Irish motorists suspected of drink-driving are being automatically tested for traces of illegal drugs under a new Garda policy.
The move comes after figures showed the number of "drugged drivers" was on the increase and amid fears enforcement was less stringent.
Previously, a special test would be ordered only if it was thought drugs had impaired a driver's ability.
A road safety expert said today the drugs being tested for would reduce reaction times and make drivers less able to judge distance and speed.
But if the new campaign was to be successful, new laws would need to be introduced to allow the courts to punish drugged drivers, said Dr Denis Cusack, professor of legal medicine at University College Dublin.
"At present there is no limit set for drugs as there is for alcohol," he said. "It is still very much based on the opinion of an individual garda that a person was incapable of driving and under the influence of drugs.
"The penalties are not specified in the same way as alcohol - that reflects what is going on over much of Europe. At the moment if someone has a level of between 80 milligrams and 100mg of alcohol in their blood they are over the limit," Prof Cusack said.
"The penalty becomes more severe if it goes over 100mg and then again more severe if over 150mg. So we need to ask if there should be a stiffer penalty if someone tests positive for alcohol and another drug".
Studies in 1990, 1999 and 2001 showed an increase in the number of people driving with drugs in their bloodstream.
"Perhaps that is not surprising because there is an increase in the number of drugs used generally in society, particularly cannabis and ecstasy. These are among the drugs that are being seen in the tests," Prof Cusack said.
PA