DUI: Rand Paul's eldest son William Paul, 22, was cited for a DUI on Sunday in Lexington, Kentucky but not arrested . A son of Republican presidential candidate Rand Paul was pulled over on suspicion of driving under the influence on Sunday. However William Hilton Paul, 22, was not arrested. Paul was driving a 2006 Honda Ridgeline at 11.24am when he crashed into the back of an unoccupied parked car, in Lexington, Kentucky, according to police. Some people nearby heard the crash and alerted authorities. Witnesses said Paul was 'revving his engine' while sitting alone in the truck, reported Kentucky.com. Lexington Police spokeswoman Sherelle Roberts said Paul was treated at the University of Kentucky hospital for minor injuries to his face. Paul failed a field sobriety test, reported Lex18.com. He refused blood and breathalyzer tests at the hospital. Although the 22-year-old had 'bloodshot, watery eyes' and was behaving in a 'belligerent' way according to the report, he was not arrested. Roberts said that is standard protocol for a case in which a DUI suspect is hospitalized. The 22-year-old student is scheduled to be arraigned in Fayette District Court on May 12. Paul,  a senior at the University of Kentucky majoring in communications, has two previous alcohol-related run-ins with the law. In October 2013, Paul was cited for possession of alcohol by a minor by the Kentucky Department of Alcoholic Beverage Control while drinking at a racetrack. In January 2013, Paul was charged with assaulting a female flight attendant, underage consumption, disorderly conduct, and being intoxicated and disruptive when his flight arrived at the airport. Those charges were dropped after Paul completed alcohol education classes and community service. On Sunday,  a police officer cited Paul for operating a motor vehicle under the influence of alcohol and failure of a nonowner/operator to maintain insurance. Paul was alone at the time of the crash. A campaign spokesman said Senator Rand Paul does not comment on any private matters with regards to his family. Rand Paul, pictured on Saturday, a Republican 2016 presidential contender, refused to comment after his son  crashed into a parked car on Sunday in Lexington, Kentucky while under the influence of alcohol .
William Paul was 'revving his engine' while sitting alone in the truck Sunday when passersby alerted authorities in Lexington, Kentucky . Paul failed field sobriety tests before being taken to a hospital for facial injuries - authorities say suspects in that situation are not arrested . Paul had two previous alcohol-related run-ins with the law before turning 21 in 2013 . The 22-year-old is a senior studying communications at the University of Kentucky .