Eluana Englaro, 37, has been in a vegetative state since a serious car accident in January 1992, when she was 19.
Her father, Beppino Englaro, asked for the right to remove Eluana's feeding tube in 1999, sparking a nationwide debate about the right to die. The Roman Catholic Church, which has significant influence in the country, strongly opposed letting Eluana die.
The judge said the decision was based on the woman's own wish, who clearly stated before the accident that she would rather die than live in a vegetative state.
With the highest court's approval, Englaro's feeding tube will soon be removed and she will die of dehydration in two weeks.
Although euthanasia is illegal in Italy, a patient is entitled to refuse treatment, even if it leads to his or her death.
In 2006, Dr. Mario Riccio was arrested after he removed a respirator on the request of a terminally ill Italian man. Piergiorgio Welby, who suffered from muscular dystrophy and needed a respirator to keep him alive, had repeatedly asked to be taken off the breathing equipment.
The doctor was released later on the grounds that Welby's case was an example of refusing treatment, not euthanasia.