Several relatives of Nicolas Bonnemaison's patients had testified on his behalf.
The case had drawn nationwide attention and emotion amid mounting calls in France to legalise euthanasia. It is currently legal in the Netherlands, Belgium and Luxembourg.
Today's decision comes the same day Britain's Supreme Court said that a ban on assisted suicide was incompatible with human rights.
The British decision was unexpectedly far-reaching. Although it dismissed the appeal from two severely disabled men who argued the law should be changed to allow doctors to legally kill them, the ruling suggested that Parliament change the law to be in line with human rights guarantees.
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France's top administrative court yesterday said doctors could withhold food and hydration for Vincent Lambert, saying he had made his wishes clear before the car accident six years ago that left him hospitalised.
That decision was overruled hours later by the European Court of Human Rights in a highly unusual late-night decision. It ordered France to continue treatment until it can examine the case.
"He is not sick, he is not at the end of his life, he is not suffering," Jean Paillot, a lawyer for Lambert's parents, told BFM television today. "From our perspective, there is no reason to stop feeding or hydrating him."
The Lambert case has echoes of the legal fight over Terri Schiavo, a Florida woman who suffered brain damage in 1990 when her heart stopped, and she entered what doctors refer to as a "persistent vegetative state," or prolonged coma.
She died in 2005 after her husband won a protracted court case with Schiavo's parents to have her feeding tube.
One of the men, Paul Lamb, is paralysed following a car accident. The other, Tony Nicklinson, died of pneumonia in 2012, but the case has been taken over by his widow.