The Contract of Sangrae La was written by High Chancellor Ramulein. It decrees that from that point that Empirian contact and 'meddling' on Earth is punishable by death/imprisonment/torture.
It is constantly flaunted.
Breaking the Contract of Sangrae La, with the Distortion Field now in effect, does not carry much of a sentence. In the time of only the cloak of Gorok's shields and Empirian vigilance, trespassing was usually met with execution, but that era was short-lived as the Distortion Field removed the need for such action. There are some Empirian officials that still enjoy imprisoning or slaying law-breakers, but the point of enforcement is now mainly to prevent Human contact rather than to punish Empirians who go to Earth.