Dont forget why she was there in the first place. Sleeping off a night on the lash in her car, and failing to give a breath test. As far as I'm aware being drunk in a car, and in possession of the keys accounts to being drunk and in charge of the vehicle, asleep or not.
No evidence she was drunk, or even was asked to provide a breath test.
The only claim of this came from the officer who assaulted her. Is it unreasonable to presume he came up with this story to cover himself after realising the trouble he could have gotten himself into?