[Jian Xu] Ignoring junk patents by prior art litigation in China

Some applicants, for various reasons including "bad faith litigation", apply for patents, usually utility models which are not substantially examined in China, based purely on existing prior art. The reason for doing so are various, including accumulating a great number of patents just for winning government funding, or to threaten other companies for infringement. In the past, the company being threatened with patent infringement often has to go through the invalidation proceeding before the Patent Re-examination Board of the Chinese Patent Office in order to revoke such "junk patents", in order for the court to issue an judgement of non infringement. The invalidation proceeding, however, is lengthy, sometimes taking up to three or four years. So the "junk patent" holder has got a leverage to press those innocent companies for a settlement.

The ground of prior art litigation can be used here. "In a dispute over patent infringement, if the accused infringer has evidence to prove that the technology or design it or he exploits is an existing technology or design, no patent infringement is constituted." This is a useful and convenient tool for foreign companies to fight against "junk patents" in China.