Both arrests were made on the motorway over the weekend.
Two motorists have been arrested by Gardaí in Laois for driving under the influence.
The first was an unaccompanied learner driver, who was stopped on the M7 after an alert signaled expired tax and NCT.
Officers said there was a strong smell of cannabis from the vehicle, and the driver failed the roadside drug test.
Gardaí say a blood sample was taken and a prosecution will follow.
Another motorist was arrested on the M8 in Laois, after they were found drunk driving and travelling at 163 km/h.
Gardaí say court proceedings have commenced in relation to that arrest.
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