Niagara police stopped about 650 vehicles during RIDE checks in Port Colborne and Niagara Falls last night.
A total of 20 drivers were asked to provide breath samples and all were in the acceptable range.
Police however did come across a few drivers where an odour of cannabis was present.
Three charges were laid against the drivers for having cannabis readily available to them and a further charge issued to a person under 19 years of age for possessing cannabis.