Importance of possession
Possession is one of the most important concepts in property law. There are three related and overlapping but not identical legal concepts: possession, right of possession and ownership.
In common law countries, possession is itself a property right. The owner of a property has the right of possession and may assign that right wholly or partially to another who may then also assign the right of possession to a third party. For example, an owner of residential property may assign the right of possession to a property manager under a property management contract, who may then assign the right of possession to a tenant under a rental agreement. There is a rebuttable presumption that the possessor of property also has the right of possession, and evidence to the contrary may be offered to establish who has the legal right of possession to determine who should have actual possession, which may include evidence of ownership (without assignment of the right of possession) or evidence of a superior right of possession without ownership. Possession of a thing for long enough can become ownership by termination of the previous owner's right of possession and ownership rights. In the same way, the passage of time can bring to an end the owner's right to recover exclusive possession of a property without losing the ownership of it, as when an adverse easement for use is granted by a court.
In civil law countries, possession is not a right but a (legal) fact, which enjoys certain protection by the law. It can provide evidence of ownership but does not in itself satisfy the burden of proof. For example, ownership of a house is never proven by mere possession of a house. Possession is a factual state of exercising control over an object, whether the object is owned or not. Only a legal (possessor has legal ground), bona fide (possessor does not know lack of right to possess) and regular possession (not acquired through force or by deceit) can become ownership over passage of time. A possessor enjoys certain judicial protection against third parties even if he is not the owner.
There may be varying degrees of rights to possession. For example, if you leave a book that belongs to you at a cafe and the waiter picks it up, you have lost possession. When you return to recover the book, even though the waiter has possession, you have a better right to possession and the book should be returned. This example demonstrates the distinction between ownership and possession: throughout the process you have not lost ownership of the book although you have lost possession at some point; or instead, the book may have been owned by a third party (such as a lending library) throughout, despite the changes in possession.
