The new Road Traffic Act, which allows gardaí to randomly stop and breathalyse drivers, came into effect last night.
Anyone caught using a mobile phone behind the wheel will face prosecution under the extensive new powers.
Checkpoints were set up throughout the country overnight.
The act also provides for the introduction of privatised speed cameras and any foreign vehicles that are not insured will now be impounded by gardaí.
Increased garda checkpoints are expected around the country over the weekend, including outside pubs in an attempt to curb the ever increasing death toll on Irish roads.
