supposition or conjecture ... Judges should ground their assessment of causation on their view of what constitutes the normal course of events, which should be based on the whole of the lay, medical, and statistical evidence, and not be limited to expert witness evidence ...:”

Each case is different as each person is different. No two people are the same, and no two accidents are the same. The medical evidence can only inform a case on an individual basis.