etymology - Where does the phrase "possession is ( nine points | nine-tenths ) of the law" come from?

I've seen dozens of arguments for the correctness and/or precedence of one version over the other, but have not come across compelling sources or well-documented explanations for either.

Does anyone have solid information on which came first, and how it was derived?

Answer

According to Wikipedia, both English versions derive from a Scottish expression "possession is eleven points in the law, and they say there are but twelve". Wikipedia itself doesn't have a source or etymology for that expression, but I found it in a play by Colley Cibber, "Woman's Wit", from the late 1600s, so it's at least that old.

The term's basic meaning is simply that the overwhelming majority of statutes in the law are based on, or define and regulate, possession of things of value, such as goods, services rendered, money and land. So, at its core it's simply a statement of a known truth.

However, the term as commonly used is a synonym for "finder's keepers", thus referring to a key point involving possession. The fact that a person is in possession of some item of value is usually prima facie that that person is the legal owner of said item, and absent any evidence of a superior claim to the item, or that the person in possession acquired it illegally, that decision will stand. In terms of things which are not legal to possess, the possession is prima facie that the owner is guilty of the crime, and will be found so if there is no compelling evidence to refute it.

The term is also often used to describe "adverse possession of real property". Simply stated, a person who finds apparently abandoned or unimproved land, improves said property and occupies it for a time without hindrance, is considered the "adverse owner" of that property and is entitled to it, despite there possibly being an "actual owner" who holds a title to the land. Adverse possession is also the legal concept behind liens; a person who has improved some property knowingly belonging to another has a claim on a portion of the property equal to the value of improvements rendered, until settled by some other means. There are similar statutes for material goods; if you find money or something else of value, and nobody else offers a valid claim to it given reasonable opportunity, it's yours.