If a mark is unregistered, the owner has to look to the common law for protection and must rely on a passing off action to prevent infringement of his mark.

Passing off actions are notoriously time-consuming and expensive. To succeed in such an action, the proprietor must produce evidence of his ownership of goodwill or reputation in the mark, and evidence that the unauthorised use of his mark amounts to a misrepresentation which is causing, or is likely to cause, damage.