So, I have a question for anybody who knows the law *paging Mr. Reactionary*: If this woman had had the same rap sheet, but was a citizen, would the cops have arrested her if she had a warrant out for her arrest, but was making a call on a domestic abuse claim? If so, the law is kind of messed up regardless of how immigration plays into it.
If she had a warrant out for her arrest, likely. They would have processed her complaint, the warrant would have come up, and there you go. There's very little in the way of immunity for past crimes except for select cases, like bringing in an overdose victim to the hospital.