People who drive after taking illegal drugs could be banned for a year and fined up to £5,000 - even if there is no evidence that their driving was impaired.

The Government is considering a new offence under which police would need to prove only that drivers had taken a banned drug.

As traces of drugs can stay in the body for several weeks, drivers could find themselves convicted of the new offence long after taking a substance.

The DfT, however, said there would be safeguards in any new drug driving offence to prevent drivers from being prosecuted for having "inactive metabolites of cannabis in their system".

There are very few prosecutions for drug-driving under the current law because it requires proof both that a drug was taken and that the driver was impaired by it.

The Home Office is preparing to approve handheld devices that can be used to detect a range of drugs from a saliva sample given at the roadside.

Philips, the Dutch electronics company, announced yesterday that it will start deliveries to police next year of a machine that detects five different drug groups, including cocaine, heroin and cannabis, in just 90 seconds from a single saliva sample.

A Department for Transport consultation paper said the problem of drug driving was “serious and increasing” and largely going unpunished. In the past decade, there has been a six-fold increase in the proportion of road deaths in which the victim was found to have taken cannabis.

As a first step, the Government intends to strengthen police powers to require a suspected drug driver to give a biological sample.

In addition, the document says: “A driver could be convicted of a new offence if an appropriate test showed an illegal drug... our ultimate aim would be to treat in this way any illegal drug capable of impairing driving.”

Rob Gifford, director of the Parliamentary Advisory Council for Transport Safety, said: “This is a very difficult area for legislation because you cannot say that the joint a person smoked four weeks ago caused him to have an accident today.

The document concludes: “We accept that much more work will be needed to develop a workable solution to a complex problem.”

It confirms, as The Times revealed last month, that ministers have backed away from a previous commitment to lower the drink-driving limit to the level that is enforced in most of the rest of Europe.

Jim Fitzpatrick, the Road Safety Minister, said: “We are seeking views and evidence on the question of reducing the legal alcohol limit, on which we have a completely open mind.”

However, the DfT plans to increase enforcement of the existing limit by allowing police to set up roadblocks to carry out random breath testing. Drivers will also lose the right to play for time by requesting a second test of a blood sample taken by a doctor.

The Government's retreat on lowering the limit was condemned by the family of two boys killed by exPlymouth goalkeeper Luke McCormick in a crash on the M6.

Philip and Amanda Peak lost their sons Arron, 10, and Ben, eight, after McCormick's Range Rover hit their people carrier on the motorway near Stoke-on-Trent in June. McCormick is serving a seven-year sentence after admitting causing death by dangerous driving and drink-driving.

Mrs Peak said: “It's Christmas coming up and you know all those people are going to go out, get drunk, get in their car the next morning and not think of the consequences they are going to cause.”

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