Costello v Chief Constable of Northumbria

The court held that, in exceptional circumstances, a police officer may owe a legal duty of care to a fellow officer to intervene where the officer has assumed or acknowledged a specific responsibility and failure to act exposes the colleague to unnecessary risk of physical injury. The general rule that the police do not owe an enforceable duty in the investigation or suppression of crime remains, but it is not absolute and allows narrow, incremental exceptions where a specific assumed responsibility or positive breach creates foreseeable harm.

The respondent police sergeant (the plaintiff) was attacked by a prisoner while in a cell. A nearby inspector, who accepted he had a duty to assist, did not intervene. At first instance the judge found that the inspector had stood by and did nothing and that his failure caused or materially contributed to the injury. The Chief Constable appealed, arguing that public policy and established authorities preclude imposing such a positive duty on police officers in operational circumstances. The Court of Appeal was asked to decide whether a duty of care in tort could arise between police colleagues in these circumstances and whether the Chief Constable was vicariously liable.

1. Disposition: Appeal dismissed. The Court of Appeal held that on the extraordinary facts found by the trial judge a legal duty of care arose and that the Chief Constable was vicariously liable for Inspector Bell's breach. May L.J. gave the leading judgment; Hirst L.J. and Sir Christopher Slade agreed.
2. Ratio: A close working relationship and an acknowledged or assumed responsibility may give rise to a duty to take reasonable steps to protect a colleague from foreseeable physical harm. The duty is incremental to, and does not abolish, the general policy-based immunity recognised in [1989] 1 AC 53 (Hill).
3. Scope and limits: The Court emphasised that the general principle in Hill — that police do not owe a broad duty to the public in investigation and suppression of crime — remains. Exceptions arise narrowly where the police have assumed responsibility, where there is positive negligent intervention, or where a specific operational duty or standing order is breached (see [1982] 1 WLR 349 (Knightley v. Johns)).
4. Public policy: Public policy considerations may preclude imposition of duties in many operational settings. Those considerations were weighed against countervailing public interest factors, including the expectation that officers will protect colleagues and that some wrongdoing should not be left to internal discipline alone.
5. Practical guidance: Liability may arise where (a) an officer is in close attendance for the specific purpose of providing assistance; (b) the officer acknowledges or assumes the duty; and (c) failure to act exposes the colleague to unnecessary risk which was foreseeable. The present case met these criteria.
6. Order: Appeal dismissed; costs to the respondent; leave to appeal to the House of Lords refused.

• High Court (Queen's Bench Division): Trial before Astill J; judgment for the plaintiff on duty and breach (30 July 1997).
• Court of Appeal (Civil Division): Appeal heard 3 December 1998; appeal dismissed (May L.J., Hirst L.J., Sir Christopher Slade).