The High Court is to deliver a landmark ruling on the use of facial recognition technology by police.
Ed Bridges, 36, from Cardiff, says the use of the technology by South Wales Police caused him "distress" and violated his privacy and data protection rights by processing an image taken of him in public.
He crowdfunded his action against the force after claiming his face was scanned while doing Christmas shopping in 2017 and at a peaceful anti-arms protest in 2018.
Mr Bridges' case, supported by human rights campaign group Liberty, is the first legal challenge in the UK against the use of automatic facial recognition (AFR).
Facial recognition technology maps faces in a crowd by measuring the distance between features then compares results with a "watch list" of images - which can include suspects, missing people and persons of interest.
South Wales Police has been using the technology since 2017 and is considered the national lead force on its use.
The force argued the use of AFR does not infringe the privacy or data protection rights of Mr Bridges as it is used in the same way as photographing a person's activities in public.
It said it does not retain the data of those not on its watch list, although it does keep CCTV images from the scanning process for up to 31 days.
Two senior judges will give their decision at the High Court in London today.