The Gardai are to start roadside testing for drugs. Many patients in Ireland are on drugs such as opiates and benzodiazepines. These drugs, amongst others, have the potential to cause sedation and impair driving. Obviously, if someone does feel sedated or impaired, they should not drive until they feel fit to do so. However, this does not mean that all patients on such drugs are impaired and unfit to do so. Over time, tolerance to such drugs, particularly when taken at modest doses, may develop.
There is to be a clinical test at the roadside to determine whether or not an individual is impaired or not.
Here is a link to a RSA leaflet on the situation: http://www.garda.ie/Documents/User/RSA%20Medicine%20information%20leaflet.pdf
I predict that this legislation and the proving of impairment will be difficult to enforce and may be subject to vigorous challenge by defence lawyers throughout the land.