According to Section 21(1) of the Act, Notice of Opposition can be filed by

Section 21(1) of the Trade Marks Act, 1999 allows "any person" to give notice of opposition to a registration within four months from the date of advertisement or re-advertisement. The opponent need not be a registered proprietor, an earlier proprietor or a person aggrieved; "person aggrieved" is the test for removal and rectification under sections 47 and 57, not for opposition.