Live facial recognition – five things you need to know

1. What Live facial recognition (LFR) is

LFR is a real-time deployment comparing a live camera feed (or multiple feeds) of faces against a predetermined watchlist to locate people of interest such as missing people or those with outstanding warrants. LFR was first used by policing in England and Wales at the 2017 UEFA Champions League final in Cardiff when Real Madrid played Juventus.

2. How LFR is used

LFR is used to reassure the public, identify people suspected of criminal activity or those who have outstanding warrants. It is also used to protect the most vulnerable in our communities. It can be used to locate missing persons or those suffering with difficulties that may mean they need to be located urgently to help them. 

LFR is often used at large events or in busy areas, typically using mobile LFR vans. The vans have clear signs on the outside and there is also signage in the area to tell people it is being operated. There are also operational staff on the ground to monitor alerts and speak to the public if they have questions about the technology.  

3. How LFR works

Each face that is found is mapped by software, taking measurements of facial features, such as the distance between the eyes and the length of the jawline, to create a unique set of biometric data. This dataset is then compared to the watchlist. If the image is sufficiently similar to someone in its database, an alert is generated and sent to an engagement team, who will then speak to the person of interest.

4. The laws surrounding LFR

It is lawful for police to overtly deploy LFR, as confirmed by the Court of Appeal. Policing has also commissioned independent testing of the algorithm used with LFR by the National Physical Laboratory. The results of this equitability testing support that at the settings used operationally in policing, the technology does not discriminate on the grounds of gender, age or race.

5. Who uses LFR

Currently only the Metropolitan Police Service (MPS) and South Wales Police have a permanent LFR capability. In 2023, LFR took place at Silverstone at the Formula 1 British Grand Prix and in Essex requested by Essex Police through mutual aid. Notable arrests have been linked to the technology. 

Recently a suspect was arrested in the MPS area after being wanted since 2015 for grievous bodily harm. They were identified via LFR and, despite presenting officers with false identification documentation, they were arrested after further checks. It’s unlikely the suspect would have been identified by traditional policing methods.

• This article was peer reviewed by Ruth Phillips, Senior Technologist, Metropolitan Police Service