(3) The decision of the Registrar shall be subject to appeal to the Crown Attorney who shall, if required, hear the applicant and the opponent, if the opponent is, in his or her opinion, a person entitled to be heard in opposition to the grant of the patent, and shall decide the case; and the Crown Attorney may if he or she thinks fit, obtain the assistance of an expert, who shall be paid such remuneration as the Crown Attorney with the consent of the Governor General may determine.