I had set aside the Commons Hansard of 28 January to pore over the second-reading debate on Ann Winterton's Medical Treatment (Prevention of Euthanasia) Bill in a quiet moment. So it came as a shock to realise that it had led Liberal Democrat MP-GP Peter Brand to be investigated by Hampshire police on suspicion of murder.

An admirable MP in many ways, Mrs Winterton is married to her constituency neighbour, Nicholas Winterton MP, formerly the pro-NHS Tory chair of the Commons health select committee. Honest and independent-minded, the Wintertons are model backbenchers of the right-wing variety. Ann's video exhibition of pornography in the Commons a few years back included footage of the kind I had not seen and do not wish to see again.

But is she right on this one? Or is Dr Brand? The bill got its second reading by a thumping 113 votes to two (plus two tellers) after an enthralling debate, which included the nowfamous confession by the Isle of Wight MP.

He had owned up to 'an active withdrawal of treatment for a condition that might have responded to treatment' - in the case of a two-year-old boy suffering such agonies from leukaemia that his parents begged Brand to stop.

This was in 1972, I hasten to add.

But these are sensitive times, when newspapers are full of moral panic of one kind or another: gay sex, voluntary amputations, homicidal doctors, and disquieting cases of patients, young and old, dying from the effects of withdrawal - key word - of artificially administered food and water.

That is 'the slippery slope of euthanasia', as critics put it, because the distress of such deaths will soon create a climate where patients' families will opt for some 'help' being given.

The Winterton camp believes that throughout the 1990s the British Medical Association, the Law Commission and successive governments have been on that slippery slope, especially the BMA's 1999 guidelines.

Dr Brand probably did not help himself by saying that he is 'a multiple murderer', as the bill is currently drafted, insofar as it renders unlaw - ful acts of both commission and (very important) omission by a doctor 'if his purpose or one of his purposes in so doing is to hasten or otherwise cause the death of a patient'.

His remarks prompted a lady in Weybridge to start badgering the police and the media to take steps against him - steps which he first read about in the newspapers. When Brand rang in the police wouldn't tell him if he is being investigated. Apparently they don't, but they did feel able to tell the media, he notes with gentle irony.

All the same, Brand is unrepentant.

He voted against Labour MP Joe Ashton's 1997 Doctor-Assisted Dying Bill and has some sympathy with efforts to clarify the impact of the Law Lords' ruling in the Tony Bland case, where the Hillsborough stadium victim's life was ended by the withdrawal of artificial feeding (treatment, not care, the judges agreed).

What was striking about the debate was that three medical MPs, Brand and his Lib Dem colleagues Jenny Tonge and Evan Harris, joined him in warning that the bill's terms are drawn dangerously wide, concentrating on the doctor's 'purpose' (doctors do not always know what will happen next), not the patient's need.

Against them were arrayed Labour, Tory and Unionist MPs who had either strong religious conviction or (this was very striking) direct experience of a family or constituency crisis, a dying mother or grandchild who had died - or lived, in Claire CurtisThomas's 'vegetative' mum's case - because of medical decisions.

They found Brand's remarks disturbing, chilling, offensive. Slightly Nazi, according to Labour's effortlessly offensive George Galloway, who has not trusted doctors since his father's death, a stroke complicated by pneumonia which was not treated after the first 'vegetative' week.

I should add that Yvette Cooper, the duty minister, is obviously unhappy with the sweeping way the bill is drafted. Passions are aroused. Battle now moves to detailed analysis on Wednesdays in a standing committee dominated, I am told, by Wintertonian forces. But Ms Cooper's veto hovers over it.