Nemo dat quod non habet

Nemo dat quod non habet, literally meaning "no one [can] give what he does not 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. This 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 it is often difficult for courts to make judgements as in many cases there is more than one innocent party. As a result of this there are numerous exceptions to the general rule which aim to give a degree of protection to bona fide purchasers as well as original owners.