Failure to conduct a proper criminal investigation found to violate European Convention

The Commissioner of Police v Alio Korau [2015] EWCA Civ 646


The Court of Appeal held that Article 3 of the European Convention of Human Rights (Convention) imposes a positive obligation on police to conduct a proper investigation into credible or arguable allegations of criminal conduct.


The case involved two conjoined appeals concerning the alleged failure of two police forces, the Metropolitan Police Service (MPS) and the Greater Manchester Police, to properly investigate crimes committed against the claimants.

The first claim concerned two women, DSD and NBV, who were the victims of sexual assault by London taxi driver, John Worboys. Between 2002 and 2008 Worboys committed over 105 rapes and sexual assaults against women who were travelling in his taxi late at night. Each case had a similar modus operandi – Worboys administered drugs and alcohol to the women and then sexually assault them whilst they were incapacitated. The women were left confused, disorientated, and could only partially recall their ordeal. 

Both DSD and NBV reported their respective assaults to the MPS. However, when DSD first reported her assault she was mischaracterized as a drunk and drug addict, and was not treated as a victim of crime. Worboys transported DSD to the police station (after being persuaded to take her by a Good Samaritan third party) and was treated as a model citizen. Police did not record Worboys’ personal details or obtain his vehicle registration. Whilst a basic investigation ensued in both cases, each was seriously mishandled.

The second claim was brought by Alio Koraou, who was the victim of an assault by two men in a Manchester pub in 2011. He described the men to police as “white males”, and explained that one of the men had bitten his ear, so that it was partially detached. Although the police commenced an investigation, a number of shortcomings were subsequently exposed including the failure to obtain statements from relevant witnesses (i.e. door staff at the pub), the failure to obtain CCTV footage and the failure to accurately record details of the event.

The DSD/NBV and Koraou claims were brought under sections 7 and 8 of the Human Rights Act 1998. Broadly, those provisions allow a person to bring proceedings against a public authority where that public authority has acted in a way that is incompatible with a Convention right. The relevant Convention right in the present case is Article 3, which states:

“no-one shall be subjected to torture or to inhuman treatment or degrading treatment or punishment”

The primary issue before the Court was therefore whether the alleged failures of the police amounted to a violation of Article 3 of the Convention.


The Court of Appeal held that Article 3 of the Convention imposes a positive obligation to investigate allegations of inhuman or degrading treatment. In doing so, it categorically rejected the MPS’s argument that the negative terminology of Article 3 (i.e. “no-one shall be subjected…”) prevented a finding of a positive duty to investigate. According to Lord Justice Laws, such a construction was “merely to point to the literal meaning of the provision” and was “blind to the jurisprudence on Article 3”.

The Court was also not persuaded by the MPS’s argument that a duty to investigate only arises where the State is complicit in the alleged substantive breach of Article 3 of the Convention. Instead, it noted the long line of Strasbourg and common law authoritywhere the Court repeatedly made it clear that the positive obligation to conduct an official investigation where an individual has claimed that he or she has been seriously ill treated in breach of Article 3 is not limited to cases of ill treatment by State agents.

The Court did however observe that not all minor investigatory failures on the part of the police would necessarily amount to a breach of Article 3 of the Convention. The nature and scope of the investigation required will depend on the factual matrix of each case.

In other words, the investigative duty imposed by Article 3 of the Convention may be applied with various degrees of rigour - there is a sliding scale from systematic torture by State agents (at one end of the scale) to misconduct by private individuals narrowly surmounting the minimum threshold for the engagement of Article 3 (at the other). The Court observed that in circumstances where non-State agents have engaged in serious violent crime, a “proper criminal investigation” by the State is likely to be required.

Applying the principles to the DSD/NBV factual matrix, the Court found that the MPS had failed to conduct a “proper criminal investigation”, referring to the systematic and operational investigative failures (identified at first instance by Green J). The relevant systematic failures included:           

  • the failure to provide proper training to the relevant officers investigating DSD/NBV’s case;
  • the failure to adequately supervise and manage;
  • the failure to maintain confidence with the victims; and
  • the failure to allocate appropriate resources to the case.

The relevant operational failures included:

  • the failure to record relevant facts;
  • the failure to interview key witnesses;
  • the failure to collect relevant evidence (including CCTV footage); and
  • the failure to believe the victims or take their complaints seriously.

In light of the above, the Court found that the MPS had violated Article 3 of the Convention. The Court did not however reach the same conclusion in the case of Koraou. Affirming the trial judge’s decision, the Court accepted that Koraou’s case was “on the margin of what might be properly described as in human or degrading treatment”, and emphasised the “need to avoid an unacceptable burden being imposed on the police”. 

Whilst the Court identified shortcomings in the investigation of Koraou’s assault, it accepted that a number of positive steps were taken by the investigating officers, particularly at the scene. It was also relevant that there was an inconsistency in the evidence provided by the appellant (namely, that a “white” male had bitten his ear) and independent evidence from door staff (namely, that the offender was “black”). In these circumstances, the Court held that a wider margin was to be afforded to the State when determining the means of compliance with the investigatory duty of Article 3 of the Convention. 


The Court of Appeal’s decision in DSD/NBV and Koraou provides important clarity on the nature and extent of the obligation to investigate alleged criminal conduct under Article 3 of the Convention.

The decision reinforces that whilst the State has a positive duty to investigate alleged criminal conduct, it enjoys a margin of discretion as to how it complies with that duty – a margin which widens at the bottom end of the scale (i.e. negligence by non-State agents) and narrows at the top end of the scale (i.e. systematic and deliberate torture by State agents).

The full text of the decision can be found here.

Madeleine McIntosh is a Law Graduate at King & Wood Mallesons