Legal basis: Article 45 of the Patent Law of People's Republic of China (PRC). Any unit or individual may request the Patent Reexamination Board to declare this patent invalid as of the date when the patent administrative department of the State Council announced the grant of this patent. This procedure is called "patent invalidation procedure", and the invalidated patent is regarded as nonexistent from the beginning, even if the actor implements the technology without permission, it does not constitute infringement.
"Several Provisions of the Supreme People's Court on the Applicable Law in the Trial of Patent Disputes" Article 11 If the defendant requests to declare the patent right invalid during the period of defense, the people's court shall not suspend the proceedings in a dispute case of infringement of the invention patent right accepted by the people's court or a dispute case of infringement of the utility model or design patent right examined and maintained by the Patent Reexamination Board.