Motorists suspected of driving under the influence of drugs may be tested by gardaí at the roadside under new legislation. 

Drug driving is a factor in one in ten fatal crashes in Ireland.

Last December, the Oireachtas passed the Road Traffic Act 2016, which paved the way for the drug testing of drivers' saliva both in garda stations and by the roadside.

Drivers can now be tested for four types of drugs - cannabis, cocaine, opiates like morphine and heroin and benzodiazepines such as valium, sleeping tablets and certain anti-anxiety medication.

Levels will be set for cannabis, cocaine and heroin, which will mean if drivers go over those limits gardaí will not have to prove impairment.

The new legislation means a garda will not have to prove a driver is impaired when it comes to certain level of cannabis, cocaine and heroin.

This is in line with how alcohol has been treated in Irish road traffic law.

However, a different approach will be taken for prescribed or over the counter drugs. It will only be an offence if there is a confirmed presence of these drugs with impairment.

Drivers who, for example, are prescribed to take medical cannabinoids will be able to carry notes of exemption.

The new device is called the Dräger DrugTest 5000. It is a portable device and about the size of a computer hard-drive.

A drivers' saliva will be tested with a single-use swab. The sample will then be tested to determine if drugs are present. The result will be produced within around eight minutes.

If a person is found to have drugs present, they will be arrested and brought back to a garda station where a blood sample will be taken.

There will be 86 drug screening devices located in garda stations nationally, 50 more will be available for use at the roadside.

Gardaí have been in training on how to use the new kits and other drugs could be added to the tests in the future.

The Medical Bureau of Road Safety found that out of the 9,734 specimens of blood and urine tested for the presence of a drug or drugs between the years 2009-2015, 6,232 or 64%, tested positive.

Assistant Garda Commissioner Michael Finn said drug-driving is one of the most dangerous offences that can be committed on our roads.

MBRS Director Professor Denis Cusack said drivers with medical conditions "should continue to take their prescribed medications in accordance with healthcare advice and medical fitness-to-drive guidelines".

He said as long as those medicines do not impair driving, drivers have nothing to be concerned about. 

However, these people are being warned that if such drivers are impaired, they will face the same sanctions as other drivers under existing drug driving legislation and can be prosecuted.

Drivers found abusing drugs such as cannabis, cocaine, or heroin face a minimum disqualification of one year, a fine of up to €5,000 and up to six months in prison.

The disqualification rises to four years if a driver is found to have drugs in their body and their driving is impaired.