New York State Police arrested her after she allegedly hit a tractor-trailer with her car in Westchester County and left the scene of the collision. She was found nearby with a flat tire, the New York Daily News said.
USA Today said she was cited for driving while ability impaired, but police did not indicate what drugs they suspect she may have taken.
Her spokesman insisted no drugs or alcohol were found in her system at the time of the incident.
"Kerry Kennedy voluntarily took Breathalyzer, blood and urine tests -- all of which showed no drugs or alcohol whatsoever in her system. The charges were filed before the test results were available," publicist Ken Sunshine said in a statement.
Kennedy is due in court Tuesday to answer the charge.