Opposing proceeding is an administrative process in trademark law that allows third parties to oppose registration of a trademark. It is a proceeding before the Trademark Trial and Appeal Board in which the plaintiff seeks to prevent the issuance of a registration of a mark. An opposition is similar to a proceeding in a federal court, but is held before the Trademark Trial and Appeal Board, which is the U.S. Patent and Trademark Office’s (USPTO) administrative tribunal.
Any person who believes that s/he will suffer damage by the registration of a mark can file an opposition. However, the opposition can only be filed in response to the publication of the mark in the Official Gazette.