So, as it turns out, Earth hasn't belonged to humans alone for a very long time. In fact the planet has been open to immigration from a number of other species for years now, provided they use disguise technology so as not to give themselves away. Of course, something like this doesn't stay under wraps forever, and just recently, it finally came out, thanks to an anonymous whistleblower. Humanity reacted as one would expect, with anger and fear. As is the policy with situations like this, a full announcement was made explaining things, but that wasn;t good enough for the frightened humans. Many anti-alien groups began to form, and it wasn;t long before lynch mobs went after any suspected "xenos", killing humans and offworlder's alike.
Finally, a bill was passed that made it illegal for aliens to use camouflage technology. The stated purpose was to prevent any more violence, but in reality it was clearly a means of making sure that those against the aliens could know exactly