The law of passing off is a common law remedy to enforce unregistered trademark rights. It is based on the principle that no man is entitled to steal another’s trade by deceit. The law of passing off prevents misrepresentation of one’s goods or services as being the goods and services of another. Unlike the statutory remedies which require a trademark to be registered, passing off can be sought for unregistered marks. The remedy of passing off allows holders of unregistered trademarks to stop or prevent others from copying the mark, packaging, or the get-up.
The modern law of passing off was laid down in the case of Reckitt & Coleman Products Limited v Borden Inc., 1991  WLT 491, otherwise known as the "Jiff Lemon Case". This case involved the well-known lemon-shaped container of Reckitt which was misrepresented by Borden. The use of a similar-looking container by Borden was held to infringe Reckitt's rights. This case also laid down the “Classic trinity test” for passing off. According to this test, a person claiming an action for passing off needs to establish the following three elements:
Goodwill or reputation: The claimant must establish that his goods and services have acquired goodwill or reputation in the marketplace by association with a particular get-up distinguishable from its competitors.
Misrepresentation: Additionally, the claimant has to demonstrate that the other person misrepresented the goods and services which likely led the public to believe that the goods and services offered were those of the claimant.
Damages: Further, the claimant must establish that damage has or will be caused.
The legal remedy of passing off offers wider protection for trademarks than the statutory remedy as it protects the goodwill of a business in a wide range of situations. But seeking remedies under both statutory law and the common law of passing off is advantageous to the claimant as there have been instances where statutory claims have failed but passing off claims have proven to be successful.