Garda Sergeants and Inspectors say it may be some time before roadside drug testing is actually carried out by the force, despite the announcement that it can commence from tomorrow.
The Road Traffic Act comes into force tomorrow, but the AGSI says its members haven't received training in using drug testing devices.
Senior Gardaí say the traffic corps have been fully trained in the use of the machines, and that will be rolled out to all officers in the coming weeks.
General Secretary of the AGSI John Jacob says the public may have been given the wrong impression.
"They should have cautioned people that the Gardaí at this point in time, from what I can understand from my colleagues here... that we don't have the capacity at this point in time to deliver this service."