The patent office shall register and announce the decision after it becomes legally effective. An invalid patent right shall be regarded as nonexistent from the beginning. The decision to declare the patent right invalid has no retrospective effect on the infringement treatment that has been executed or the contract that has been performed. However, if the patentee maliciously causes losses to others, it shall make compensation, and obviously unfair shall return part or all of the expenses.
According to Article 45 of the Patent Law
Since the date when the patent administrative department of the State Council announced the grant of the patent right, any unit or individual may request the Patent Reexamination Board to declare the patent right invalid if it considers that the grant of the patent right is not in conformity with the relevant provisions of this Law.
Article 46
The Patent Reexamination Board shall promptly examine the request for invalidation of the patent right and make a decision, and notify the claimant and the patentee. The decision to declare the patent right invalid shall be registered and announced by the patent administration department of the State Council. Anyone who refuses to accept the decision of the Patent Reexamination Board to declare the patent right invalid or maintain the patent right may bring a lawsuit to the people's court within three months from the date of receiving the notice. The people's court shall notify the other party to the procedure for requesting invalidation to participate in the proceedings as a third party.
Article 47 An invalid patent right shall be regarded as nonexistent from the beginning. The decision to declare the patent right invalid has no retrospective effect on the patent infringement judgments and conciliation statements made and executed by the people's court before the patent right was declared invalid, the decisions on handling patent infringement disputes that have been performed or executed, and the patent licensing contracts and patent transfer contracts that have been performed. However, if the patentee's malice causes losses to others, it shall make compensation. If the patent infringement compensation, patent exploitation fee and patent transfer fee are not returned in accordance with the provisions of the preceding paragraph, which obviously violates the principle of fairness, they shall be returned in whole or in part.