The arrest, by Merseyside Police, was hailed as a landmark success in policing history in a statement released to the media last week.
But it emerged that by using its newly-acquired Unmanned Aerial Vehicle (UAV), the force may have committed a criminal offence since it did not have permission from the Civil Aviation Authority (CAA) to fly the device.
Officers used the UAV, which is equipped with thermal imaging cameras, to pursue two suspects travelling in a stolen Renault Clio in Bootle on 26 January.
One 20-year-old was arrested at the scene, and a 16-year-old who ran away and hid in bushes 100 metres (300ft) away was tracked down by the UAV.
Merseyside Police appears to have overlooked new legislation was brought in on 1 January 2010 amid concerns about the safety implications of flying unmanned aircraft in built-up areas.