A guilt-ridden tourist who killed two men in a car crash tried to pay back ACC for his medical costs, but was told it couldn't take his money.
US heart surgeon Dr Kenneth Wolnak, 63, whose careless driving killed two men in Nelson in February, offered to pay ACC for his medical bill, but his offer was rejected for legal reasons.
ACC said it could not take money from any individual, regardless of whether the payment was voluntary.
"Our funding mechanisms are provided by statute, and therefore any other funding is considered beyond our legal role," an ACC spokesperson said.
Don Rennie, who helped to set up ACC in 1974 and is now the convenor of the Law Society's ACC arm, said that was absurd.
"There should be some way that that money can be repatriated back to New Zealand. I think it's ridiculous that they don't have some system where people who feel conscience-bound to pay can pay it back," Mr Rennie said.
Data given to Checkpoint with John Campbell shows overseas visitors filed 10,558 ACC claims last year - nearly 30 a day - at a cost of $5.1 million.
Three years earlier in 2013, those numbers were less than half of that: 4647 claims at a cost of $2.4m.
Mr Rennie said he believed ACC could legally accept Dr Wolnak's money if it wanted.
"I'm not aware of anything in the legislation that says ACC can't receive compensation which is voluntary returned," he said.
Another leading ACC law expert, Warren Forster, agreed.
"There's nothing stopping ACC receiving [Mr Wolnak's] payment," he said.
But ACC Minister Michael Woodhouse said he did not want ACC to accept Mr Wolnak's money, as it would signal a move towards a system where tourists pay.
"If insurers from overseas were required to pay out from New Zealand-based accidents, they would look for a remedy, they would look for the person who was at fault and seek to claim money back from them," Mr Woodhouse said.
"If I was at fault in an accident with a foreign driver, and their insurance company paid out, then there's no doubt they'd come to me for liability... and I don't think that's where we want to go."
Mr Forster said the total cost of overseas visitors' healthcare could be much higher than the $5.1m cost to ACC, because acute hospital care, for example emergency departments, might not be recorded on an individual basis.
But he said tourists might pay for their own ACC costs through the 6.9 cent per litre fuel levy.
"It could be that through fuel and motor vehicle levies that $5m is collected already, they could be making $20m profit on top of that," Mr Forster said.
ACT party leader David Seymour wants ACC to be scrapped entirely, or at the very least updated.
"In 1974 when ACC was set up, we were an insular country with not a lot of coming and going. Today we're a highly globalised country and we need to modernise, we need a system where people outside the country can make a contribution for the risks that they take," Mr Seymour said.
If current trends continue, overseas visitors could cost ACC around $10m a year by 2020.
Overall, ACC paid out nearly two million claims last year, at a cost of $3.5bn.