Niagara Regional Police suspended one driver's licence as part of RIDE Checks in Welland and Thorold.
Officers set up the checkpoints on Friday, stopping approximately 600 vehicles and asking 21 drivers fro breath samples.
The one driver who registered in the alert range has had their licence suspended for three days.
Another driver was charged with operating a vehicle with a suspended licence and 11 other tickets were handed out for various traffic related offences.