New technology that can detect drug-driving is being developed for use by UK police.
The government is understood to be asking companies to design a UK-specific “drugalyzer” that would detect banned substances.
If the driver proves positive they will be taken to a police station for a doctor to take a blood sample, which would then be used in court.
Drugs that could be detected by the technology would include cocaine, ecstasy and cannabis.
Other countries in Europe already have such systems and ministers are keen to bring in tough measures to stop drug-driving.
Within the next few months the Home Office is expected to draw up detailed specifications with the Forensic Science Service, in the hope that roadside tests will be introduced within the next five years.
"At present, we know that a number of drivers are getting behind the wheel while under the influence of illegal drugs," said Robert Gifford, executive director of the Parliamentary Advisory Council for Transport Safety.
"Effective devices would help us to get a better indication of both the scale of drug-driving and the options available to us for tackling it."