According to Jewish law, just because someone has possession of property and lives or works it, he cannot claim ownership of it. A person only becomes an owner if he receives that status from the original owner through a sale or by receiving a present, or if he claims an object that is hefker, performing a formal act of possession (a kinyan). Thus, there can be no claim of ownership based on “squatters’ rights” and if someone else comes with proof of ownership, the person living or working the land will have to prove that he bought it.
The halakha recognizes that a person cannot be expected to retain purchase documents forever, so if the person working the land can show that he has been in possession of the land for an extended period of time, working it with the original owner’s knowledge, that will serve as an acceptable proof of purchase.
Perek Ḥezkat HaBatim, the third chapter in Massekhet Bava Batra, which begins on today’s daf, discusses these proofs – how long a person must have been in possession of the object in order to make his claim of ḥazaka (presumptive ownership), what uses constitute possession, whether it differs when applied to different objects, etc.
The Ritva points out that the term ḥazaka as it is used in this context is qualitatively different than the ḥazaka used as a kinyan – in taking possession of an object. He argues that in our case we are concerned with proof of ownership, while in the case of kinyan we need a formal act that creates the ownership. The Ge’onim see a single meaning for the term ḥazaka – holding or having possession of the object in a way that shows ownership. This ḥazaka is applied differently in these two different cases.