A motorist stopped a 14-year-old cyclist and fined him for riding without lights and a helmet.
Police are trying to trace the driver who flagged the boy down on Dark Lane in Broseley, Shropshire, at about 2030 BST last Friday.
The man said he was fining the teenager £5, which the boy handed over and the motorist drove off towards Ironbridge.
West Mercia Police say the incident is being treated very seriously as the boy should not have been stopped at all.
Pc Mike Belshaw said: "You shouldn't be stopping a 14-year-old boy on a dark night.
"Whatever you may feel, whether the boy was driving without his lights on or whatever, you should be speaking to us or talk to the lad's parents.
"You should certainly not be stopping a 14-year-old boy in this way."