Pre-Occupied

If you have an older sibling, you've heard this: "Possession is nine tenths of the law." This can be applied to just about any situation that involves material, from GI Joes to Hostess Ding Dongs. I have experienced this from both the small and the large, the have and the have not, and I can say that it is frustratingly true. If you are bigger, you have more stuff. And if you are bigger and you don't have more stuff, you try and take it.
This concept dates back to Scotland, where their brogue may be affecting their math, but they insisted that "Possession is eleven points in the law, and they say there are but twelve." I never studied law, but I'm starting to get the impression that if I were to study for the bar, I would start with a volume on possession. In the Hatfield-McCoy feud, with testimony evenly divided, the doctrine that possession is nine-tenths of the law caused Floyd Hatfield to retain possession of the pigs that the McCoys claimed were their property. The Hostess snack cake feud at my house lasted only a few minutes, but most of the same principles applied.
And so I am left to wonder: What is that other tenth of the law? Should I even bother to look it up, since ninety percent of everything else is tipped in possession's favor? Maybe I should content myself with the possessions that I have already acquired. All that stuff has to count for some sort of legal clout, and when I consider the rights of property owners and the way that banks can come in and take away houses full of those possessions it does make me curious about how one percent can control so much. What is ninety-nine percent of the law?