When the question is as to the gain of two persons, the cause or title of the party in possession is the better one.

Explanation

(English-origin maxim.) Where two parties each claim gain from a disputed thing, the party already in possession holds the stronger position and need not yield absent proof of superior title.

Where this applies

• Two cousins both claim they should get grandma's antique piano, but the one who has had it in her living room for the last ten years has the stronger position.
• A buyer and seller dispute who owns a piece of equipment after a deal falls through, and the seller still has it sitting in his warehouse.
• Two neighbors both claim ownership of a strip of land between their lots, but the one who has been mowing it and maintaining it for years holds the advantage.