Taken away: Police took the woman away from her home. Picture: The West Australian

A mother of three is "mortified" after being charged with common assault for allegedly slapping her four-year-old son twice in the face when he had a tantrum at the shops.

The 34-year-old's husband said yesterday that he believed police had overreacted by charging his wife and instead should have let her off with a warning after checking the children were not abused.

The man, who did not want to be named, said he and his wife had not yet decided whether to fight the charge when she faced court but she was mortified by the police intervention.

She allegedly smacked their son when he misbehaved while she was shopping with him, his twin sister and their six-year-old son last month.

"The six-year-old has encouraged the four-year-old to pinch an apple off a shelf, have a bite and put it back - and he has," the man said.

He said his wife paid for the apple and, as punishment, refused to give it to either of the boys but gave it to their daughter.

That had sent the four-year-old boy into a meltdown, who had a tantrum in front of shoppers.

"She has given him a slap on the face," the husband said. "She knows it's not right but it's a spur of the moment thing."

The man said his wife was accused of slapping their son twice but he had tried to dodge the first smack. The man said his wife would not have hit their son hard because she was riddled with arthritis. Police were called and stopped the 34-year-old as she drove out of the carpark.

One officer checked whether the children were injured, while his colleague warned the woman she could expect a visit from police or the Department for Child Protection and Family Support.

The father said that despite his wife's remorse, police arrived at their home the same day and took her away in a paddy wagon.

The man said that his wife was at first pleased that police had intervened because it meant they checked all allegations of bad parenting. But he said the aftermath had caused more damage to their family than the alleged smack.

"In the days afterwards, we didn't feel they were our kids," he said. "We felt like we were babysitting them and couldn't shout at or discipline them. The damage that caused to our family over such a small incident."

The man said they had no previous interaction with child services and DCP had not yet contacted them.