The Metropolitan Police Service (MPS) is not immune to surveillance related controversy. From its role in the phone hacking scandal, to the sexual exploitation of activists by its ‘Special Demonstration Squad’, it may be no exaggeration to say that the force has attracted more criticism for its ill-fated surveillance activities than any other in recent years. Little wonder, then, that its decision to roll out live facial recognition technology (FRT) in public spaces has raised eyebrows. The MPS is introducing FRT in the face of fierce criticism, threatened legal action, and an independent evaluation, which dismantled almost every aspect of the methodology underpinning their ‘trial’ of the technology with forensic precision.
This is certainly a bold move, as FRT is deeply divisive. Is it legal? The MPS have published a ‘Legal Mandate’ for their use of live FRT. It identifies the general powers of a constable at common law to fulfil his basic duties as the legal basis for using the technology, and goes on to identify several statutes, secondary legislation, and internal policy documents that regulate how the MPS will use FRT. Others have considered the extent to which live FRT complies with existing statutory regulations. Here, the focus is on evaluating the common law as an adequate legal basis for using FRT.
To support its Legal Mandate, the MPS relied heavily on a decision of the High Court of Justice in R. (Bridges) v Chief Constable of South Wales Police  EWHC 2341 (Admin) – where a campaigner from Cardiff failed to convince the Court that his human rights had been violated after his face was scanned on two occasions by the South Wales Police. This decision seems to have emboldened the MPS to operationalise FRT, relying solely on the basic common law powers of a constable to protect life, prevent and detect crime, and bring offenders to justice as the legal basis.
There is no question that Bridges supports the MPS’s position. In rejecting Mr Bridges’ contention that there must be some specific statutory basis for the use of live FRT, Haddon-Cave LJ and Swift J relied on the following passage from Rice v Connolly  2 QB 414 at 419:
“[I]t is part of the obligations and duties of a police constable to take all steps which appear to him necessary for keeping the peace, for preventing crime or for protecting property from criminal damage. There is no exhaustive definition of the powers and obligations of the police, but they are at least those, and they would further include the duty to detect crime and to bring an offender to justice.”
Drawing on more recent authorities in R (Wood) v Commissioner of Police of the Metropolis  1 WLR 123 and R (Catt) v Association of Chief Police Officers  AC 1065, the High Court held that this general power of the police covers the use, retention, and disclosure of imagery of individuals for any of the duties articulated in Rice. Haddon-Cave LJ and Swift J observed that, in his leading majority judgment in Catt, Lord Sumption held that there is an important distinction between ‘intrusive’ and ‘non-intrusive’ methods of gathering personal information. Live FRT was the latter and only the former fell outside the common law powers of the police. The High Court ruled that the distinction turned on whether there was a physical intrusion with a person’s rights vis-à-vis his or her home or interference with his or her bodily integrity . It seems that only these forms of ‘physical’ intrusion require a statutory legal basis.
This is a significant finding, as it permits the police to use new overt surveillance technologies like live FRT operationally, without Parliament authorising this use. It puts the police collection and processing of biometric data by FRT in a separate category to other forms of biometric surveillance, such as DNA and fingerprint collection. These tend to require ‘physical intrusion’ and, as such, have a statutory legal basis. The effect of the High Court’s interpretation of these cases is that statutes are only relevant in so far as they place limitations on how live FRT is used by the police. Thus, the police are free to trial and use these new technologies in the absence of the democratic mandate that legislation passed by Parliament provides. If this is the case, there is no need for police live FRT to be approved by our elected representatives, usually following robust debate on the implications this use, and consideration of expert evidence scrutinised by Select Committees. The decision to use live FRT is a matter for police to decide for themselves; their discretion on this matter is fettered only by the limits of their common law powers which, as the Court in Bridges acknowledged, are expressed in ‘very broad terms’ .
It is difficult to fault Haddon-Cave LJ and Swift J’s interpretation of recent authorities in Wood, and Catt. These authorities do suggest that the general common law powers of the police set out in Rice extend to the collection, use, retention and dissemination of facial images. The problem is that, in interpreting the common law powers of the police so broadly, these authorities have sent the law down a wrong path.
Notwithstanding the rulings in Catt and Wood, it is not clear that the passage in Rice was conferring a broad discretion upon the police in this way. In Rice, the appellant successfully argued that the offence of obstruction of justice was not made out in circumstances where he merely refused to provide his name or other assistance to a police constable in the course of his investigation into a series of breaking offences. Lord Parker CJ held that police constables have a duty to take steps which appear necessary to prevent and detect crime. However, as Val Aston notes, this finding was categorical. Lord Parker CJ also held that there are clear limits on this power; one being that citizens are not under a general legal duty to assist the police by providing them with information. This was the unambiguous ratio of Rice.
It is one thing to hold that the common law power to prevent crime and bring offenders to justice is good enough for the police to ask for identifying particulars of a person seen in the vicinity of reported criminality (even though the person may be under no legal obligation to comply with the request). It is quite another for this same power to support the use of myriad biometric and/or algorithmic technologies, which facilitate the use and collection of ever-more sensitive personal information by public authorities. Live FRT enmeshes physical and informational forms of surveillance by collecting information from the physical body of the person and breaking this down into an information structure, which can then be processed. The High Court’s distinction for fleshing out the scope of the common law powers of the police, between physical and informational intrusions, seems unfit for this novel policing landscape. It has allowed the powers of the police enunciated in Rice to be extended too far.
For now, the MPS can rely on broad common law powers to use live FRT, but its decision to do so may prove unwise. Bridges was qualified and is subject to appeal. The Court acknowledged that the legal framework governing live FRT should be strengthened further and, since this judgment, the Information Commissioner has called for the use of FRT to be placed on a statutory footing. In recent years, the European Court of Human Rights has also expressed concern that the common law powers of the police are so broad as to create a risk of ambiguity or extensive interpretation (See S and Marper v United Kingdom  ECHR 1581 at ; Catt v United Kingdom  ECHR 76 at -)
We are at an embryonic stage in our efforts to regulate the police use of algorithms. Given the legal uncertainty, it is curious that the MPS has chosen this moment to begin incorporating FRT into its operational surveillance arsenal. It may soon find itself on the wrong side of the law.