Police Constable Paul Briggs, 43, suffered a brain injury in a crash while he was working for Merseyside Police in July last year.
His wife Lindsey had told a Court of Protection treatment should be stopped "given his previously expressed wishes" and he should be allowed to die, the BBC reported.
Doctors at the Walton Centre had opposed the withdrawal of treatment to the Gulf War veteran.
They had advised the judge to be cautious and a specialist said there was "potential" for Briggs to emerge from a minimally conscious state.
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Mrs Briggs said: "The court case was the hardest thing we have ever had to do but we did it for Paul, to honour his wishes."
The Official Solicitor is to seek leave to appeal against Tuesday's decision at the Court of Appeal.
Normally, patients at the centre of Court of Protection litigation are not identified because judges aim to protect their privacy, ITV reported.
But Briggs' accident was widely reported and no-one involved in the litigation has asked for him to be anonymised so the judge allowed him to be named, it said.