In Chief Constable of The Hertfordshire Police (Original Appellant and Cross-Respondent) V Van Colle , the House of Lords has denied (3 to 2) that there is a civil legal right against the police for failing to take action to prevent criminal violence to the Plaintiff.
The leading case is Osman v United Kingdom (1998) 29 EHRR 245.
In that case the Plaintiff/Complainant was the widow of Ali Osman, and the mother of Ahmet Osman. Mr. Ali Osman was shot dead and Ahmet was wounded by Ahmet’s former teacher. The event was preceded by a history of deviant behaviour by the teacher towards Ahmet which was investigated by Ahmet’s head teacher and reported to the police. The ineffective police response was to “lay an information of careless driving” against the teacher.
In Chief Constable of The Hertfordshire Police (Original Appellant and Cross-Respondent) V Van Colle  there were two instances; in the first (Van Colle) case, Giles van Colle was threatened by and ultimately murdered by a man named Brougham. In the second case Stephen Smith was threatened by his former partner who subsequently attacked him with a claw hammer, seriously injuring him. The threats in both cases had been reported to the police who did nothing effective.
(Strangely, such failures may be common).
The quality of Lord Bingham’s minority judgment is a predictor that the issue will return and be reversed in the future.
He quotes Lord Keith in Hill v Chief Constable of West Yorkshire  AC 53 as saying;
There is no question that a police officer, like anyone else, may be liable in tort to a person who is injured as a direct result of his acts or omissions. So he may be liable in damages for assault, unlawful arrest, wrongful imprisonment and malicious prosecution, and also for negligence. Instances where liability for negligence has been established are Knightley v Johns  1 WLR 349 and Rigby v Chief Constable of Northamptonshire  1 WLR 1242. Further, a police officer may be guilty of a criminal offence if he wilfully fails to perform a duty which he is bound to perform by common law or by statute: see Reg v Dytham  QB 722, where a constable was convicted of wilful neglect of duty because, being present at the scene of a violent assault resulting in the death of the victim, he had taken no steps to intervene.”
He went on to say:
Considerable argument was devoted to exploration of the relationship between rights arising under the Convention (in particular, the article 2 right relied on in Van Colle) and rights and duties arising at common law. Should these two regimes remain entirely separate, or should the common law be developed to absorb Convention rights? I do not think that there is a simple, universally applicable answer. It seems to me clear, on the one hand, that the existence of a Convention right cannot call for instant manufacture of a corresponding common law right where none exists: see Wainwright v Home Office  UKHL 53,  2 AC 406.”
If, as other cases suggest, it is necessary for responsibility to be assumed for a duty of care to arise, then in my opinion the police assumed responsibility by visiting Mr Smith, initiating what was regarded by them as an investigation, assuring him that the investigation was progressing well and inviting him to call 999 if he was concerned for his safety. Public policy points strongly towards imposition of a duty of care: Mr Smith approached a professional force having a special skill in the assessment of criminal risk and the investigation of crime, a professional force whose main public function is to maintain the Queen’s peace, prevent crime and apprehend criminals. He was entitled to look to the police for protection and they, in my opinion, owed him a duty to take reasonable steps to assess the threat to him and, if appropriate, take reasonable steps to prevent it.”
What of a police force which pursues other agendas (“political”) rather than the enforcement of the law? In other words, where they are not so much negligent as complicit?