I hope common-law marriage does not exist in the Federation because bureaucratic procedures for marriage are sufficiently friendly to any civilian for consenting adults of basic intelligence to just get it done.
Y'know, I hear that until just a few years ago, England mandated the assignment of blame for a no-fault divorce to quickly happen, partly due to the corrupt cultural belief that placing such legal roadblocks could dissuade would-be divorcées from going through with their intent in the first place. Concordantly, many clearly out-of-love spouses were forced to cough up the funding to move away for mandatory living apart, and as such, a malicious spouse could torment their would-be-ex-spouse with unnecessarily long legal waits.
It may be beyond the scope of this thread, but I certainly hope by the Federation age, Earth has done away with any legal culture of officials using leeway to interpret in corruptly outdated fashion. I am also a fan of how the Supreme Court of the Republic of India has a procedure where they will not overturn a case if a law is clearly unsuitable, but they will officially request the Parliament of India to pass new legislation to fix the existing problem and prevent recurrences.
Distant acquaintances IRL, scum really, the mother was okay, but the children, adult children, were criminals, lived together in a council house. Local government owns a string of housing units, cheep rent, for poor people, old people or sick people. True story. Only the mother had her name on the lease, but they lived in the same council house for 30 years, until the mother died and the kids were tossed out on the street. Lots of crying and screaming and running in circles with comments like "I was born on that kitchen table!" when all that had to have happened pre-mortem was that the mother had to have put one or both of her children on the lease, which didn't even require a lawyer, just an afternoon of waiting in lines at city hall, and the children, and their children could have lived happily ever after in their ancestral tenement.
An illusion of ownership is certainly possible, if your paperwork is in order.
The Picard's lost that land in world war 2 and didn't get it back until after world war 3, as well as after all the lawyers had been murdered. Their title to that plot is dubious.
Also more recently the land was abandoned for almost 20 years, depending on what Marie Picard had going on... Who is half the age of Jean-Luc, and may not have wanted to live in the shadow of the death of her two favorite men, or Jean-Luc may have just thrown her off the property by her hair, as soon as he got tired of playing with space ships.
...
By the large, humans in the 24th century are vegetarians.
How does a seafood restaurant stay in the black, when %99.999 of the local customer base becomes violently ill after just a nip of clam chowder?