Medical mishaps and ACC reform: where to from here?

A leading expert is visiting New Zealand to examine how well ACC’s approach to medical harm delivers outcomes for injured patients, nearly two decades after major reforms.

Professor Michelle Mello (Stanford Law School and Stanford School of Medicine) has a long-standing connection to New Zealand; among her two decades of research on medical injury are studies of the ACC system here and its relevance for efforts to reform medical liability in the US.

Her lecture, on 10 March 2026 at the University of Auckland, will explore developments in New Zealand’s ACC cover for medical treatment injury alongside developments in medical and vaccine liability law in the US.

“ACC is one of the most fascinating policy experiments in the world,” says Mello, “and it has much to teach us.”

In 2005, Parliament amended the Accident Compensation Act to replace cover for ‘medical misadventure’ with cover for ‘treatment injury’. The reform aimed to provide a more systemic approach to medical accidents, improve fairness and reduce claims processing times by reviewing treatment injury claims on a no-fault basis.

“The less we make it about whose fault it was, the more people are willing to talk and learn,” says Mello. “But not assigning fault can undercut incentives for improvement, too.”

Treatment-injury cover is ACC’s system for supporting people who are unintentionally harmed by medical treatment, for example, through misdiagnosis, surgical complication, or medication error. Patients don’t need to prove anyone was at fault, and ACC provides support such as treatment costs, rehabilitation, and income assistance.

Mello says it’s time to review the reform's implications for patients, providers, and the health system, and she will be discussing whether no-fault liability can provide sufficient accountability for injuries to patients.

She will also discuss whether it can create sufficient impetus to drive change in the conditions that lead to treatment injuries across the healthcare system, as well as what’s been learned in New Zealand and other countries about patients’ needs following medical injury.

One of the greatest conundrums, says Mello, is how to connect injury compensation systems with patient safety improvement.

Professor Jaime King, the John and Marylyn Mayo Chair in Health Law at the University of Auckland, says patient safety should be of the utmost importance in any health system, but especially within New Zealand, as the public pays for the original treatment, follow-up care, and ACC support.

“Every error that can be averted benefits not only the immediate patient and their families, but the whole of society.”

Mello’s lecture honours the late Sir Owen Woodhouse, architect of New Zealand’s ACC scheme.