IP Court judges are required to review defendants' defences to patent infringement lawsuits, including counter-claims for patent invalidity. The IP Court, therefore, provides a second track for an accused infringer to challenge the validity of the patent, in addition to the invalidation track offered by the Taiwan Intellectual Property Office (TIPO), making it no longer an option for a judge to stay a lawsuit pending the outcome of a parallel invalidation action. Although a judge's decision on a patent validity issue is binding to the parties of the lawsuit only, it is rare that a patentee will prevail in a patent infringement suit if the patent has been declared unpatentable by the IP Court in a previous proceeding.