Claims that laws introducing so-called "living wills" would legalise euthanasia by the back door have been rejected by the government.
It came in a debate on the Mental Capacity Bill which lets people set out in advance a wish to refuse treatment if they become mentally incapacitated.
Constitutional affairs minister David Lammy said there were strong safeguards and euthanasia remained a criminal act.
MPs voted to give the Bill its second reading by 326 to 62.
Batting off concern from all sides, Mr Lammy insisted the Bill did not alter the "fundamental arrangements".
"What it does do is make clear that any decision must be made in the best
interests of the person that lacks capacity."
 |
The Bill says each decision or act must be based on the best interests of the individual
|
Mr Lammy also pointed out that the Catholic Church, with whom the government had worked over the Bill's wording, had accepted it would not legalise euthanasia.
But cross-party fears about the effects of the legislation were voiced by a
number of senior MPs including former Tory leader Iain Duncan Smith.
He suggested the Bill had "carefully left open" the issue of whether someone in a persistent vegetative state would be covered by the legislation.
Former Conservative minister Ann Widdecombe said: "Will you categorically assure the House, with no ifs and buts, that treatment does not include provision of assisted food and fluid?"
Opening the second reading debate, Mr Lammy said that up to 2m people were mentally incapacitated because of dementia, severe learning disabilities, mental illness or head injuries.
'Real risks'
He pointed out that the Bill had been closely scrutinised by a committee of MPs and was strengthened as a result.
"It is a Bill about the rights of the individual person; it starts by saying that individuals should be assumed capable of making decisions and helped to
make them.
"If they cannot, the Bill says each decision or act must be based on the best interests of the individual."
But Labour's Jim Dobbin, chairman of the all-party pro-life group, warned: "Government assurances about the practical implications of this Bill don't go
far enough.
"The risks of abuse are very real."
'Absolutely wrong'
Another Labour MP Claire Curtis-Thomas said her paralysed mother had drawn up a legally binding directive after a stroke saying that she should not be revived in similar circumstances again.
But after another five stroke years later her mother communicated
through blinking that she did not want to be starved to death.
"It is almost impossible for us to know what we would be like under any given
circumstances until those circumstances have arisen.
"It is absolutely wrong of us, the able bodied and the able minded, to take
that right away from an individual," she said.