A father had his aggravated assault conviction overturned in court this week after a judge said his decision to smack his child was 'not unreasonable'.

In March 2014, the father - an Air Force pilot - is said to have smacked his son, 12, three times on the thigh telling him: 'if you're going to act like a four-year-old, I'll treat you like a four-year-old.'

On Monday Justice David Peek quashed the conviction telling the South Australian Supreme Court disciplining one's child does not 'transform' them into a criminal, The Advertiser reported.

A father who smacked his child had his assault conviction overturned in the Adelaide Supreme Court (pictured) on Monday

In handing down his judgement Justice Peek said there was some redness but no bruising left by the smacks, and said there was no issue with the discipline.

'It is very important that parental conduct which is not considered unreasonable in the Australian community should not be stigmatised as criminal offending in a criminal court,' he said.

The judge also described the pilot, 43, as being 'of excellent character and work ethic' and a 'good, loving father'.

'The pilot gave evidence that he tried to instil self-discipline in his son and values similar to those of the Air Force including respect, dignity and integrity,' Justice Peek told the court.

The father, a 43-year-old Air Force pilot, is said to have slapped his child three times on the leg for misbehaving

The 43-year-old had taken other steps to attempt to disciple his child who was behaving 'indignantly' such as putting him in 'time-out' before the smacking incident.

The pilot's former wife, with whom he shares custody of the 12-year-old boy with, is said to have reported the incident to police.

However Justice Peek ordered the conviction be overturned and the charge dismissed, as the potential consequences of a conviction for the pilot were unreasonable.

Psychologist Dr Michael Carr-Gregg (left) and Terri Kelleher from the Australian Family Association have weighed in on the debate

Experts have since weighed in to the debate, with Terri Kelleher, spokeswoman for the Australian Family Association, saying the landmark decision was a win for parents.

'We all have to learn boundaries, and it's better we learn them as early as possible in life from the parents who love us and want to provide a future for us,' she said.

Meantime psychologist Dr Michael Carr-Gregg said while he also agreed with the ruling, parents should use other non-violent discipline techniques calling smacking a 'very, very, dumb thing to do'.