A motorist who was travelling at 155 km/h in a 100 km/h zone in the Letterkenny area has been tested positive for cocaine and cannabis.
Gardaí from the Letterkenny Roads Policing Unit detected the motorist speeding on Tuesday evening, and subsequently the vehicle was stopped.
The driver was then tested for drugs.
An arrest was made and court proceedings will follow.
Gardaí have repeated their message to motorists to slow down and to never drive while under the influence of alcohol and/or drugs.
A spokesman added: "Always make responsible decisions when it comes to road safety."
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