Opposition proceeding

An opposition proceeding is an administrative process available under the patent and trademark law of most jurisdictions which allows third parties to dispute the validity of a granted patent or trademark.
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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, a USPTO administrative tribunal.

Any person who believes that he or she will be damaged by the registration of a mark may file an opposition, but the opposition may only be filed in response to the publication of the mark in the  Official Gazette.

Context: Trademark