A father assaulted a "good Samaritan" who helped his lost son, who has an intellectual disability, when the pair became separated during a hike.
The man, who The Canberra Times has chosen not to name, was fined $1000 in the ACT Magistrates Court on Wednesday.
He had previously pleaded guilty to assault occasioning actual bodily harm.
Agreed facts state on March 3, 2023, the man was at Mount Ainslie Nature Reserve with his nine-year-old son, who has an intellectual disability and diagnosed Autism.
About 7.45pm two people found the boy crying after he became separated from his father.
The boy told the people his name but was not able to communicate further details.
When they couldn't find the child's parent the strangers took him back to the carpark, and the boy directed them to his father's unlocked vehicle.
The child sat in the car while the two people waited, worried it was getting dark.
About 8pm, the panicked father arrived and was concerned to see his child, crying, with two strangers.
"He thought they might have been kidnapping [his son] or having attempted to harm him," the facts state.
The dad then yelled at the strangers asking them why they took his son and telling them to go away.
One of the people responded that he should be thanking them, rather than yelling at them, and a physical fight started.
The dad punched the other man two or three times to the face, causing an orbital fracture, a swollen eye and a bloody lip.
The father told police he felt his actions at the time were necessary to defend his son and himself.
In an impact statement, read to the court on Wednesday, the victim said he was "constantly afraid" someone would assault him again.
"The bushland area has made me afraid I am going to be hit there," he stated.
"I'm afraid of strangers and everyone is a potential threat.
"It is time that [my attacker] be held accountable for his actions."
Legal Aid lawyer Stephanie Corish acknowledged her client's actions were "beyond reasonable when it comes to self-defence", but said his "stress and heightened emotions at that time were very real".
"[The assault] is a one off, very isolated incident and a total outlier to the good person and good father [my client] is," she told the court.
Magistrate Robert Cook stated the victim was "doing the right thing, a good Samaritan", when the man "makes no attempt to clarify what's going on" and attacked.
The magistrate said this "act of violence" had occurred in the presence of a child.
Mr Cook told the father that while his actions "might be one of impulse and responsiveness", how he responded and "what you did was a complete overreaction".