During an interview on Good Morning America, Witherspoon repeatedly apologised for her behaviour during the 19 April traffic stop.
A police report states that Witherspoon asked a Georgia state trooper, "Do you know my name?" and added, "You're about to find out who I am."
In Thursday's interview, the Oscar-winning actress said she has "no idea what I was saying that night."
She said she had "one too many" glasses of wine, and panicked after she and her husband were pulled over.
Witherspoon faces a 22 May court hearing.
Her husband, Hollywood agent Jim Toth, was charged with drunken driving and is due in court 23 May.