Passing off is a common law tort which can be used to enforce unregistered trademark rights. Passing off essentially occurs where the reputation of party A is misappropriated by party B, such that party B misrepresents this reputation and damages the goodwill of party A.
The law of passing off prevents one person from misrepresenting his or her goods or services as being the goods and services of the plaintiff, and also prevents one person from holding out his or her goods or services as having some association or connection with the plaintiff when this is not true.
A cause of action for passing off is a form of intellectual property enforcement against the unauthorised use of a mark which is considered to be similar to another party's registered or unregistered trademarks, particularly where an action for trademark infringement based on a registered trade mark is unlikely to be successful (due to the differences between the registered trademark and the unregistered mark). Passing off has developed from the common law, whereas statutory law such as the United Kingdom Trade Marks Act 1994 provides for enforcement of registered trademarks through infringement proceedings.
Passing off and the law of registered trademarks deal with overlapping factual situations, but deal with them in different ways. Passing off does not confer monopoly rights to any names, marks, get-up or other indicia. It does not recognize them as property in its own right.
Instead, the law of passing off is designed to prevent misrepresentation to the public where there is some sort of association between the plaintiff and the defendant. Where the defendant does something so that the public is misled into thinking the activity is associated with the plaintiff, and as a result the plaintiff suffers some damage, under the law of passing off it may be possible for the plaintiff to initiate action against the defendant.