Susan Walsh/AP Photo

The drugged-driving case against Kerry Kennedy will move forward, a judge ruled today, despite a request by her lawyers to have it dismissed.

Kennedy, a daughter of Robert F. Kennedy and the ex-wife of New York Gov. Andrew Cuomo, was arrested in July 2012 after state police said she swerved her Lexus into a tractor-trailer on a New York highway and was found slumped over the wheel of her car.

She was charged with driving impaired. Not long after the accident, she told reporters that she only remembered getting on the highway.

"Then I have no memory until I was stopped at a traffic light and a police officer was at my car door," she said previously. "I want to apologize to the driver of the truck who I apparently hit and to all those I endangered."

Kennedy, 54, has pleaded not guilty to driving under the influence of drugs. She told police that she may have taken Ambien that morning after mistaking it for her thyroid medication.

RELATED: Kerry Kennedy crash raises questions about Ambien use.

Ambien is an FDA-approved sleep medication. When taken during the day, however, the little pill can cause slurred speech, blurred cognition and erratic behavior, experts said.

"Ambien makes us go into this amnesiac state," said Dr. Shelby Harris, director of the behavioral sleep medicine program at Montefiore Medical Center in New York who has not treated Kennedy. "Basically your brain is shut off but your body is moving."

Toxicology reports in July showed 14 nanograms of zolpidem per milliliter of Kennedy's blood, according to the Associated Press. Zolpidem is Ambien's generic cousin. Her blood and urine samples were negative for alcohol or other drugs.

Kennedy waived her right today to attend jury selection because she would be out of the country, continuing her father's efforts to fight child labor and end child slavery.

She told the judge today that she would be back for the start of the trial, which is slated to begin in February.

ABC News' Susan Donaldson James and Alyssa Newcomb contributed to this story.