People who suffer treatment injuries could have a better chance of getting ACC cover after a landmark High Court ruling.
In the decision released on Friday, Judge Peter Churchman has dismissed two appeals by ACC against district court decisions in favour of a woman who had suffered a stroke during brain surgery and another who ended up incontinent and numb down one leg after an operation on her spine.
A lawyer for one of the women, Brittany Peck, says ACC had attempted to decline cover on the basis the injuries were "an ordinary consequence" of treatment.
"What this decision helps us do is show that this shouldn't be the case, and the Corporation should be taking a more generous approach when looking at these types of treatment injury cases."
The Corporation was of the view the district court had been overly generous in giving people cover in situations that occurred in 20 or 30 percent of cases.
The High Court however found that in order for a consequence to be "ordinary", it should have a 50 percent or greater chance of occurring.
Ms Peck said the ruling could open the way for others to appeal ACC decisions.
It upheld Parliament's original intention in amending the ACC legislation in 2005 to replace "medical misadventure" with "treatment injuries", she said.
"The idea was to expand cover and to make it easier for people who experience unintended consequences of their treatment to get cover so they can come within the realms of the ACC scheme, to get treated and rehabilitated."
The judge however rejected an appeal by a third woman, who suffered nerve damage after surgery, because she did not provide any evidence that her treatment injury was something other than an ordinary consequence.