Motorists who cause death by dangerous driving could face up to 14 years in prison under new measures.
David Blunkett says new measures will favour victims of crime
The new maximum term, up from 10 years, is aimed at clamping down on drivers who cause death, be it through driving while drunk or on drugs or "joyriding".
Home Secretary David Blunkett said: "Dangerous drivers who kill should be
But some road safety campaigners have expressed scepticism about the move, which became effective on Friday.
The government has described the changes, first unveiled last year in the Criminal Justice Act 2003, as "the most significant overhaul of the criminal justice system in a generation".
Mr Blunkett said: "This is just one of the many reforms we are delivering under the Criminal Justice Act 2003 which will modernise and rebalance the criminal justice system in favour of victims, witnesses and communities."
A spokesman for the road safety charity, Brake, said: "We are extremely pleased that the Home Office has come out with an appropriate sentence for this appalling type of offence."
Kevin Clinton, head of road safety at the Royal Society for the Prevention of Accidents, said: "Deaths caused by dangerous driving are every bit as tragic and criminal as murder. It is quite right that the courts should reflect this."
But some relatives of people who have died in road accidents are among critics of the move.
George Galli-Atkinson, whose 16-year-old daughter was killed after a driver mounted a pavement and struck her, said he was "very sceptical" the increase would act as any kind of deterrent.
Mr Galli-Atkinson, a spokesman for the Roadpeace support group for road crash victims, said: "Sentences should be tackled from the other end.
"What we need to see is not 14 year maximum sentences but two year minimum sentences for those found guilty of death by dangerous driving."
John Sparrow, 64, secretary of The Campaign Against Drinking and Driving (CADD), said: "I've never heard of anyone getting the full ten years for causing death by dangerous driving... I don't think the 14 year maximum will be used any more than the 10 year one is at the moment."
But Chief Superintendent Bob Pattison, chair of the Northumbria Police Superintendents' Association, said: "This is a welcomed move. It does send out a very clear message and should act as a deterrent.
But Mr Pattison, a vocal campaigner for tougher jail sentences for dangerous drivers, added: " The problem at the moment is that the 10 year rule doesn't
seem to be having that effect."
He said courts should be able to impose life sentences if there were aggravating circumstances like driving under the influence of drink or drugs.