The man, a doorman from Dundee, allegedly hit his six-year-old son when the boy repeatedly walked off the pavement into the road. A passer-by spotted the man smacking the boy and contacted the police, who charged him with assault.
The case follows the conviction for assault last week of a primary teacher from North Lanarkshire who smacked his eight-year-old daughter. The 48- year-old man was said to have pulled down the girl's pants and smacked her several times on the bottom in a dentist's waiting-room when she refused to have a tooth extracted on Christmas Eve.
The conviction has led to calls for the law on smacking to be clarified.
Moves towards outlawing smacking have been under consideration since a judgment last September by the European Court of Human Rights. In that case, the UK government was ordered to pay pounds 30,000 damages and compensation to a child who was caned by his stepfather at the age of nine. Last week a Department of Health spokesman promised a consultation paper in the summer on "how the law can be strengthened, better to protect children" in the light of the European court's ruling.
The Dundee case occurred on 13 February. According to the father, he had been talking to a friend outside his friend's house when the six-year- old stepped off the pavement into the road several times.
The father, who cannot be named to protect his son's identity, admits that he smacked his child, but denies that the action constitutes assault.
He said: "My son gets a smack if he's playing with something he shouldn't be or if he's messing about on the roads. A smack is better than being hit with car.
"I gave him a passing clout on the backside. I didn't expose his bottom. He didn't cry. He laughs it off half the time."
The man, who is the child's primary carer, said that he had looked after him alone for five and a half years, but that single fathers were often put under the spotlight.
"It's a total farce," he said. "It's out of order. If you can't smack a child, how are you going to stop them doing something?
"It's ridiculous that fathers can't smack their children or it's seen as abuse. I don't believe in that. They deserve a smack of reasonable strength."
The assault charge was laid after police officers visited the family home to investigate the case, said the father. He said police accused him of causing a bruise on the boy's back, but he insisted the injury occurred on another occasion when the boy fell out of a van in which he was playing.
The charge has been passed to the Procurator Fiscal, but so far no further action has been taken.