Doctors at a hospital in the U.K. acted within the law when they allowed a young woman to kill herself because she told them she wanted to die, a coroner has ruled.

It is believed to be the first time a so-called "living will" has been used in the country to legally aid someone's suicide.

Kerrie Wooltorton, who suffered depression over an inability to have children, was rushed to hospital by ambulance from her apartment in Norwich, England after swallowing antifreeze fluid.

But before lapsing into unconsciousness, the 26-year-old gave doctors the legally-binding letter, saying she did not want to be saved.

Click here to read Kerrie Wooltorton's 'living will'

Known in medical terms as an advance directive, living wills are designed to guide doctors on treatment for patients after they become incapable of decisions or terminally ill — not for suicides.

An inquest into Wooltorton's death found she had been treated at mental health units and had swallowed lethal anti-freeze up to nine times in the preceding 12 months — but each time doctors had saved her.

Wooltorton wrote her living will on September 15, 2007, explaining that she was "100 percent aware of the consequences" of taking poison and that she did not want treatment.

Three days later she swallowed antifreeze and called the emergency services before being taken to Norfolk and Norwich University Hospital where she told staff of her wishes and gave them the letter.

It said that if she called for an ambulance it was not because she wanted lifesaving treatment but because she did not want to die in her home, alone or in pain.

Wooltorton died in a hospital bed the following day, but her family believes she should have been saved.

"She refused such treatment in full knowledge of the consequences and died as a result," Coroner William Armstrong said. "Any treatment...in the absence of her consent would have been unlawful."

Dr Alexander Heaton, the hospital's consultant renal physician, was asked what would have happened if he intervened.

"I would've been breaking the law and I wasn't worried about her suing me, but I think she would have asked, 'What do I have to do to tell you what my wishes are?',” he said.

"It's a horrible thing to have to do, but I felt I had no alternative but to go with her wishes. Nobody wants to let a young lady die."

Click here to read more and see photos of Kerrie from Sky News.