Why do companies or individuals sometimes request patents to be invalid?

Legal Countermeasures to Eliminate the Negative Effects of Patent Invalidation on Infringement Litigation Based on the above problems, the Supreme People's Court 1992 "Answers to Several Issues in the Trial of Patent Disputes" (hereinafter referred to as "Answers") stipulates that after accepting the infringement case of utility model patent or design patent, the people's court shall inform the defendant that if the patent is to be declared invalid, it must submit it to the Patent Reexamination Board during the defense period; If the defendant requests to declare the patent right invalid during the defense period, the people's court shall suspend the lawsuit; If the defendant did not make a request for invalidation of the patent right during the defense period, but made a request for invalidation in the subsequent trial, the people's court may not suspend the trial. The defendant requests to declare the patent right invalid during the period of defense in a case of invention patent infringement accepted by the people's court or a case of utility model infringement confirmed by the Patent Reexamination Board.