Paris Hilton's younger brother Conrad has been sued for allegedly causing a head-on collision while driving under the influence.

Kathy Auld filed papers against the 22-year-old over the crash which happened on 19 May (16), claiming she spotted Conrad driving erratically in his Range Rover, which was registered to his father Rick Hilton's real estate firm.

In the documents obtained by TMZ.com, Auld alleges Conrad accelerated his car, clipped another vehicle and eventually slammed straight on to her car.

She also claims in the lawsuit that she spotted Conrad looking dazed with both his hands off the wheel moments before the accident. In addition, Auld says witnesses saw the troubled socialite also throw a bong, a device generally used for smoking cannabis or tobacco, out his window, and alleges Conrad was also covered in his own vomit when he exited his SUV.

Auld notes Conrad was prohibited from driving at the time, due to a court-ordered drug treatment program he underwent last year (15).

To make matters worse, the incident happened one day after Conrad struck a plea deal for another car crash in 2014. In that case, he was charged with recklessly evading an officer of the California Highway Patrol on a highway in Palm Springs.

The lawsuit comes just weeks after the hotel heir was released from prison after serving time for a parole violation.