The woman, in her 60s, was told by medics in central England to have her leg amputated after what started as a superficial ulcer on her right foot turned gangrenous, a court heard.
Her foot 'came off' in January, but the patient, who has suffered from paranoid schizophrenia, refused medical advice to have her leg amputated.
Lawyers representing the Heart of England NHS Foundation Trust rushed to the Court of Protection in London in a bid to win permission to carry out the op without the woman's agreement, the Birmingham Mail reported.
"The freedom to choose for oneself is a part of what it means to be human," the judge said.