Medical Negligence in New Zealand: When ACC Applies and When It Doesn’t

A surgeon removes the wrong kidney. An anaesthetist gives the wrong dose and causes permanent brain damage. A GP misses a cancer diagnosis that was obvious on the scans. In most countries, these situations lead to a medical negligence lawsuit. In New Zealand, they lead to an ACC claim. The ACC scheme abolished the right to sue for personal injury — including injuries caused by medical error — in exchange for no-fault compensation. But the system is not as simple as it appears, and many patients who were genuinely harmed by medical treatment never receive what they are entitled to because they do not know where to look.

ACC Treatment Injury: What It Covers

Part 3 of the Accident Compensation Act 2001 creates a specific category of covered injury called “treatment injury.” A treatment injury is a personal injury that is caused by treatment given by or at the direction of a registered health professional, and that is not a necessary part or ordinary consequence of the treatment.

Unpacking that definition is critical:

• “Caused by treatment”: There must be a causal link between the treatment and the harm. Not every bad outcome after treatment is a treatment injury — the treatment must have caused the injury.
• “Not a necessary part or ordinary consequence”: Known risks of treatment that are disclosed to the patient and occur as expected are not treatment injuries. If 1 in 50 patients who have knee surgery develop a blood clot — and this is a known, disclosed risk — a blood clot in that context is an ordinary consequence and not a treatment injury. If the blood clot was caused by a failure to properly anticoagulate the patient post-surgery, that may be a treatment injury.
• “Registered health professional”: Covers doctors, nurses, dentists, physiotherapists, midwives, pharmacists, and other registered health practitioners. It also covers people working under the direction of a registered practitioner.

What ACC Does NOT Cover After Medical Treatment

Several categories of harm from medical treatment fall outside ACC treatment injury cover:

The underlying condition itself. ACC does not cover the illness or disease you were being treated for. If you have cancer and the chemotherapy fails to cure it, your cancer is not a treatment injury.

Ordinary consequences of treatment. Known, disclosed risks that materialise are not covered. This is where ACC most frequently declines treatment injury claims — and it is also where the most disputes arise, because the line between “ordinary consequence” and “treatment injury” is not always obvious.

Failure to provide treatment. A decision not to treat — a GP who decides not to refer, a hospital that cancels an appointment — is generally not a treatment injury, because no treatment was given. This is a genuinely difficult gap in the system: pure diagnostic error or failure to treat may not be a “treatment injury” because no treatment causing injury occurred.

Pure economic loss. If a medical error results in you losing income, that loss is covered through ACC’s weekly compensation for incapacity — but pure economic loss without a physical injury is not covered.

How to Make an ACC Treatment Injury Claim

1. Identify that you may have a treatment injury. If something went wrong during or after medical treatment — unexpected harm, a complication that seems beyond the normal risk, evidence of an error — you may have a claim. Your treating doctor can refer you to ACC, or you can contact ACC directly.
2. Lodge a treatment injury claim with ACC. Your GP, specialist, or hospital can submit the claim form (ACC2152) on your behalf, or you can submit it yourself. Include as much detail as possible about what happened, when, and what harm resulted.
3. ACC investigates the claim. ACC will review your medical records and may seek an opinion from its own medical advisers. ACC has the right to obtain and review your full medical history relevant to the claim. The investigation period can take several months for complex treatment injury claims.
4. Receive ACC’s decision. ACC will decide whether your claim is covered. If accepted, you will receive cover for treatment costs, weekly compensation if you cannot work, and potentially a lump sum for permanent impairment. If declined, you have the right to request review within 3 months.
5. Challenge a decline if necessary. Treatment injury claims are frequently declined initially and successfully overturned on review, particularly where the causation question is contested. Obtain independent medical evidence from a specialist in the relevant field to support your review application.

The Health and Disability Commissioner: Complaints and Accountability

The ACC system compensates for harm — but it does not hold health professionals accountable, does not make findings about whether care was substandard, and does not require anyone to apologise. For patients who want accountability and not just compensation, the Health and Disability Commissioner Act 1994 creates a separate pathway.

The Health and Disability Commissioner (HDC) investigates complaints about health and disability service providers — doctors, nurses, hospitals, aged care facilities, and others. The HDC’s role is to determine whether a provider breached the Code of Health and Disability Services Consumers’ Rights (the Code). A finding of breach is not a criminal conviction, but it carries significant professional consequences and may result in referral to the Director of Proceedings for further action.

What the HDC Can Do

• Investigate complaints about any health or disability service provider
• Make findings on whether the Code was breached
• Recommend systemic improvements to health providers
• Refer cases to the Director of Proceedings, who may bring proceedings before the Human Rights Review Tribunal or refer to a professional disciplinary body
• Issue opinions that are public and named (when appropriate)

What the HDC Cannot Do

• Award compensation (except through the Director of Proceedings pathway)
• Impose criminal or civil penalties directly
• Discipline or deregister health professionals — that is the role of the Medical Council, Nursing Council, or other registration bodies

Time Limits for HDC Complaints

A complaint should generally be made to the HDC within 24 months of the event or when you became aware of it. The HDC has discretion to accept late complaints where there are good reasons, but earlier is better — evidence and recollections fade, and health providers’ records retention periods vary.

The Code of Health and Disability Services Consumers’ Rights

The Code — made under the Health and Disability Commissioner Act 1994 — sets out 10 rights that every health and disability service consumer in New Zealand has. Understanding these rights is essential for anyone who believes they received substandard care.

Right 4 (appropriate standards) and Right 6 (informed choice) are the most commonly breached rights that the HDC investigates. Right 4 covers cases of substandard clinical care. Right 6 covers situations where a patient was not properly informed of the risks of a procedure before consenting — which may overlap with both an HDC complaint and an ACC treatment injury claim.

Exemplary Damages: The Rare Civil Action That Survives

New Zealand’s ACC scheme bars most personal injury lawsuits — but it does not bar all civil claims arising from medical harm. One narrow but important exception: exemplary damages claims against health professionals for outrageous or reckless conduct.

Exemplary damages are not compensatory. They are awarded by courts to punish defendants for truly egregious behaviour — deliberate harm, conscious disregard for patient safety, or conduct so far below any reasonable standard that it warrants punishment beyond compensation. They are rare, difficult to obtain, and require expert evidence of conduct that crosses a very high threshold.

New Zealand courts have awarded exemplary damages in medical cases involving:

• Sexual abuse by a practitioner in the course of treatment
• Deliberate concealment of known errors from patients
• Knowingly substandard care provided in circumstances amounting to gross negligence

If you believe your situation may involve conduct at this level, legal advice from a barrister experienced in civil claims is essential. These are complex proceedings and the bar is genuinely high — but they do succeed in appropriate cases.

Professional Complaints: MCNZ, NZNO, and Other Bodies

Beyond ACC and the HDC, professional regulatory bodies can investigate and discipline health practitioners:

• Medical Council of New Zealand (MCNZ): Investigates concerns about doctors, including competence reviews and conduct hearings. Serious findings can result in suspension or deregistration.
• Nursing Council of New Zealand: Equivalent body for registered nurses and nurse practitioners.
• Pharmacy Council: Investigates pharmacist conduct.
• Dental Council: Investigates dentists and other oral health practitioners.
• Midwifery Council: Investigates midwives.

Professional complaints and HDC complaints can run in parallel. The HDC may refer cases to the relevant professional body, or you can complain directly to the professional body without going through the HDC. Professional body decisions are more likely to result in formal discipline — suspension, conditions on practice, or deregistration — than an HDC complaint alone.

When a Patient Dies: Rights of the Family

When a patient dies due to suspected medical error or substandard care, the family has several avenues:

ACC: A fatal treatment injury may entitle the deceased’s dependants to survivor grants, funeral grants, and weekly compensation for spouses and children. The ACC claim is made by the family as part of the estate process.

Coroner: If the death was unexpected, or if there is any question about whether medical care contributed to the death, a Coroner’s inquiry may be mandatory. Under the Coroners Act 2006, the Coroner can investigate the circumstances of death and make recommendations to prevent future deaths. The family can participate in the inquest and present evidence and questions.

HDC complaint: A family member can complain to the HDC on behalf of the deceased, even after death. The HDC has investigated and published findings in cases where patients died due to substandard care.

Professional complaint: Family members can also complain directly to the relevant professional body about the practitioners involved in the deceased’s care.

Frequently Asked Questions

What No One Tells You About Medical Harm in New Zealand

The ACC system was genuinely revolutionary when it was introduced in 1974. No-fault cover means that patients do not need to prove a doctor was negligent to receive compensation — they only need to show that the treatment caused the harm. In theory, this makes compensation faster and less adversarial than suing in court.

In practice, it also means that the health professional who caused the harm faces no financial consequence. The cost of the error falls on ACC — and ultimately on levies paid by employers, employees, and car owners across New Zealand. The doctor who amputated the wrong limb continues to practise. There is no lawsuit, no damages award, no financial accountability for the practitioner.

This is why the HDC pathway matters as much as it does. For patients who want someone to be accountable — not just for money, but for what happened and why — the HDC and professional complaints systems are the tools available in New Zealand. They are imperfect, slower than many patients expect, and their outcomes are not always satisfying. But they are real, and they have resulted in practitioners being deregistered, practices being changed, and systemic problems in hospitals being exposed to public scrutiny.

Knowing which pathway to use — and when to use both — is what a medical lawyer can help you determine.

Sources and Legislation

• Accident Compensation Act 2001 (Part 3, ss 32–35, treatment injury) — New Zealand Legislation
• Health and Disability Commissioner Act 1994 — New Zealand Legislation
• Coroners Act 2006 — New Zealand Legislation
• Code of Health and Disability Services Consumers’ Rights — HDC (hdc.org.nz)
• Treatment injury cover — ACC (acc.co.nz)
• Concerns and complaints — Medical Council of New Zealand