The cruiser was parked on Highway 403 in Brant County on Thursday afternoon with its emergency lights activated.
Police say a passing vehicle narrowly missed the cruiser and knocked a pylon into it.
The officer stopped the vehicle and the driver was taken to a police station for a blood-alcohol test.
Richard William Doxtator, 34, of Brantford, has been charged with impaired driving and driving with a blood-alcohol level over .08.
He is due in court Nov. 7.
