Mercer was driving north in Great King St when she strayed from her lane and slammed into the back of a parked car.
The speed was such that it caused damage to four cars; her car mounted the footpath and hit a road sign before coming to a stop.
When police arrived, Mercer refused to undergo a breath test, then declined to leave her vehicle.
After receiving a warning, the defendant was dragged out of her car and pepper-sprayed.
Yet her resistance continued.
While officers tried to restrain her, she kicked one in the head and bit a second on the hand.
The constable was left with teeth marks but it did not pierce the skin, the court heard.
An evidential test eventually gave a breath-alcohol reading of 553mcg — more than twice the legal limit.
Mercer said she was sorry for her actions but claimed she could not remember much of the incident.
Judge Dominic Flatley acknowledged the defendant's troubled childhood, which was characterised by deprivation and trauma.
Her resulting mental health issues, the court heard, had led to her living a "chaotic lifestyle" where her attendance at therapy and use of prescribed medication was sporadic.
Despite a limited criminal history, Mercer was considered a high risk of reoffending.
"You very clearly need intensive therapeutic rehabilitation that's closely monitored, to ensure change in you and your behaviour," said Judge Flatley.
Mercer was also banned from driving for nine months and ordered to pay $4465 reparation.
