The police summary said Conn started screaming at the driver, went up to the side of the car and punched him in the face before throwing another punch at him.
As the man drove away Conn's partner kicked his car.
In the Nelson District Court today, Judge Jo Rielly was relaying the facts to Conn - a young woman in her 20s, including that at the time of the assault she was pregnant and had with her a young child.
"Even if there was a close call between you, your child and this man, lashing out in the way you did was entirely unacceptable."
Judge Rielly said the assault had had a significant impact on the man, who was a mature person who now felt unsafe.
"It's simply not acceptable to mete out violence to members of the public.
"It's not only him but his wife who is now fearful of going out alone, because she is fearful of running into you and your (now) ex-partner."
Judge Rielly explained the older couple were now too afraid to drive into a street they normally used out of concern they might see Conn, who at that point spoke up from the dock and said she felt the same now, going out alone now without a partner.
She said if they were now too afraid to drive down her street, they didn't have to.
"If they don't want to come into my street there are plenty of other places to go," Conn said.
Judge Rielly said it simply showed her lack of insight and remorse before sentencing her to nine months' supervision, with a special condition she attends an assessment for help with anger management.
She also ordered Conn, who appeared close to tears, to pay $200 emotional harm reparation.
