The “Black Cab Rapist” – Court of Appeal rules on Article 3 investigative duty

6 July 2015 by

Metropolitan Police

Commissioner of the Police for the Metropolis v DSD and NBV and Alio Koraou v Chief Constable of Manchester [2015] EWCA Civ 646 – read judgment

The Court of Appeal has ruled that the police have a positive duty under Article 3 ECHR to conduct investigations into alleged ill-treatment by private individuals. There is a sliding scale from deliberate torture by State officials to the consequences of negligence by non-State agents. The margin of appreciation enjoyed by the State in terms of complying with the Article 3 procedural duty widens at the bottom of the scale but narrows at the top.


This was an appeal brought by the Metropolitan Police Service (MPS) against the decision of Green J in the High Court that the police force were in breach of the prohibition on inhuman or degrading treatment or punishment under Article 3 ECHR. A summary of the judgment at first instance can be found here.

The claimants were two women, DSD and NBV, who had been victims of rape and sexual assault committed by John Worboys, the “black cab rapist”. Administering sedative drugs and alcohol to his passengers, Worboys was the perpetrator of more than 105 assaults on women between 2002 and 2008.

In a conjoined appeal, the claimant Alio Koraou appealed a finding against him by HHJ Platts. He had been subject to an assault in a bar and part of his ear had been bitten off.

Both of these claims alleged that the failures of which the police were accused constituted violations of a duty to investigate said to be inherent in the right guaranteed by Article 3.


The Court of Appeal rejected submissions made on behalf of the MPS that a positive duty to investigate was not part of domestic law. It held that allegations of ill-treatment of the gravity stipulated by Article 3 gave rise to a duty under that Article to conduct an official investigation. Moreover, this obligation was not limited solely to cases of ill-treatment by State agents, but could arise where crimes were committed by private actors.

The reach and nature of the investigative duty

The Court emphasised that an appreciation of the reach and nature of the investigative duty under Article 3 demanded a broader consideration of the aims of this part of the ECHR. It was important to keep in mind the Article’s overall purpose.

The idea at the core of the Article is that of safeguarding or protection in all the myriad situations where individuals may be exposed to ill-treatment of the gravity which the Article contemplates” [para. 44].

Reference was made to a sliding scale: from deliberate torture by State officials to the consequences of negligence by non-State agents. The energy required of the State to combat or redress these ills is “no doubt variable, but the same protective principle is always at the root of it” [para. 45].

Further, the margin of appreciation enjoyed by the State as to the means of compliance with Article 3 widens at the bottom of the scale but narrows at the top. At the lower end of the scale where injury happens through the negligence of non-State agents, the State’s provision of a judicial system of civil remedies will often suffice. Serious violent crime by non-State agents is of a different order, lying higher up the scale. Such cases, which included those of  the respondent women, generally require a proper criminal investigation by the State.

Were the MPS in breach of their duty?

The Court went on to consider whether the judge had placed the cases in front of him too high on the sliding scale in terms of the degree of rigour required of the police investigation. A contrast between the ECHR and common law negligence was in this regard crucial. Whereas the purpose of English private law is compensation for loss, the strategic aim of the ECHR is to secure minimum standards of human rights protection. This distinction marks important differences in practice.

The contrast between damages as of right and compensation at the court’s discretion is one. But another, in my judgment, goes to the standard applicable to the ascertainment of breach of the Article 3 investigative duty, as compared with what might constitute breach of a common law duty of care. Because the focus of the human rights claim is not on loss to the individual, but on the maintenance of a proper standard of protection, the court is in principle concerned with the State’s overall approach to the relevant ECHR obligation” [para. 67].

The enquiry into compliance with the Article 3 duty is first and foremost concerned, not with the effect on the claimant, but with the overall nature of the investigative steps to be taken by the State” [para. 68].

Drawing on the account of Green J, the Court noted the judge’s findings that there were systematic and operational failures in the cases of both claimants. Applying the above legal principles to the facts, the Court held it to be “inescapable” that Green J was right to find a violation of Article 3.


In the second of the conjoined appeals, the Court affirmed the approach of HHJ Platts: a finding that there were clear failings in the police investigation would not lead in every case to liability under Article 3.

It had been noted by the judge that this was not the most serious of cases and that the allegations made by the Claimant were of questionable reliability. In his judgment it was not, therefore, a case where it would have been reasonable to require that the investigation left no stone unturned. Account had to be taken of the fact that police resources were limited. Further, this was not a case where the police did nothing.

The Court concluded that HHJ Platts had weighed the proved deficiencies of the investigation, its difficulties as he found them to be, and the gravity of the case. His decision to dismiss the claim could not sensibly be faulted.

Hannah Lynes

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