The Earth Union was formed out of the old United Nations in the middle of the 2nd Century PD on the initiative of the Greens and the Neo-Luddites. They soon had laws requiring loyalty oaths passed in most member countries.
The Customs Patrol was charged with patrolling the Sol System, enforcing traffic and trade law, and fighting piracy. Only Earth-born citizens of the Union were allowed into the Officer corps. (HHA6.1: BTB)