Legal basis: Detailed Rules for the Implementation of People's Republic of China (PRC) Patent Law.
Article 67 The Patent Reexamination Board shall send a copy of the request for invalidation of the patent right and relevant documents to the patentee, asking him to state his opinions within a specified time limit. The patentee and the claimant for invalidation shall reply to the notice of transferring documents or the notice of examining the request for invalidation issued by the Patent Reexamination Board within a specified time limit; Failure to reply within the time limit shall not affect the trial of the Patent Reexamination Board.
Article 68 In the process of examining the request for invalidation, the patentee of a patent for invention or utility model may amend his claim, but shall not extend the scope of protection of the original patent. The patentee of a patent for invention or utility model shall not modify the patent specification and drawings, and the patentee of a patent for design shall not modify the pictures, photographs and brief descriptions.
Article 69 The Patent Reexamination Board may, at the request of the parties concerned or the needs of the case, decide to conduct an oral hearing on the request for invalidation. If the Patent Reexamination Board decides to conduct an oral hearing on the request for invalidation, it shall send a notice of oral hearing to the parties concerned, informing them of the date and place of the oral hearing. The parties concerned shall make a reply within the time limit specified in the notice. If the claimant for invalidation fails to reply to the notice of oral hearing issued by the Patent Reexamination Board within the specified time limit and does not participate in the oral hearing, his request for invalidation shall be deemed to be withdrawn; If the patentee does not participate in the oral hearing, he may try it by default.