[BenLurkin]

IIRC California law precludes a person from suing the police for not enforcing the law.

But that’s not quite the same as suing a city for violating the law.

[Alberta's Child]

Even if California law permitted her family to sue the city government, there's a big legal hurdle they'd face.

It's called the principle of "mitigation of damages." Under this common-law principle, the plaintiffs in a case could have any damages diminished or eliminated if it can be demonstrated that the person in question (the victim, in this case) knew the risks involved in the incident and had an opportunity to mitigate or eliminate them, but chose not to.

In other words, the city's strongest defense in this case would be: "It is commonly known that we have been a 'sanctuary city' for years. If this was a problem for the victim, she should have lived somewhere else."

[Gaffer]

There is a Supreme Court case ruling that says the police are not obligated to protect you. They are only there to enforce the law. If they caught the guy, then they “enforced” it in their eyes.