The NHS in England faces paying out £4.3bn in legal fees to settle outstanding claims of clinical negligence, the BBC has learned through a Freedom of Information request.
Each year the NHS receives more than 10,000 new claims for compensation.
This figure includes all current unsettled claims and projected estimates of ones in the future.
The Department of Health has pledged to tackle "the unsustainable rise in the cost of clinical negligence".
Estimates published last year put the total cost of outstanding compensation claims at £83bn.
NHS England's total budget in 2018-19 was £129bn.
The Association of Personal Injuries Lawyers believes the cost is driven by failures in patient safety.
Doctors represented by the Medical Defence Union, which supports doctors at risk of litigation, are calling for "a fundamental" reform of the current system.
Hayden Nguyen was born in August 2016. Six days later he died in the Chelsea and Westminster Hospital in London. His heart failed after it was attacked by a virus.
Initially Hayden's parents did not know what had happened to him. In the face of official silence and in a bid to get answers they took legal action against the hospital.
After three years the trust admitted liability for a failure to adequately treat his condition. The Nguyens received a small amount of compensation and their legal fees were met by the trust.
His father Thong said: "It was every parent's worst nightmare. We had to sit there and watch our son slowly die in front of our eyes.
"I haven't really thought about it as suing the NHS. I thought about it as fighting for a voice for Hayden, fighting for acknowledgement of his life, and his rights."
His mother Alex said: "It has been four years so far of trauma after trauma."
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