Nemo dat quod non habet

Nemo dat quod non habet, literally meaning "no one gives what he doesn't have" is a legal rule, sometimes called the nemo dat rule, that states that the purchase of a possession from someone who has no ownership right to it also denies the purchaser any ownership title. It is equivalent to the civil (continental) "Nemo plus iuris ad alium transferre potest quam ipse habet" rule, which means "one cannot transfer more rights than he has". The rule usually stays valid even if the purchaser does not know that the seller has no right to claim ownership of the object of the transaction (a bona fide purchaser); however, in many cases, more than one innocent party is involved, making judgment difficult for courts and leading to numerous exceptions to the general rule that aim to give a degree of protection to bona fide purchasers and original owners. The possession of the good of title will be with the original owner.

In American law, a bona fide purchaser who unknowingly purchases and subsequently sells stolen goods will, at common law, be held liable in trover for the full market value of those goods as of the date of conversion. Since the true owner retains legal title, the seller is liable even in a chain of successive bona fide purchasers (i.e., the true owner can successfully sue the fifth bona fide purchaser in trover). However, the problem of successive bona fide purchasers can be remedied: If the jurisdiction recognises an implied warranty that the seller has title to the property (Article 2 of the Uniform Commercial Code (UCC) in the United States), then the bona fide purchaser can sue the seller for breach of that implied warranty. Courts of equity traditionally also recognise various other exceptions, likely giving rise to the idea embodied in the modern UCC.

This rule is exemplified in circumstances like the Holocaust reconciliation movement, where property, such as works of art, stolen or confiscated by the Nazis was returned to the families of the original owners. Anyone who purchased the art or thought they had ownership was denied any rights over the litigious property due to the nemo dat rule.

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