According to Article 18 of "Interpretation of the Supreme People's Court on Issues Concerning the Application of Law in the Trial of Disputes over Infringement of Patent Rights," effective as of 1 January 2010, where a patentee sends a warning to others for infringing a patent and where the patentee neither withdraws the warning nor files a lawsuit within one month upon receiving a written reminder in which the person warned or the interested party urges the patentee to exercise his/her patent right, or within two months upon issuing the written reminder, the courts shall accept the case if the person warned or the interested party files a suit for a declaratory judgment for non-infringement. The issue of whether the patentee's act of sending a warning letter to others may constitute a tort should be determined on a case-by-case basis according to "Anti-Unfair Competition Law of the People's Republic of China" and "Tort Law of the People's Republic of China".
In the case of Beijing People's Higher Court Jing-Min-Zhong Case No. 6 Judgement, the defendant sent warning letters to the plaintiff and its clients and asserted the manufactures of the products by the plaintiff and the sale of these products by its clients infringe the dependent's Patent No. ZL201010127999.8 on 11 September 2015. The warning letter was solely based on plaintiff's product photos, not detailed patent infringement analysis. On 13 October 2015, the plaintiff in reply expressed no infringement and asserted that the acts of the defendant had damaged its reputation among its clients. The plaintiff requested the defendant to withdraw the warning letter or file a lawsuit with a court to resolve the dispute, but the defendant did not follow the plaintiff's request. Thereafter, the plaintiff filed a suit for a declaratory judgment for patent non-infringement with the Beijing IP Court and requested the defendant eliminate the effects created by the defendant's improper acts of sending these warning letters.
The Beijing IP Court, in the first instance, ruled: 1. that it is confirmed the plaintiff's products do not infringe on the patent concerned; and 2. the defendant should publish a statement on its website that the plaintiff's products do not infringe on the patent concerned for fifteen consecutive days to eliminate the effects created by the defendant's improper acts of sending these warning letters. The Beijing People's Higher Court, in the second instance, sustained the judgment of the first instance.