A Cardiff man is threatening to take South Wales Police to court over the use of new technology to catch criminals in what could become a landmark legal battle.
Since June 2017, the force has been deploying Automated Facial Recognition (AFR) cameras in large crowds.
Specialist vans scan faces seeking a match against a database of persons of interest.
The force says over two thousand positive matches have been made with over 450 arrests, but critics say the technology is a breach of privacy.
Now Ed Bridges says he will take legal action against the force if it doesn't immediately end AFR use.
Mr Bridges who is being represented by human rights organisation Liberty believes his face was scanned as he was Christmas shopping and protesting at an arms fair.
While all faces are scanned, matches with the databased are approved manually by an officer.
Correct match is called a 'True Positive Alert', and an incorrect one a 'False Positive Alert'.
The forces' own figures show there have been thousands of false matches including 2,297 at the Champions league final and 42 at the Wales vs Australia game.
Police insist nobody has been arrested based on a false match.
In a statement South Wales Police say they have received "correspondence relating to the deployment of automated facial recognition technology which we will be responding to in due course.
The force has been very cognisant of concerns surrounding privacy and are confident that our approach is lawful and proportionate."