An opposition proceeding is an administrative process available under the patent and trademark law of many jurisdictions which allows third parties to formally challenge the validity of a pending patent application ("pre-grant opposition"), of a granted patent ("post-grant opposition"), or of a trademark.
[3] A statement of opposition can only be filed during the two-month period after a trademark application is approved by the Canadian Intellectual Property Office (CIPO) and advertised in the Trademarks Journal.
[4] The trademark applicant and opponent then submit pleadings, evidence and arguments to the Trademarks Opposition Board (an administrative body within CIPO), which hears and makes decisions in opposition proceedings.
[3][4][5] The Board can either refuse the trademark application (in whole or in part) or reject the opposition.
[4] This decision can be appealed to the Federal Court of Canada by both the trademark applicant and opponent.