A police car patrolling Baulkham Hills at about 12.25pm on Monday was allegedly almost hit by a silver Toyota Camry as it left a driveway.
Police said the officers stopped the driver, a 43-year-old woman, and allege it “quickly became clear” she was drunk.
She returned a breath test over seven times the legal limit – .371, according to an image police posted on Facebook.
A blood alcohol level of 0.3 or more is likely to render a person unconscious.
The woman was arrested and taken to Castle Hill Police Station, where breath analysis returned a reading of 0.269g of alchol per 210 litres of breath.
The woman’s licence was suspended and she was charged with high range drink driving.
Police also confiscated her car keys and reported the incident to Family and Community Services.
The woman will face court on the drink driving charge in October.