The rising cost of litigation is threatening the financial health of the NHS in England, auditors are warning.
The National Audit Office says the bill for clinical negligence has quadrupled in the last 10 years, reaching nearly £1.6bn last year.
It is urging the government to do more to curb the costs.
But ministers say they are taking steps, pointing out moves have been made to limit lawyer fees as well as a swifter resolution for birth injuries.
The latter tends to attract the highest damages awards because of the lifelong care that is needed in the worst cases.
But the NAO said on their own these measures would still not be enough.
It said some trusts were already spending 4% of their income on clinical negligence, which was proving too much.
And it said this could become the norm – with annual costs expected to top £3bn by 2020-21.
It pointed out there was no evidence more mistakes were being made or care was getting less safe.
Instead, the NAO said the rising costs were related to higher damages awards, higher lawyer fees and more claims.
NAO head Amyas Morse said litigation was a “significant” cost placing pressure on an “already stretched system”.
And Niall Dickson of the NHS Confederation said: “We cannot go on like this. This rising tide of litigation is draining the NHS of resources and must be urgently addressed.”
A Department of Health spokesman said the steps being taken would help.
But he added “there is still more to do”, adding a new strategy would be developed in the future.