His co-offender, and girlfriend, was fined and placed on a good behaviour order for her part in the road rage incident in November last year.

Daniel Forsyth, 29, and Samantha Carpenter, 23, were both sentenced in the ACT Magistrates Court on Monday.

The court heard the offenders had returned from the south coast – where they had scattered Carpenter's father's ashes – when the victim cut them off by pulling into their lane without checking his blind spots.

Forsyth was forced to swerve to avoid a collision. Enraged, they sped up, abused the two victims, and then forced them from the road.

Carpenter jumped out of her car and hit the driver's windscreen before opening the door and punching him in the shoulder.

The driver apologised repeatedly, but Forsyth punched him in the right-eye and kicked him.

Forsyth then produced a sheathed knife and said words to the effect of: "This is not your country you bloody Indian, go back to your country and do it there."

The driver and passenger both got out of the car, and Forsyth kicked the passenger. Carpenter grabbed and scratched the driver and accused him of nearly killing her family.

The victim continued to apologise, and the offenders drove away. But they returned to threaten the driver after seeing him on his phone.

At a hearing last month, Chief Magistrate Lorraine Walker found Forsyth guilty of unlicensed driving, menacing driving, assault occasioning actual bodily harm, common assault, and possessing an offensive weapon with intent.

Carpenter was found guilty on two counts of common assault.

Ms Walker dismissed as implausible Forsyth's claim that the knife had actually been his mobile phone in a leather case.

During sentence submissions, prosecutor Richard Cawte said the offenders' reaction had been "disproportionate and manifestly excessive".

Mr Cawte said the offenders had shown no remorse, no victim empathy, and no insight into their crimes.

Forsyth's lawyer, Andrew Fraser, said his client had been distressed to be labelled racist.

Mr Fraser argued Forsyth suffered from mental health issues that would be exacerbated if he were jailed.

Carpenter's defence lawyer, Mary-Anne Ellis, said the offender had been emotional with the scattering her father's ashes just before the incident.

Ms Ellis said her client could not remember physically touching the victim.

Ms Walker sentenced Forsyth to 10 months' jail, to be served in full-time custody for three months, with the remaining seven months suspended upon entering an 18-month good behaviour order.

He was also fined $500.

A tearful Carpenter was ordered to pay a $500 fine and sign a one-year good behaviour order.

Forsyth continued to protest his innocence as he was taken to jail by guards.