THE ENCYCLOPEDIA GALACTICA
The human institution of marriage has had a somewhat checkered history.
In ancient times legal marriage was mainly confined to the aristocracy where matters of inheritance and the transfer of wealth, property and titles made it important for there to be a written record. The peasantry tended to be less formal, and in any case, give the depredations of their feudal lords, had little money to spare for such luxuries as marriage.
By the Atomic era, marriage had become a nearly universal institution on Earth, although the extent of its practice varied with geographic regions.
The activities of The Tyrant (Emperor Ming) during his reign, however, brought the institution of marriage into such disrepute that it almost died out. Ming was married no less than 144 times, each time swearing vows that it was for life. Once he tired of the current spouse an offer was made - a trip to the dreaded Tower of London, or a pension and a one-way ticket to a distant star system.
Needless to say virtually all of them took the one-way ticket, which enabled Ming to divorce them on the grounds of desertion, and re-marry. The 144th marriage resulted in a whole school of underground humour based around the word 'gross'.
During the Interregnum it became obvious that, at least among the propertied classes, there was a need for some legal form of marriage. The worker classes, to the contrary, avoided it like a plague. This was because the law provided that not only could assets by passed on to heirs, but that legal heirs were also responsible for outstanding debts.
There was considerable debate about the form that marriage should take, and not a little bloodshed, since it was an issue that raised great passions. Eventually, it was decided that the Galactic Administration would provide a means of registering legal marriages. The ceremony is secular, and the Galactic Administration makes no rules concerning the sex or species of the partners*. It will only marry couples, on the grounds that there are outsystem authorities that provide for marriages of more than two partners.
If is left to the religious authorities to perform what is usually known as the 'solemnisation' of the marriage. Normally a couple wishing to marry will go through the civil, Galactic Administration ceremony and then go on to a religious ceremony. The religious ceremony is not compulsory, and many who have no religion, or whose religion is not theist, just go through the secular ceremony.
Although the civil ceremony is open to all, the religious authorities will only solemnise couple who meet the specific requirements of their religion. It is normal for the authorities, for a suitable fee, to make available a suitably decorated room for the religious ceremony.
Currently, weddings can be registered at the Main Registry Office on Earth.
*There is one exception to this rule. The Galactic Administration will not marry a couple if one of the putative partners is a member of a species that eats its mate after consummation of the marriage.