Neil Payne took the law into his own hands and stormed after the motorist and broke his cheekbone and smashed up his car.
Yesterday, Perth Sheriff Court was told Payne had formed a hatred of drunken driving after a friend was knocked down and killed by a drink driver.
The court heard that the 24-year-old gardener and tree surgeon had never been in any trouble before.
Payne, of Dunning, admitted attacking the man - who cannot be named - by punching him on the head to his injury in the Perthshire village on 11 August this year.
He also admitted vandalising the man's car by kicking it and causing more than £300 damage to the tail-lights and fittings.
Fiscal depute Stuart Richardson said: "The accused was in a licensed premises and so was the complainer, who is 68.
"The complainer had been drinking but decided he would drive home.
"Mr Payne was aware of this and left to make his way to the complainer's home address.
"He found him there and started going on about drink driving and unfortunately things went far too far and punched him on the head, causing an injury consistent with a broken cheekbone."
Payne was fined £500 and ordered to pay £300 compensation for the damage to the car.