Gardaí will be able to carry out roadside tests on drivers for narcotics under new legislation announced on Tuesday.

Drivers caught with any trace of cannabis, cocaine, or heroin in their system will face a €5,000 fine or imprisonment of up to six months under the Road Traffic Bill 2015.

There are also provisions for the arrest of those caught with a high volume of codeine in their system, but an impairment test must be carried out.

At the moment, motorists can only be prosecuted if caught driving recklessly as a result of drug-taking. However the fresh legislation would allow gardaí to pull drivers and conduct a saliva test, followed by a blood test.

Minister for Transport Paschal Donohoe said any trace of illicit drugs in the system will be punishable.

“What we are now doing is bringing into line our body of law in road law in relation to alcohol to make that completely consistent now with drug testing,” he said.

The Minister admitted that those who have the drugs in their system for more than a week or two could be subject to the new legislation.

He said the focus on drug-driving will not result in neglecting the effort to tackle drink-driving.

“Driving under the influence of alcohol remains one of the most dangerous factors on our roads.”

The legislation will also allow for a lower speed limit of 20km/h to be implemented in residential areas. But it is not mandatory as has been requested by road-safety campaigners.

Residential areas

Mr Donohoe said local authorities had been extremely successful in lowering the limit without legislation.

“I am making it very clear my expectation that in residential estates in which there are large numbers of young families and which do have busy roads within them . . . a lower speed limit is appropriate for them.”

He added it was “evident that the best way to have is to have them enforced is by allowing officials in local authorities and local councillors to implement the speed limit that is appropriate in consultation with those who live in those estates”.

There will also be provisions for the recognition of driver disqualifications between Ireland and the United Kingdom.

Mr Donohoe said the legislation will be passed by the middle of 2016.

Parc, a road safety group, welcomed the new provisions but urged the Minister to ensure the legislation is enacted as soon as possible.

"The time delay of six months to enact the legislation will allow the stakeholders to get prepared. It will give time for the provision of IT systems that talk to each other, linking the gardaí, transport, Courts Service and Road Safety Authority, " said spokeswoman Susan Gray.

“What we don’t want are excuses followed by another long delay that costs more unnecessary lifelong suffering and death.”