One Voice Laws:
Shortly after the Union Charter was ratified, the Executive Council passed a law that established a single common language for the Union population. Ostensibly this was done because standardization of language allowed for much safer working conditions in space. However, the idea of homogenizing the culture of the Union, through the establishment of an official language, was widely thought to be the primary reason for the decision. This law was initially met with resistance, but over several decades it was eventually accepted.
The language chosen in the original ordinance was based on the most common form of English used by the people who were alive in 2101. It is closely tied to the North American variant of English and incorporates occasional words lifted from other former Earth cultures.
Some colonies still maintain widespread traditional language usage with most notably, Tokyo Down Under and Lunagrad still using traditional languages in anything that is not official communication.
Slango evolved as a dialectic variant of English shortly after the space elevators began bringing larger numbers of immigrants up from the surface of the Earth. It was a shorthand form of speaking that could be quickly picked up by the children of refugees and so it includes a wide range of slang and simplified grammatical structures.
Slango worked as a shorthand that bridged the gap between traditional languages and the mandatory official speech of the Union. As the children of the first waves of settlers grew up, the language rooted in and became widespread in spite of the need to maintain more formal communication styles for official interactions. Common usage forms of Slango have infiltrated the formal language and often they will slip into even the highest levels of communication.
The interactions of unaligned business people are often exclusively conducted in Slango, and it is considered the language of negotiation on the concourse level of society.