adverse possession

Adverse possession in common law, and the related civil law concept of usucaption (also acquisitive prescription or prescriptive acquisition), are legal mechanisms under which a person who does not have legal title to a piece of property, usually real property, may acquire legal ownership based on continuous possession or occupation without the permission (licence) of its legal owner.
It is sometimes colloquially described as squatter's rights, a term associated with occupation without legal title during the westward expansion in North America, as occupying real property without permission is central to adverse possession. Some jurisdictions regulate squatting separately from adverse possession.

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