A US woman arrested after speeding through a stop sign asked police to let her off because she is "a clean, thoroughbred white girl", officers say.

The arresting officer, who is white, detailed in his official report how Lauren Cutshaw, 32, appealed to him for special treatment based on her race.

When asked why, Ms Cutshaw replied: "You're a cop; you should know what that means," the report states.

She was arrested on Saturday night and also charged with drug possession.

Ms Cutshaw was pulled over after she drove through a stop sign at 60mph (96km/h) in Bluffton, South Carolina.

As officers began investigating, she argued that she should not be arrested.

Ms Cutshaw told officers she had perfect grades her whole life, was a cheerleader and sorority girl, had graduated from a "high accredited university" and that her partner was a police officer, according to a law enforcement report viewed by local news site The Island Packet.

The officer's report stated: "Making statements such as these as a means to justify not being arrested are unusual in my experience as a law enforcement officer and I believe further demonstrate the suspect's level of intoxication."

When she was pulled over, Ms Cutshaw's blood alcohol level registered at 0.18% - the legal limit is 0.08% - and she failed sobriety tests.

Her eyes were bloodshot and glassy and she was slurring her words, police say.

She reportedly told officers she only drank two glasses of wine at an upmarket restaurant, saying: "I mean, I was celebrating my birthday."

Police also found marijuana and related paraphernalia in her car. According to the report, Ms Cutshaw said she "may have" smoked earlier that evening.

She was charged at the Beaufort County Detention Center with drink-driving, speeding and marijuana possession.