Lisa McCormack (22) was jailed for two years and four months when she appeared in the Dunedin District Court yesterday after admitting the April 25 attack, which took place at traffic lights in South Dunedin.
The 74-year-old driver pulled up to the intersection of King Edward St and Hillside Rd with his 80-year-old sister, a nun, in the passenger seat.
McCormack had been taking LSD with friends and had what she described as a panic attack when her friends left her.
Believing her heart was going to stop and that she needed to get to hospital, the defendant dashed through traffic and pulled open the driver's door.
"Get out of the car. Give me the car," McCormack screamed.
She continued to yell her demands as she repeatedly punched the man in the head.
McCormack then crawled over the driver.
"Squashing" the seated nun, she kicked at the driver while flailing her arms.
"The level of violence you meted out when you got yourself in that car was staggering, using one of the occupants as a lever to force the driver out," Judge Michael Crosbie said.
"This episode was simply awful - elderly people out, minding their own business."
Despite being peppered with numerous blows, the driver managed to get out of the vehicle before pulling McCormack out by the ankles.
Members of the public restrained her on the footpath while the victim locked his car.
But it was not over.
McCormack ran into the road and again tried to access the vehicle where the man once again repelled her.
He suffered cuts and bruises, while his sister sustained a cracked rib.
The defendant wrote a letter to the victims, the court heard, saying she was deeply sorry.
Had it been her own grandparents put through such an ordeal, she would have been heartbroken, she said.
The judge said a prison term might not have been the outcome but for McCormack's history of similar violence.
In her letter, the defendant - who had a chaotic lifestyle along with a history of "unsafe relationships" and substance abuse - said the case was the wake-up call she needed.
However, she admitted the prospect of raising her baby in prison was "devastating".
McCormack was convicted of injuring with intent to injure and injuring with reckless disregard.
Counsel Brendan Stephenson said his client planned to make the most of her time behind bars and take any rehabilitative opportunities.
