The NHS is having the "life squeezed out of it" by cuts imposed because of deficits, says the UK's nurse leader.
Dr Carter warned of tough times
Dr Peter Carter, general secretary of the Royal College of Nursing, congratulated ministers for tripling the health budget since 1997.
But he warned the progress made was at risk of being reversed as wards are closed, jobs lost and services slashed.
Nurses called for the law to be changed to introduced guaranteed nurse/patient ratios as a way of preventing cuts.
Speaking at the RCN's annual conference in Harrogate, Lothian nurse Geoff Earl said evidence had shown death rates increased by a third if the number of patients per nurse increased from four to eight.
"The lower the ratio the lower the rates of urinary tract infection and pneumonia," he said.
"It also improves recruitment and retention, reduces the use of agency staff and leads to less staff sickness. So it also makes financial sense - in the long term."
David Dawes, part of the RCN's body for nurses in senior management, said he supported the move as it would make many of the recent cuts - the RCN estimates over 22,000 post have been lost in the last 18 months - illegal.
And Lisa Leicester, a community mental health nurse from Gloucestershire, added: "Lets ensure appropriate staffing levels but also appropriately qualified nurses."
Nurses voted to pass a motion calling for new legislation to ensure appropriate staffing levels.
Ratios would vary depending the type of care a patient was receiving but could mean in some specialities (did not specify which one) one-to-one care would be guaranteed.
But Howard Catton, head of policy at the RCN, said: "The problem with minimum ratios is that they becomes maximums and that takes away from professional judgement. And if minimums can't be met, wards are closed."
The debate came after the RCN's new leader set out the "tough" times the NHS was facing.
The former NHS trust chief executive, who took up the post in January, said: "Training budgets are being raided and public health programmes are being targeted.
"We've got workloads gong through the roof as jobs are lost and vacancies frozen."
He said the Labour government deserved credit for increasing funding, which has increased the workforce of nurses and doctors.
But he added: "The situation is so serious that the progress we've made could soon be reversed or, sadly, lost altogether."
NHS trusts are making cuts in a bid to balance their books after racking up over £500m of deficits last year.
Alluding to recent press reports, Dr Carter said it had got so bad that nurses were being asked to work for nothing and cutting down on the use of lightbulbs.
He also strongly criticised this year's 2.5% pay rise for nurses, describing the award as "shameful".
Commenting on the fact the RCN has not invited any politician to congress this year, he said: "It was pointless bringing someone from government in because of how badly they have treated nurses and other health workers."