The Spacecops began as an elite secret police force operating under the reign of the Tron legions. They were tasked with hunting down and eliminating the enemies of the various emperors, any non-yellow minifig, and anyone who thought that wearing black all the time was too somber. As a result of Imperial paranoia, the Spacecops were often used to find and destroy any relatives or potential heirs to the Empire, often extinguishing whole bloodlines on the whim of the Emperor. After the Darktron Empire crumbled due to a lack of minifigs willing to claim Imperial lineage, the Spacecops all but disappeared, fading into obscurity and squabbling amongst themselves over who to serve, and what their new uniforms should look like. The organization was embroiled in a bloody and drawn-out civil war, with many minifigs killed, maimed or otherwise inconvenienced. Just when it seemed that it would never end, it didn't.
The end of the war came During the Gray Shift, when they were finally able to decide on a new uniform. It was gray, because gray was totally in right now.
The Spacecops, armed with their new stylish duds, now wage a xenocidal campaign against any non-standard minifig, such as Squidheads, Peaches, and any minifig without a Spacecop-certified™ face/facial expression. Spacecops are diametric enemies of space pirates, anything space pirate related, and the Space Mafia. They basically function as the brikverse's international police force. They coordinate local and national police departments and chase criminals across Nehellium like the real life Interpol or EVE Online's CONCORD, but regularly ignoring petty things like national sovereignty and minifig rights FOR GREAT JUSTICE.
The Spacecop Headquarters is Spacecatraz.