Acquiescence essentially entails your “passive consent” to allow another user to use your registered trademark despite being aware of such use by the other user. Thus, if such a use of your registered trademark is not challenged by you within a statutory period of five years, then you effectively forfeit your right to sue the other user for infringing your registered trademark. Section 33 of the Trade Marks Act, 1999 grants the other user the defense acquiescence against trademark infringement provided, he has adopted and used the said trademark in good faith.
Good faith in this regard implies ignorance or lack of knowledge on the part of the other user about the existence of the infringed trademark. If the owner of a registered trademark despite being aware of the existence of an infringing mark fails to take any action against this other user for a period of five years and instead allows him to invest in publicizing and expanding his business, in such a case, the owner of the registered trademark will not be able to pursue the remedy of injunction against the said other user which he otherwise might be entitled to.
However, there exists an exception to this rule, in case the registered trademark owner is able to prove mala fide intention on the part of the other user i.e. if the other user was fully aware of the existence of the registered trademark and dishonestly adopted the same. Further, mere delay on the part of the trademark owner to take action does not imply acquiescence. The said trademark owner must also have encouraged the other user to use the impugned mark.
The burden of proof in such situations falls on the person claiming the defense. They must prove that they adopted the mark in good faith, that the trademark owner was aware of the infringing activity, that the trademark owner encouraged the use of the said mark and that they had acted on the encouragement of the trademark owner.