In 2005, the US Supreme Court ruled that police have no Constitutional duty to protect us. The facts of the case involved, “the failure of the police to respond to a woman's pleas for help after her estranged husband violated a protective order by kidnapping their three young daughters, whom he eventually killed.”
This ruling by the highest court was in accord with several previous decisions by lower Federal courts and State courts. The established precedent is, in essence, “Law enforcement agencies and personnel have no duty to protect individuals from the criminal acts of others; instead their duty is to preserve the peace and arrest law breakers for the protection of the general public.”
That quote comes from Lynch v. N.C. Dept. of Justice (1989). Perhaps the most notable case was Warren v. DC (1981). In Warren, three women who had been robbed, raped and held captive for 14 hours while police bungled the victims’ calls to 911, sued the police for negligence. The court ruled, “a government and its agencies are under no general duty to provide public services, such as police protection, to any particular individual citizen,” and absolved police of any liability.