(Adds comments from prosecution witnesses)
By Victoria Cavaliere
WHITE PLAINS, N.Y. Feb 24 (Reuters) - A Kennedy family member's groggy behavior after her 2012 arrest for side-swiping a tractor trailer in New York was not the result of a criminal act but of mistakenly taking a sleeping pill instead of thyroid medication, her lawyers argued at her trial Monday.
Kerry Kennedy, 54, daughter of assassinated Senator Robert F. Kennedy and the ex-wife of New York Governor Andrew Cuomo, has pleaded not guilty to a charge of driving while impaired.
"This case is about a mistake, plain and simple," defense attorney Gerald Lefcourt said in his opening statement in Westchester County Court in White Plains, about 35 miles (56 km) north of New York City.
Lefcourt said it was a medication mix-up that led to Kennedy's arrest for erratically driving her silver Lexus on Interstate 684 near North Castle in Westchester County the morning of July 13, 2012.
Kennedy, who wore a gray dress and jacket and black-rimmed glasses in court, is expected to take the stand later in her trial, due to run about a week.
Her mother, Ethel Kennedy, widow of Senator Kennedy, was also in the courtroom as Lefcourt described Kennedy as a devout Roman Catholic and a devoted humanitarian and mother who would never willfully drive while impaired.
"If she would have realized her mistake and known she was not in the right condition to drive her car that day, she would never have continued on the road," he told the jury.
Kennedy, who is also the niece of assassinated President John F. Kennedy, "is not seeking any advantage here because of her famous family," Lefcourt said. "On the other hand, she should not be punished because of it."
SERVING TIME UNLIKELY
A jury trial is unusual for a relatively minor unclassified misdemeanor. If convicted, Kennedy could face up to a year in prison, but with no prior criminal record, it is unlikely she would serve any time behind bars, court officials said.
A toxicology report after Kennedy's arrest showed she had the drug zolpidem, which is sold under the brand name Ambien, in her system. The drug is a slow-acting medication to induce sleep and overcome insomnia.
Prosecutors said Kennedy continued to drive her car after realizing she was impaired, endangering herself and other drivers, before running off the road and passing out behind the wheel.
Witnesses testified on Monday that they saw her Lexus traveling at high speed, tailgating and veering into other lanes.
Henry Myers, who saw Kennedy collide with the tractor trailer and then called 911, said her "car took off pretty quick. She got into the middle lane and was swerving into the other lanes."
Nobody was injured during the accident.
"It was an ominous and regrettable day for this defendant Kerry Kennedy," said Assistant District Attorney Stefanie DeNise during opening statements. "Still she continued to operate her car in an unsafe manner."
Kennedy drove about 5 miles (8 km) while swerving into other lanes of traffic, the grassy median and eventually a tractor trailer, prosecutors told the jury.
The prosecution also called three law enforcement officers to the witness stand, including William McClure, a North Castle police officer.
McClure said when he approached Kennedy's car, he saw "the front passenger tire almost completely shredded. There was black marks, and damage to the back passenger side of the car."
He testified that Kennedy appeared disoriented, her speech very slow and deliberate. She was dressed in gym clothes and at first told officers she was headed to New York City before telling them about 20 minutes later she was headed to a nearby gym, McClure said.
"For a while we had her sit in the back of her SUV so she wouldn't fall," he said. (Editing by Barbara Goldberg, Grant McCool and Mohammad Zargham)