American-style roadside co-ordination tests for those suspected of driving under the influence of drink come into force today.

Motorists suspected of taking drugs before getting behind the wheel can be asked to take a 5-step test - which tests drivers' balance, co-ordination and focus.

Blood tests for drivers who have been injured in crashes are also coming into use.

Liz O'Donnell, Chief Executive of The Road Safety Authority, said many drivers are under the impression they drive better when they are under the influence of drugs, and this is “a lethal fallacy”.

“Some people actually delude themselves into thinking they’re better drivers because they’re stoned, they think their driving is better because they’re using drugs,” she said. “Of course this is a complete lethal fallacy.”

The new tests, which you can see an example of in the video below, will give gardai powers totest drivers they might be suspicious of.

“From now on people should be aware that they can be stopped on the roadside just like for alcohol and they can be apprehended and arrested and they can be disqualified from driving,” Ms O’Donnell said.