Police explain speed camera 'tactics' after video of officer shared online Merseyside Police responded to questions over mobile speed cameras and whether officers need to be visible Updated Police officer operating mobile speed camera Police have confirmed they don’t have to be visible when operating mobile speed cameras after being challenged in a video on Twitter. The footage shows an officer standing against a bus stop monitoring the speed of oncoming traffic. Sharing the video to Twitter, the person filming claimed the officer was “blending in" and drivers couldn't see him from a distance. The video was shared with the caption: “@MerseyPolice are these tactics legal??”