[co-author: Sai Chen]

If you believe that someone is infringing on your patent right in China, you may be angry and unable to refrain from sending him a warning letter(C&D letter) demanding him to stop the infringement.

Sending a warning letter is indeed an option to stop infringement. However, you should be well prepared before sending the warning letter or you might get unfavorable results due to haste.

To avoid legal risks, it is advisable that the following preparations be done before sending a warning letter.

1. To confirm whether there is a high likelihood of infringement

Although a warning letter does not require the same level of evidence as a lawsuit, we should be cautious about asserting infringement. If the right owner is unsure whether the suspected product falls in the protection scope of patent, sending a warning letter alleging infringement just because the suspected infringing product constitutes competitive product may not be considered as a legitimate enforcement of rights but an abuse of rights, which will constitute unfair competition.

In particular, if the warning letters are sent to the product distributors or customers, the obligation of prudent attention will be higher than if they are sent to the manufacturer. Not only shall the right owner make analysis and have reasonable confidence in the infringement before sending the warning, but also shall fully disclose the facts, evidence and relevant information of claiming the infringement in the warning letter.

Therefore, without detailed infringement analysis and proof of a high possibility of infringement, there will be a considerable legal risk for sending the warning letter.

In order to confirm the infringement, it is recommended to purchase the real object of the suspected infringing product and conduct analysis, comparing it with the patent claims in detail. Of course, if in the case that only the design patent is involved, or the patent structure is relatively simple and clear, it is also acceptable to confirm the infringement based on the pictures and description of the publicity materials of the suspected infringing products.

2. It is advised to preserve the necessary evidence of infringement before sending a warning.

As you know, the warning letter is not obligatory. In practice, in almost half of the cases, the warning letter is ignored and cannot achieve the purpose of ceasing infringement. In this instance, it is necessary to take stronger measures, such as requesting administrative action before an administrative office or filing a lawsuit before court, to solve infringement disputes. And evidence is critical for initiating these stronger actions.

Moreover, after receiving the warning letter, if the recipient believes that he does not constitute infringement, he may request the sender to withdraw the warning letter or urge the sender to file a lawsuit. If the sender neither files a lawsuit nor withdraws the warning letter, the recipient has the right to file a lawsuit to confirm non infringement. In such non-infringement litigation, the sender also has the obligation to prove the alleged infringement.

Therefore, to avoid the accused party being more alert and making it more difficult to gather the evidence, it is generally recommended to preserve the necessary evidence of infringement before sending a warning letter.

To purchase the suspected infringing product under the witness of a Chinese notary is the most common and effective way to preserve the evidence. In most cases, one product purchased under a notary should be sufficient, and the notary will seal it after attorney disassembling it and taking pictures on it. If further analysis and identification are needed, more products need to be purchased and sealed respectively.

Other evidence preservation methods include notarizing or time stamping the web pages displaying or selling the infringing goods, notarizing the behavior of suspected infringers when participating in the exhibition and displaying suspected infringing goods, etc.

As the location of infringing actions is closely tied to the jurisdiction, from the perspective of forum shopping, you may choose the desired location to conduct notarized purchase or notarization in exhibition if there are several options.

Additionally, if the budget allows, it is prudent to perform an in-depth investigation of the suspected infringer's production, sales, future trends, and intellectual property rights in advance.

Of course, many right owners choose to send warning letters because it is a quick and low-cost means. For some cases which are not planned to move to the lawsuit, the right owner may not want to spend too much time and cost on the preservation of evidence. Considering this, it is also advisable that the first step, i.e., the confirmation of infringement, should be conducted well, so as to prevent the legal risk of being regarded as abuse of rights and bearing responsibility