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& Technology
in Policing

PUBLISHED: 5 Apr 2023

Operational Testing of Facial Recognition Technology


Why test?

The Metropolitan Police Service (MPS) and South Wales Police (SWP) tested Facial Recognition Technology (FRT) with the National Physical Laboratory (NPL). The NPL is a world-leading centre of excellence that provides cutting-edge measurement in science, engineering and technology. Thanks to previous testing by the National Institute of Standards and Technology (NIST) the MPS and SWP knew that their FRT used a high performing algorithm; the aim of the testing was to develop an in-depth understanding of the performance of the algorithms when it was being used in an operational environments. The three policing use cases were:

  • Live Facial Recognition (LFR)
  • Retrospective Facial Recognition (RFR)
  • Operator Initiated Facial Recognition (OIFR)

The NPL test plan was specifically designed to help identify any impact this technology may have on any protected characteristics, in particular race, age and sex.

What do the test results tell us?

The NPL report gives an impartial, scientifically underpinned and evidence-based analysis of the performance of the facial recognition algorithm currently used by the MPS and SWP.  Its findings revealed:

  • We are now able to better understand the demographic performance of our LFR system & There are settings our algorithm can be operated at where there is no statistical significance between demographic performance;
  • that there was no demographic performance variation for RFR; and
  • that there was no demographic performance variation for OIFR


The results from the tests assist the MPS and SWP with further understanding how to use FRT fairly in order to prevent and detect crime, safeguard national security and keep people safe.

The full results are presented in the NPL’S commissioned report:  Facial Recognition Technology in Law Enforcement Equitability Study